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If you can imagine it, you can create it.

If you can dream it, you can become it.

William Arthur Ward

DEA Modelling of the Marine Environment 01/02

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INDE+

1 INTRODUTION!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! 1

1!1 Tagu" E"tuar#!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! $1!1!1 Mor%holog#!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! $

1!1!2 &h#"i'al and (iologi'al &ro%ertie"!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! )

1!1!$ *i"h in the Tagu" E"tuar#!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! +

1!2 Euro%ean An'hov#, Engrauli" en'ra"i'olu" !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! -

2 MET.ODOO!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

2!1 3tate of the Art !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

2!2 on'e%tual Model !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! 12

2!$ Individual ro4th Model 5IM6 !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! 1$2!$!1 Intera'tion 7et4een fi"h and ha7itat!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! 1+

2!) &o%ulation ro4th Model!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! 1-

2!)!1 Intera'tion 7et4een fi"h %o%ulation and ha7itat !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! 18

2!+ *i"h movement !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! 1

$ MODE IM&EMENTATION !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! 22

$!1 Individual ro4th Model!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! 22

$!2 &o%ulation ro4th Model!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! 2$

) RE3UT3 AND DI3U33ION !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! 2-

)!1 Individual ro4th Model!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! 2-

)!2 &o%ulation ro4th Model!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! $0

)!2!1 ife #'le in the *i"h &o%ulation!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! $0

)!2!2 3'enario" !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! $1

+ ONU3ION3!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! $8

- REOMMENDATION3 *OR *UTURE WOR9!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! )0

: A9NOWEDMENT3 !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! )1

8 RE*ERENE3 !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! )$

A A&&ENDI; !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! )

A!1 MO.ID2000 !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! )

A!1!1 agrangean Tra'er" Module !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! +1

A!1!2 Eulerean Tran"%ort Module!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! +1

A!1!$ ohe"ive 3ediment Tran"%ort Module !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! +2A!1!) Water

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,INTRODU-TION

oa"tal =one" are the mo"t heavil# %o%ulated and e'ologi'all# vulnera7le area" 4orld4ide!

.ere man# different and often 'ontradi'tor# intere"t" e>i"t 4hi'h have to 7e 'arefull#managed! *or thi" %ur%o"e it i" a7"olutel# ne'e""ar# to enhan'e the fore'a"t 'a%a'it#

regarding the medium to long?term evolution of the 'oa"tal marine "#"tem in vie4 of

human a'tivitie" and natural 'hange"!

*ore'a"t model" for 'oa"tal 4ater", 'om%lemented 7# 'ontinuou" monitoring "#"tem" and

"u%%orted 7# effi'ient data7a"e", 'an %rovide thi" @ind of a""i"tan'e, hel%ing in

the develo%ment of management 'on'e%t" 'om%ati7le 4ith "u"taina7le gro4ing and 4ith the

%re"ervation of e'o"#"tem" integrit#! The"e integrated "#"tem", if u"ed in a regular 7a"i" 7#

lo'al authoritie", 'an hel% them to a'hieve im%ortant im%rovement" in 'oa"tal management

%ra'ti'e!

Regarding all the u"e" that an e"tuar# i" "u7mitted to, it i" im%ortant to a""e"" the reuired

environmental ualit# for the maintenan'e of the fi"h "to'@"! It i" im%ortant to @no4 the

lo'ation of the "%e'ifi' 'oa"tal area" 'ho"en 7# the fi"h for their "%a4ning and feeding

a'tivitie", "o that de'i"ion ma@er" ma# have the @no4ledge of the more relevant area" to

%rote't and therefore the mea"ure" needed to 7e im%lemented at an u%%er level!

To 7e a7le to %redi't where is the fish going one ha" to gather 7iologi'al and e'ologi'al

field data and the re"ult" of e>%eriment" that %rovide an e"timate of the fi"h environmental

%referen'e"! O'ean", la@e" and %ond" offer their inha7itant" environment" that are varia7le

in "%a'e and time! Movement" in the"e "#"tem", either verti'all# or hori=ontall#,

im%o"e gradient" in gro4th and "urvival through the effe't" of tem%erature, food'on'entration, "en"or# 'a%a7ilitie", %redator den"it# and dete'tion ri"@! All large and

'ommer'iall# im%ortant marine fi"h "to'@" underta@e "ea"onal hori=ontal migration"! The

e>tent of the"e migration" varie" 4ith age, "i=e and environmental 'ondition"! Under"tanding

the for'e" that 'reate "%atial di"tri7ution" i" a maBor 'hallenge to e'olog#, 7ut al"o ha"

'lear e'onomi' 7enefit" to human", 7# allo4ing more %re'i"e a""e""ment" of managed

"to'@" 5i"@e et al,

186! While field "tudie" ma# reveal %attern" at a given time and %la'e and la7orator#inve"tigation" ma# i"olate effe't" of "ingle 'au"e", model" ma# 'om7ine "everal for'e" in'ontinuou" "%a'e and time!

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An effe'tive management of the fi"herie" re"our'e" reuire" an under"tanding and the

a7ilit# to %redi't long?term flu'tuation" in a7undan'e and 7ioma"" %rodu'tion due either to human

%ertur7ation" or environmental variation"! Therefore it i" reuired a detailed "tud# of the

life "tage "%e'ifi' %ro'e""e" of the fi"h! Re'ent "tud# ha" indi'ated that ver# often it i"

in"uffi'ient to "tud# the averaged earl#?life d#nami'" of a #ear 'la"" to under"tand

re'ruitment %ro'e""e" in fi"h %o%ulation"! To under"tand the"e d#nami'" it ma# 7e ne'e""ar#

to follo4 diar# gro4th and mortalit# for a %eriod of time 5o4an Cr et al, 16!

&ro'e""e" that o%erate during a "%e'ifi' time of the #ear or during a "%e'ifi' life "tage ma# 7e

'riti'al in determining annual re'ruitment level! .o4ever, e>amination" of life "tage "%e'ifi'

%ro'e""e" are diffi'ult to ma@e in the field! 3imulation modelling i" an attra'tive alternative

that %rovide" a 'onte>t for evaluating the effe't" of man# intera'ting fa'tor" %otentiall# im%ortant

affe'ting re'ruitment!

Thi" 4or@ 4a" develo%ed in the "'o%e of the euro%ean DEA 5Diploma Eruditionum

Altarum6 in Modelling of the Marine Environment! The goal of thi" 4or@ i" the

develo%ment of a gro4th model for a fi"h %o%ulation in a 'oa"tal e'o"#"tem! In the near

future, thi" gro4th model 4ill %rovide the 7a"i" to 7uild a model of the movement of fi"h

in the marine environment a''ording to their environmental %referen'e", %ermitting then to

%redi't the fi"h %referred area"! The"e model" 4ill 7e in"erted in the alread# develo%ede'oh#drod#nami' "#"tem, MO.ID2000 5for more information "ee "e'tion A!16!

The Tagu" E"tuar# 5&ortugal6 i" "ele'ted a" the frame4or@ to "tud# the gro4th of the

%o%ulation of euro%ean an'hov#, Engraulis encrasicolus, "in'e there inha7it" a 'on"idera7le

%o%ulation of thi" "%e'ie"!

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,., Ta'u(E(tuar#

,.,.,Morpho*o'#

The Tagu" e"tuar# i" the large"t e"tuar# of &ortugal and one of the large"t euro%ean

e"tuarie"! It i" lo'ated near i"7on 5$8))N, 08W6, 'a%ital of &ortugal and the mo"t

im%ortant 'it# 7uilt on it" margin" 5"ee *ig!16! The metro%olitan area ha" no4ada#" around

2 million inha7itant", an im%ortant har7our and 7ig indu"trial 'om%le>e" around the e"tuar#!

It 'over" an area of a7out $20 @m2, ha" a length of 80 @m from the u%"tream limit of the

d#nami' tidal effe't 5near Muge6 to the river mouth 5near 3! CuliFo da (arra G (ugio6

5*erreira et al, 1)H o"ta, 16! The "u7merged "urfa'e 'hange" from $0000 ha in the

nea% tide to $)000 ha in the "%ring tide 5a7rita Moita, 1+6!

*ig!1 Tagu" E"tuar#!

The e"tuar# i" 'om%o"ed of a dee%, "traight and narro4 inlet 'hannel and a 7road,

"hallo4 inner 7a#! The inlet 'hannel, allo4ing the entran'e of "ea4ater in the e"tuar#, i"

a7out 1+ @m long and 2 @m 4ide 5rea'hing a )0m de%th6, 4hile the 7a# i" a7out 2+ @m

long and 1+ @m

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4ide 54ith a 'om%le> 7ottom to%ogra%h# that in'lude" 'hannel", tidal flat area" and "and

7an@"6! U%"tream, a "ingle narro4 'hannel mar@" the entran'e of the Tagu" river! The

ma>imum de%th i" )2 m near the mouth 54ith an average of 10 m6, 7ut a 'on"idera7le

u%"tream area ha" 2?$ m! It i" a me"otidal e"tuar# 4ith "emi?diurnal tide" 4ith tidal

range" var#ing from 1 to ) m 5o"ta, 16!

The main "our'e of fre"h 4ater of the e"tuar# i" the Tagu" river, 4ith "maller

'ontri7ution" from other river" 5Tran'Fo, 3orraia6! The di"'harge %attern of the Tagu" river refle't"

the regulari=ation 4ith 3%ain, the dr# and 4et "ea"on" and large inter?annual variation"J the

average di"'harge varie" 7et4een 100 and 2200 m$!"?1 5&ina, 2001H o"ta, 1H a7rita

Moita, 1+6! The re"iden'e time of fre"h 4ater i" highl# varia7le and range" from -+

da#" at a di"'harge of 100 m$!"?1 to - da#" at a di"'harge of 2200 m$!"?1H the re"iden'e

time to the modal di"'harge of $00?)00 m$!"?1 i" of a7out 2$ da#" 5Martin" et al, 18)6!

,.,./ Ph#(&!a* a0 1&o*o'&!a*Propert&e(

The e"tuar# i" a mi>ing %la'e of river and o'eani' 4ater"! The "alinit# di"tri7utionde%end" mo"tl# on the river flo4 and on the mi>ing im%o"ed 7# the tidal regime, 4hi'h i"

the main me'hani"m 'ontrolling the di"tri7ution of auati' organi"m" and "u"%ended

%arti'ulate matter in the e"tuar#! There i" a %artial t4o?la#er "tratifi'ationJ "alinit# i" higher

in the dee%er la#er" 7e'au"e the mi>ing of fre"h and "alt4ater i" "lo4 5a7rita Moita, 1+6!

Tem%erature variation" influen'e the e"tuarine 'ommunitie", 7# influen'ing the di""olved

o>#gen and "everal %ollutant" 'on'entration"! In the Tagu" e"tuar#, tem%erature range i"

higher u%"tream, 4ith ma>imum value" at Kila *ran'a de ;ira! There i" a 'on"idera7le

thermi' homogeneit# during 4inter 'om%ared 4ith a %ronoun'ed longitudinal gradient during

"ummer!

The Tagu" e"tuar# i" a highl# %rodu'tive e'o"#"tem, and ha" 'on"idera7le 'on"ervation value,

"in'e it %rovide" an o%timum ha7itat for man# 'ru"ta'ean, mollu"'", fi"h and 7ird "%e'ie"!

Thi" ha" led to the 'reation of a Natural Re"erve in 1:-, 'overing a large "urfa'e of e"tuarine

4ater, mud 7an@", "alt%an", "alt mar"he", i"land" and agri'ultural land 5*erreira et al, 20016!

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The Tagu" e"tuar# %re"ent" a high %rodu'tivit# and the mo"t a7undant %rimar# %rodu'er"

are the "alt mar"h vegetation, mi'ro%h#to7entho", and ma'ro%h#te algaeH together the#

%rovide food for 7enthi' fauna and ha7itat for man# "%e'ie"! The %rimar# %rodu'er" are

re"%on"i7le for the removal of high amount" of nutrient", 4hi'h im%rove" the e"tuarine 4ater ualit#!

Although the e"tuar# i" re'ogni"ed a" a highl# %rodu'tive e'o"#"tem, "ome of it" natural

re"our'e" have 7een degraded in the la"t $0 #ear" due to the in'rea"ed 4ater and "oil

%ollution! Dire'tl# or indire'tl# the e"tuar# i" the final di"%o"al %la'e of the 'at'hment?

%rodu'ed effluent"! The im%lementation of the EU Water Dire'tive" i" %rogre""ivel#

redu'ing the organi' matter and nutrient" load in the e"tuar#! The uantifi'ation of the

ma>imum admi""i7le load" di"'harged from ea'h affluent "u7?7a"in" 5Tagu", Tran'Fo and

3orraia and "maller "tream"6 reuire" a good under"tanding of the 7iologi'al %ro'e""e"in"ide the e"tuar# and in the 'oa"tal =one near the e"tuar#L" mouth, 4hi'h i" an im%ortant

re'reational and lei"ure =one!

All tho"e fa'tor" 'ontri7ute for the need of effi'ient managing tool" that allo4 the lo'al

authoritie" to ma@e de'i"ion" 7a"ed on the 7etter @no4ledge that the# ma# have availa7le

in ea'h moment! To a'hieve thi" @no4ledge it i" ne'e""ar# to 'olle't information a7out the

different %arameter" that %la# an im%ortant role in the e'o"#"tem, integrate thi" information

in order to ma@e it re%re"entative of the 4hole e"tuar# and ma@e it availa7le in a

'om%rehen"ive 4a# to the de'i"ion ma@er"!

,.,.2 F&(h & the Ta'u(E(tuar#

The maintenan'e of the 'oa"tal fi"herie" "to'@" i" to a large e>tent de%endent on the natural'ondition" of the e"tuar#, "in'e "everal fi"h "%e'ie" u"e it a" a nursery area, or migrate

through the e"tuar# at different "tage" in their life '#'le! The nur"er# =one" are lo'ated in

the "hallo4e"t u%"tream %art of the e"tuar#, near Kila *ran'a de ;ira, MontiBo and Al'o'hete!

The e"tuarine 'ommunit# varie" throughout the #ear and i" rare the fi"h that

inha7it %ermanentl# in the e"tuar#! A" the "trong 'urrent" of the e"tuar# 'an drag egg", the

maBorit# "%a4n" in the "ea! Neverthele"" the "%e'ie" 4ho"e life '#'le develo%" in the

e"tuarine environment have to arrange me'hani"m" that hinder thi" drag of egg" 5o"ta, 16!

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In 1- and 1:, o"ta 516 identified )) fi"h "%e'ie" in thi" e"tuar#, in'luding

re"ident "%e'ie", "%e'ie" that u"e the e"tuar# a" a nursery, migrant and o''a"ional "%e'ie"!

3ome of the mo"t a7undant "%e'ie" in thi" e"tuar# i" the euro%ean "ea7a"" 5Dicentrarchus

labrax6, the 'ommon "ole 5Solea vulgaris6, the gilthead "ea7ream 5Sparus aurata6 4ith

'on"idera7le 'ommer'ial intere"t, the "and and mar7led go7# 5Pomatoschistus minutos and P.

microps6 and the euro%ean an'hov# 5Engraulis encrasicolus6, thi" la"t 4ith

'ommer'ial intere"t for fi"herie"!

The an'hov# and the go7# live in thi" e"tuar# throughout their life '#'le, 4hile the

euro%ean "ea7a"", the 'ommon "ole and the gilthead "ea7ream u"e it a" a nursery! The"e

la"t "%e'ie" "%a4n in the "ea and the Buvenile" u"e the e"tuar# a" foreground nursery,

4here the# find greater amount of food, minor num7er of %redator" and good 'ondition" oftem%eratureH the# remain during a varia7le %eriod de%ending on the "%e'ie" and return to the

"ea! 3ome adult" enter o''a"ionall# in the e"tuar# to feed 5o"ta, 1H Monvoi"in, 1:6!

The "urvival of the e"tuarine fi"h i" affe'ted 7# diver"e fa'tor" a" %ollution, overfi"hing

and dam"! The overfi"hing of "everal "%e'ie" in thi" e"tuar# 'au"e" the de'rea"e of the fi"h "to'@"

7e'au"e Buvenile" are 'aught, thu" %reventing the adult %o%ulation to in'rea"e and

'on"euentl# %rodu'ing a minor num7er of egg"!

,./ Europea A!ho"#) E'rau*&(e!ra(&!o*u(

The euro%ean an'hov# Engraulis encrasicolus 5famil# ?

Engraulidae, order G lu%eiforme"6 i" a ver# a7undant

"%e'ie" from Nor4a# to England, all 4e"tern Euro%e,

Mediterranean, (la'@ and A=ov "ea", 3outh Afri'a, ulf

of 3ue=, 4e"tern Indian O'ean, Mauritiu", 3e#'helle" and

u%4elling area around 3omalia, a" "ho4n in *ig!2 5o"ta,

M!C!, 1H Whitehead, 10H Whitehead et al, 1886!

*ig!2 Engraulis encrasicolus di"tri7ution 5*AO in *roe"e &aul#,20006

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It i" a %elagi' and mainl# 'oa"tal marine "%e'ie", forming large "'hool" and feeding on

%lan@toni' organi"m"! It i" a eur#thermi' and eur#haline "%e'ie" that tolerate" "alinitie"

from

+?)1 %%t and in "ome area", enter" e"tuarie", lagoon" and la@e", e"%e'iall# during

"%a4ning a'tivit#! Tend" to move further north and into "urfa'e 4ater" in "ummer,

retreating and de"'ending in 4inter! Thi" "%e'ie" adult mean 4eight i" of $0 g and a

ma>imum length of 20 'm 5"ee *ig!$6!

*ig!$ Euro%ean an'hov#, Engraulis encrasicolus 5*ro"e &aul#, 20006

The euro%ean an'hov# %re"ent" a "hort life "%an 5three to four #ear"6, "ea"onal migration", an

inten"e gro4th and an age of fir"t maturit# 4ith one #ear 5r "ele'tion "trateg#, i!e!

"ele'tion for ma>imum rate of %o%ulation re%rodu'tion in a flu'tuating environment6! It

"%a4n" from A%ril to Novem7er 4ith %ea@" u"uall# in the 4arme"t month"! In the Tagu"

e"tuar# the Euro%ean an'hov# "%a4n" one time in the A%ril/Ma# %eriod 5R, 18-6! Egg"

are elli%"oidal to oval, floating in the u%%er +0 m and hat'hing in 2)?-+ hr", %re"enting a

7ioma"" of 0,22- mg 4et 4eight 5R, 18-6! 3in'e the egg" are %elagi', their "ha%e

%revent" their tran"%ort through the e"tuar#, 7e'au"e it offer" le"" re"i"tan'e to the 'urrent"!

Thi" fi"h "%e'ie" i" a multi%le "%a4ner 5often more than ten 7at'he" 4ithin a "ea"on6!

Thi" me'hani"m i" an effi'ient mean" of en"uring 'om%lete u"e of food and in'rea"e" the

%ro7a7ilit# of %o%ulation "urvival, a" 4ell a" 7eing an ada%tation for un"ta7le environmental

'ondition" and high mortalit# in earl# "tage" of ontogen#!

3urvival of an'hov# larvae i" determined 7# the food availa7ilit# in a %eriod of

omnivorou" feeding, and there i" a 'lo"e "#n'hron# 7et4een @e# larval a7undan'e and the

=oo%lan@ton %o%ulation ma>imum! The an'hov# feed" mainl# on 'o%e%od nau%lii larvae, mollu"'larvae, %h#to%lan@ton, 'o%e%od" and 'irri%ed" 5(erdni@ov et al, 16!

The euro%ean an'hov# i" a highl# 'ommer'ial "%e'ie", mar@eted fre"h, dried, "mo@ed,

'anned, fro=en, made into fi"h meal and u"ed a" 7ait 5*rimodt, 1+6! A" a target fi"herie"

"%e'ie", the an'hov# ha" re'eived inten"ive "tud# 5Win@ler, 2000H (erdni@ov, 3!K! et

al,

1H o"ta, 1H 3anto" et al, 1:H Tudela &alomera, 1:H Magoula" et al, 1-H

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M#er" et al, 1+H 9oranteng, 1$H Morale"?Nin &ertierra, 10H 9ara'am D=gne",

10H &alomera leonart, 18H 3%ana@i" et al, 18H &alomera et al, 188H Er@o#un'u

O=damar, 18H Uriarte Adtudillo, 18:6!

The an'hov# fi"herie" management of the "outh4e"tern Euro%e and of the Mediterranean 3ea

i" diffi'ulted 7# the large interannual varia7ilit# in the %o%ulation" a7undan'e! The an'hov#

life '#'le "eem" to 7e ada%ted to a highl# varia7le environment, %re"enting 7oth high

gro4th rate and fe'undit# and al"o a'tive migration" to area" that gather 7etter 'ondition"

5&alomera et al, 1886!

The model 7uilt in the frame4or@ of thi" the"i" i" a%%lied to thi" fi"h "%e'ie", "in'e 516 it

ha" an im%ortant role maintaining thi" e'o"#"tem" tro%hi' 4e7, 526 it i" a re"ident "%e'ie"

in the Tagu" e"tuar# and 5$6 7e'au"e it i" highl# u"ed in fi"herie"! The an'hov# life '#'le

i" uite "imilar to the "ardine" '#'le 5R, 18-6!

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/METHODOLOG3

/., State of theArt

*i"h "imulation model" have 7een develo%ed for a""e""ment on fi"herie" and environmental

ualit# management, "imulating fi"h %o%ulation u"ing individual?7a"ed model"

I(M" 5indholm et al, 2001H o4an Cr et al, 1, 2000H o4an Cr et al, 1H Monvoi"in

et al,

1H Ro"e et al, 1H DeAngeli" et al,116!

3%atial modelling of fi"h 4ith individual 7ehaviour 4a" initiated 7# (al'hen" grou%

5(al'hen, 1:- and Reed (al'hen, 182 in i"@e et al, 186! I(M" are 'reated on the

re'ognition that individual" differ in their 'hara'teri"ti'" and a7ilitie" and that "u'h

differen'e" ma# 7e im%ortant in e'olog# and %o%ulation d#nami'"! The"e model" "imulate

the fi"h gro4th in term" of the 7ioma"" variation" or u"ing an energeti'?7a"ed

a%%roa'h 5eve7vre et al 2001H .an"on, 1:6! One of the main feature" of I(M" 4ith regard to

"%atial di"tri7ution" ha" 7een the re'ent develo%ment of "%atiall# e>%li'it model" 5T#ler Ro"e,

1)6, 4hi'h in'or%orate "%atial heterogeneit#, individual varia7ilit# andindividual

movement! One of the %ro7lem" 4ith I(M" i" that the# are little more than a 4a# of

a''ounting for individual" in a %o%ulation! If I(M" are to 7e'ome an im%ortant tool for

e>%laining the 7ehaviour of individual" and %o%ulation", model" that de"'ri7e 4h#

individual" are motivated for a'tion" are needed! Thi" mean" that individual a'tion" "hould

7e vie4ed in the light of 4hat evolution ha" found favoura7le!

It ha" 7een ongoing the develo%ment of "imulation model" for fi"h 7ehaviour 5(reit7urg etal,

1H *i'@"en et al, 18H .eath et al, 18H 3e@ine et al, 1:H 3e@ine et al, 1-H E'@man

et al, 1$H 3e@ine et al, 11aH 3e@ine et al, 1176, in'luding fi"h movement 5M'Dermot

Ro"e, 2000H 3utton et al, 2000H Rail"7a'@ et al, 1H i"@e et al, 186, to %redi't the fi"h

di"tri7ution and the influen'e" of environmental 'ondition" on fi"h "urvival 5indholm et

al,

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2001H M'Dermot Ro"e, 2000H amourou> et al, 1aH amourou> et al, 17HCa4or"@a

et al, 1:6!

The"e "tudie" often in'lude a model of the fi"h 7ioma"" gro4th, de%endent on it" %ro'e""e" offeeding, re"%iration and e>'retion! In fa't, environmental 'ondition" affe't the"e %ro'e""e"

5dire'tl# or indire'tl#6 and "o the"e model" 'on"ider 7iologi'al 'on"traint" 5food uantit#

and

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ualit#, %redator" of the "tudied "%e'ie"6, "#"tem" %h#"i'al?'hemi'al 'ondition"

57ottom material, 4ater tem%erature, 'urrent velo'it#, de%th, di""olved o>#gen, "alinit#,

tur7idit#, ammonia'al nitrogen6 and human?related "tre"" 5fi"hing, %ollution6! &redi'ting

the fi"h 7ioma"" i" mu'h more ina''urate 'om%ared to %redi'ting the 7ehaviour of a fi"h!

There are "o man# fa'tor" affe'ting fi"h gro4th that modelling -0 of the fi"h 7ioma""

'hange i" in fa't a good e"timate 53e@ine, M!personal communication6!

Direct DensityDependence

&o%ulation %ro'e""e" "u'h a" "urvival, gro4th, re%rodu'tion and movement are "aid to 7e

den"it# de%endent if their rate" 'hange a" a fun'tion of %o%ulation a7undan'e! &ro'e""e"that limit %o%ulation gro4th at high a7undan'e" 5e!g! "lo4er gro4th, in'rea"ed emigration, lo4er

"urvival6 or in'rea"e numeri'al gro4th at lo4 %o%ulation a7undan'e" 5e!g! fa"ter gro4th,

in'rea"ed immigration, higher "urvival6 are e>am%le" of dire't den"it# de%enden'e or

compensation! Dire't den"it# de%endent %ro'e""e" o%erate a" a negative feed7a'@ and tend to

"ta7ili=e %o%ulation a7undan'e! If %ro'e""e" "u'h a" "urvival and gro4th de'rea"e at lo4

%o%ulation a7undan'e" or in'rea"e at high a7undan'e", the# are referred to a" inver"e den"it#

de%enden'e or depensation! Inver"e den"it# de%endent %ro'e""e" o%erate a" a %o"itivefeed7a'@ and tend to de"ta7ili=e %o%ulation"!

While 'om%en"ation i" a %o%ulation?level %henomenon, it i" im%ortant to note that it i"

individual re"%on"e" to a7undan'e 'hange" that 'au"e 7oth 'om%en"ator# and de%en"ator#

den"it#?de%enden'e 5Ro"e o4an, 2000H DeAngeli" et al, 116! Individual" in a fi"h

%o%ulation 'om%ete 4ith one another for a limited %ool of environmental re"our'e" vital to

their "urvival and "u''e""ful re%rodu'tion! E>am%le" of the"e environmental re"our'e" are

food, refuge from %redator" and "uita7le "ite" for "%a4ning 5(erdni@ov, 16!

om%en"ation" %rin'i%le i" that the greater the num7er of fi"he" in relation to thi" %ool

of vital re"our'e", the more inten"e the 'om%etition! In'rea"ed inten"it# of 'om%etition for the"e

re"our'e" ma# then e>%re"" it"elf in de'rea"ed "urvival rate", "lo4er gro4th rate", redu'ed

re%rodu'tion or in'rea"ed emigration from the area of 'om%etition! The re"ult i" that ver#

den"e %o%ulation" that e>'eed the availa7le re"our'e" de'line in num7er" until the 'om%etitive

%re""ure i" redu'ed! On the other hand, 4hen %o%ulation a7undan'e i" lo4 in relation to the

availa7le environmental re"our'e", the inten"it# of 'om%etition i" minimi=ed! The re"ult i"

an

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in'rea"e in "urvival, gro4th and re%rodu'tion and a de'rea"e in emigration, 4hi'h o%erate to

in'rea"e %o%ulation a7undan'e!

An in'rement in an e>i"ting mortalit#, or even a ne4 "our'e of mortalit#, im%o"ed on a fi"h

%o%ulation 4ill at fir"t tend to dimini"h the num7er" of fi"hH thi" de'rea"e in num7er" of

individual" 4ill 'au"e a %o%ulation re"%on"e to 'om%en"ate the in'rea"ed mortalit#! The

magnitude of the 'om%en"ator# re"%on"e and the life "tage" in 4hi'h it o%erate" vary among

species, de%ending on their hi"tor# "trateg# 5"urvival, gro4th and re%rodu'tion rate"6, and

'an vary among populations due to "ite?"%e'ifi' 'ondition" 5e!g! environmental

re"our'e" availa7le, food 4e7 arrangement6! Ro"e o4an 520006 'onfirm that the e>i"ten'e of

'om%en"ation i" found in "%a4ner?re'ruit data, em%iri'al "tudie" and al"o in

fi"herie" management! (erdni@ov et a l 516 demon"trated that an'hov# re'ruitment

num7er" in the A=ov 3ea u"uall# greatl# e>'eed "urvivor" from the %reviou" generation,

%re"enting a high "u"taina7ilit# of the %o%ulation in fa'e of unfavoura7le environmental

'ondition" and heav# fi"hing!

The ue"tion of 'om%en"ation i" im%ortant in a""e""ing the effe't" of anthro%ogeni' "tre""or"

on fi"h %o%ulation" 5Ca4or"@a et al, 1:6! .arve"t level" or entrainment and im%ingement

rate" that e>'eed the 'om%en"ator# re"erve of a %o%ulation 4ould 'au"e %o%ulation de'line"!The 'on"euen'e" of overe"timating 'om%en"ation 'an 7e "evereJ %o%ulation de'line to a

"everel# lo4 a7undan'e! To 7e %rote'tive of the re"our'e, %eo%le u"uall# re"ort to the no

'om%en"ation h#%othe"i" unle"" one 'an demon"trate a 'lear and uneuivo'al

under"tanding of the 'om%en"ation me'hani"m 5Ro"e o4an, 20006! Rarel# there i"

"uffi'ient em%iri'al eviden'e to 'om%rehend ho4 the variou" life "tage" and %ro'e""e" 'om7ine to

'au"e the 'om%en"ator# re"%on"e of a %arti'ular %o%ulation! A""uming no 'om%en"ation, or

undere"timating 'om%en"ation, i" e>tremel# %rote'tive of the natural re"our'e" 7ut it lo4er"

e'onomi' effi'ien'# and 'au"e" %otentiall# e>'e""ive and unne'e""ar# finan'ial 'o"t"!

Under"tanding 'om%en"ation at the %ro'e""?level %ermit" to 7ound the magnitude of

'om%en"ation a%%ro%riate to u"e in %o%ulation model"!

Individual?7a"ed modelling offer" a %romi"ing a%%roa'h for modelling %o%ulation and

'ommunit# d#nami'" 5DeAngeli" et al, 116 and ha" feature" that "hould hel% in

uantif#ing 'om%en"ator# re"%on"e" of fi"h %o%ulation"! Re%re"enting lo'al intera'tion" in

"%a'e, "i=e? 7a"ed intera'tion", e%i"odi' effe't", movement and "to'ha"ti'it#, all of 4hi'h are

im%ortant to

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"tage sHgS c

i" the "'o%e for gro4th of

the individual fi"h in the 'la"" c of"tages, 'al'ulated in the &M! g

Sc

Population Growth

Model

WSc

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the individual fi"h "'ale, the IM i" al"o develo%ed! In the near future, 4ith the &M it

4ill 7e %o""i7le to 7uild a model of the fi"h movement a''ording to the

%o%ulation" environmental %referen'e"! *ield o7"ervation" indi'ate that fi"h inha7it

different area" a''ording 4ith their life "tage! Therefore, fi"h %refer different

environmental 'ondition" in ea'h life "tage 5(erdni@ov et al, 16 and thi" "hould 7e

'on"idered in the model of the fi"h movement!

*ig!) %rovide" a "im%lified vie4 of the model! The model 'on"ider" that the individual gro4th

de%end" on food availa7ilit# and 4ater tem%erature! Thi" model 'reate" "erie" of re"ult" of the

individual fi"h" variation of 7ioma"" in time, for ea'h of the "tage" of it" life '#'le!

The"e re"ult" are then treated to e"timate a mean 7ioma"" for ea'h life "tage! In fa't, a" the

&M i" a 'la"" tran"ition model, in thi" %ha"e it i" e"timated mean 7ioma"" value" for

defined 'la""e" of ea'h life "tage! With thi" %ro'edure i" then %o""i7le to 'al'ulate the scope

for growth for the"e mean 7ioma"" value" for ea'h 'la"" of the life "tage" and develo% the &M!

/.2 I0&"&0ua* Growth Mo0e*$IGM%

Thi" "e'tion e>%lain" the 7a"i' euation" u"ed in the Individual ro4th Model 5"ee *ig!+6!

The IM model i" 7a"ed on a 7ioma"" 7alan'e! Thi" model "imulate" the 7ioma"" gro4th

of

an individual fi"h, for ea'h of it" life "tage", 'on"idering the fi"h"meta7oli"m!

Phy Fish

Tw

Is

W

s? W

s

Zoo

Es

VMs

AM

sIGM

*ig!+ Individual ro4th Model! *or the life "tage s, the individual fi"h" 7ioma"" 5#S6 i" variated 7#

the differen'e 7et4een dail# P%rodu'tion 5inge"tion, IS6 and Pde"tru'tion 5ege"tion, E

S,

e>'retion due to the vital meta7oli"m, !"S

and to the a'tive meta7oli"m, A"S6 and

thi" differen'e i" the individual fi"h" 7ioma"" variation $% #S6! Inge"tion i" a fun'tion

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of 4ater tem%erature 5w6 and food availa7ilit# 5%h#to%lan@ton, Phy and =oo%lan@ton,&oo6 and the e>'retion 5!" and A"6 i" a fun'ion of the fi"h" 7ioma"", food availa7ilit#and 4ater tem%erature!

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Thi" model u"e" modified euation" of the 3hallo4?3ea E'ologi'al Model 53e@ine et al,

11a6! The 7ioma"" gro4th i" de"'ri7ed a" follo4"J

W

I Et

KM AM 516

4here # i" the individual fi"h" 7ioma"" 5mg!individual?16, I i" the amount eaten or

inge"tion 5mg!d?16, E i" the ege"tion, i!e! the amount of inge"ted food that" not

a""imilated 5mg!d?16 and !"'A" i" the e>'retion 'om%onent, i!e! the lo""e" of

7ioma"" due to the fi"h" meta7oli"m, 4here !" i" the vital meta7oli"m 5mg!d?16

and A" i" the a'tive meta7oli"m 5mg!d?16! M'Dermot Ro"e 520006 develo%ed an

individual?7a"ed model to %i"'ivore "to'@ing 4here the gro4th fun'tion al"o u"e" the"e

t4o meta7oli' lo""e" of fi"h 7ioma""! The

inge"tion i" given7#J

I Ima>9i

!W9a

!Wfood

526

Wfood 9"

4here Imax i" the ma>imum inge"tion rate or ma>imum gro4th rate 5d?16, (i i" a

"tage? "%e'ifi' inge"tion 'oeffi'ient, (a i" a "tage?"%e'ifi' 'oeffi'ient that tran"late" the

"'o%e of 7ioma"" gro4th in the "%e'ifi' "tage, #food i" the num7er of availa7le %re#" or

food amount 5individual"!?16 and (s i" the half?"aturation 'on"tant 5individual"!?

16! The ma>imum

inge"tion rate i" a fun'tion of 4atertem%eratureJ

Im a> 97!e>%5 9'!T46

5$6

4here (b i" the ma>imum inge"tion rate at 0 5d?16, (c i" a tem%erature 'on"tant 5?16and

w i" the 4ater tem%erature 56!

The amount of availa7le food #food, i" 'al'ulated a" follo4" 7#J

#food&

wp

P % !&

wp

5)6

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4here & i" the %re# 'on'entration, wp i" the 4eight of one individual %re# 5mg!%re#?16, P

i" the 'on'entration of %h#to%lan@ton in the environment 5mg!?16, & i" the

'on'entration of

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=oo%lan@ton in the environment 5mg!?16 and % i" a 'oeffi'ient of =oo%lan@ton inta@e 7#

the individual fi"h, de%endent on the fi"h "i=e!

De"tru'tion %ro'e""e" %re"ented in euation 516 are given

7#J

E Q I ! 51 ? 9E6 5+6

KM Q W ! 9KM

5-6

AM Q I ! 9AM

5:6

4here (E

i" the net a""imilation effi'ien'#, (!"

i" the vital meta7oli"m 7ioma""

'on"um%tion rate 5d?16 and(A"

i" the a'tive meta7oli"m e>'retion rate!

All the euation" are develo%ed for the larvae, Buvenile and adult "tage"! In the egg

"tage, there i" no inge"tion and ege"tion, vital meta7oli"m and a'tive meta7oli"m are

'on"idered null, re"ulting in no gro4th! Ea'h of the life '#'le" "tage" 5egg, larvae, Buvenile

and adult6 %re"ent" different 'hara'teri"ti'" in the %h#"iologi'al %ro'e""e" and "o

thi" model 'ontem%late" tho"e differen'e" 7# 'on"idering "tage?"%e'ifi' 'oeffi'ient" value"

for ea'h of the four "tage" of the fi"h" life '#'le!

/.2., Itera!t&o 4etwee f&(h a0ha4&tat

The fi"h intera't" 4ith ha7itat 7# feeding and e>'reting! In thi" model, %h#to%lan@ton and

=oo%lan@ton 'on"titute de fi"h food 5or %re#6, and it i" 'on"idered that there i" al4a#"enough food in the "#"tem for thi" "ingle fi"h! Thi" model a""ume" that there i" a de%enden'e

7et4een the %re# "i=e and the fi"h "i=e, 'on"idering that the fi"h 'an eat %h#to%lan@ton

"in'e the 7eginning of the larval "tage, 7ut the amount of =oo%lan@ton inta@e in'rea"e"

4ith the fi"h "i=e and hen'e the fi"h" age, if one 'on"ider" that the fi"h ha" a gro4th 4here

higher 7ioma"" i" euivalent to more age!

In the IM model, the de"tru'tionS %ro'e""e" are ege"tion 5E6 and e>'retion due to vital

and a'tive meta7oli"m" 5!" an A"6! (oth ege"tion and a'tive meta7oli"m are "imulated a"

%artial lo""e" of the inge"ted %re# 7ioma""! The ammonia %rodu'tion ma# 7e %redi'ted from the

vital meta7oli"m 'on"um%tion of fi"h 7ioma""! Organi' matter in%ut" to the environment

ma# 7e

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'al'ulated from the non?a""imilated food 5ege"tion6 and the a'tive meta7oli"m

'on"um%tion of 7ioma""!

/.5 Popu*at&o GrowthMo0e*

The %o%ulation d#nami'" i" "imulated through a modifi'ation of a 'la"" tran"ition model

5*erreira et al, 18 in 3ima" et al, 2001H (erdni@ov et al, 16! Thi" model 'on"ider" the

fi"h" four "tage" of it" life '#'leJ egg", larvae, Buvenile" and adult", ta@ing into a''ount

the individual "tage?"%e'ifi' 7iologi'al %ro'e""e"! In ea'h "tage there are "everal 'la""e"

and "o

the model 'on"ider"J

#toLEggs

!?

"?

#?

$

meggs

mL$

mL%

mL&

mL'

A# ? A" ? A! ? %&% toO'#

?'"

?'!

m*& m *% m *$ m*om& m% m $

PGM

*ig! -! &o%ulation ro4th Model" 'la""e" for ea'h "tage 5one 'la"" for the egg", four 'la""e" for larvae "tage,), three 'la""e" for the Buvenile "tage, * and four 'la""e" in the adult "tage, A, 7eing ++ the oung?of?the?earindividual"6, 4ith 'hara'teri"ti' mortalit# for ea'h 'la"", m and tran"ition of "tage" rate" 5Eto), )to* and

*to++, tran"ition of egg" to larvae, larvae to Buvenile" and Buvenile" to adult" #oung?of?the?#ear,re"%e'tivel#6!

The tran"ition of the num7er of individual" of the fi"h %o%ulation between classes in ea'h of

the "tage" of the life '#'le i" given 7#J

n3

t

n3

t !g3

"

m3

!n3

586

4here n i" the num7er of individual" of "tage s and 'la"" c, g i" the "'o%e for gro4th of "tages

,a

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and 'la"" c 5d?16, m i" the mortalit# rate of "tage s and 'la"" c 5d?16 and t i" time 5d6!Therefore,

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the num7er of individual" in ea'h 'la"" de%end" on the individual scope for growth and on

a natural mortalit# rate! *ig!: illu"trate" ho4 the num7er of individual" varie" along the life

"tage a''ording to Euation 586! Thi" model 'on"ider" onl# the natural mortalit# rate, 7ut

in the future it 4ill develo% to 'on"ider human %re""ure on the %o%ulation 5e!g!

fi"hing,

%ollution6!

nn

egg"

nlarvae

nBuv eni le

nadult"

egg" larvae Buvenile" adult"sc

*ig!: Kariation of the num7er of individual" %er "tage of the fi"h life '#'le! In ea'h "tage there i" a meannum7er of individual"! One of the rea"on" for 'on"idering "everal 'la""e" %er "tage i" that it greatl# dimini"he"

the error in the e"timate of the"e num7er" of individual"!

The "'o%e for gro4th,g i" de"'ri7ed a"J

I E S !"g

- --

ws ws

A"- 56

- 1 -

4here IS

, i" inge"tion 5mg!d?16, ES

i" ege"tion 5mg!d?16, !"S

i" vital meta7oli"m

5mg!d?16 and A"S

i" a'tive meta7oli"m 5mg!d?16 in the 'la"" c of "tage sH wsc

and wsc'

are the mean 4eight" of the individual fi"h 5mg6 in the 'la"" c and c', re"%e'tivel#!

Mean 4eight" of

ea'h 'la"" are e"timated from the time "erie" of the 7ioma"" re"ult" "imulated 7# IM

and inge"tion, vital meta7oli"m and a'tive meta7oli"m are 'al'ulated a" in IM 7ut u"ing

mean 7ioma"" value" in ea'h 'la""!

The tran"ition between stages i" "imulated 'on"idering that it i" reuired a %eriod of time

for the develo%ment of the fi"h in ea'h "tage! *i"h need a %eriod of time in the "tage of

larvae 7efore 7eing Buvenile" and "o on! Neverthele"", a" thi" i" a %o%ulation gro4th

model, fi"h

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arent all in the "ame "tage in a given moment in time, e>i"ting egg", larvae, Buvenile"

and adult" at the "ame moment and in ea'h "tage there are individual" more develo%ed than

other"!

Therefore it i" rea"ona7le to 'on"ider a tran"ition rate 5stos'6, a" follo4"J

" to " 1"

ft

"

5106

4ith sf

7eing the la"t 'la"" of "tage s 5egg", larvae or Buvenile"H never the "tage adults,

"in'e thi" i" the la"t "tage of the life '#'le6 and ts

the 'hara'teri"ti' duration of the

"%e'ifi' "tage 5teggsQ2 d, tlarvaeQ$1 d, t/uvenilesQ$$0 d6! A" "een in *ig!- there i" a tran"ition

of egg" to larvae,Eto), larvae to Buvenile",)to* and Buvenile" to adult",*to++!

3%a4ning i" a fun'tion of the num7er of individual" in ea'h 'la"" of the adult "tage,

nAc

J #oung?of?the?#ear, A1#ear, A2#ear" and A$#ear" 5num7er of adult"6 and of ea'h

'la""" effe'tive "%a4ner" 5not all fi"h are a7le to "%a4n6, %rovided there i" a "%e'ifi'

7at'h "i=e for ea'h fi"h "%e'ie"! Effe'tive "%a4ner" of 'la"" c i" the %er'entage of fi"h in

the 'la"" c that are a'tuall# a7le to "%a4n 5the a7ilit# to "%a4n de%end" on the fi"h"

"e> and re%rodu'tive

maturit#6J

Spawning 0S!S

E c

!nAc

5116

4here 0S i" the 7at'h "i=e 5egg"!individual?16, SEc

i" the num7er of effe'tive "%a4ner" in

the 'la"" c and nAc

i" the num7er of individual" in 'la"" c of the adult "tage! In the &M

"%a4ning %eriod o''ur" in A%ril/Ma# and hen'e the "%a4ning i" of 1 time %er #ear!

Mortalit# flu'tuate" along the life '#'le! In fa't, egg" and larvae %re"ent the highe"t

natural mortalitie" 5indholm et al, 2001H Ca4or"@a et al, 1:H DeAngeli" et al, 116! In thi"

model ea'h 'la"" of ea'h "tage %re"ent" a 'hara'teri"ti' mortalit#, "o that in the overall

%o%ulation there i" a mortalit# rate 'urve a" de"'ri7ed 7# *ig! 10!

/.5., Itera!t&o 4etwee f&(h popu*at&oa0 ha4&tat

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The fi"h %o%ulation intera't" 4ith ha7itat 7# feeding and e>'reting! on'erning the

d#nami'" of the fi"h %o%ulation %redation over the %h#to%lan@ton and =oo%lan@ton in the

e'o"#"tem thi"

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model 'on"ider" variation" of the %re# 'on'entration throughout the #ear and ho4 it

affe't" the %o%ulation" gro4th! In fa't, thi" influen'e i" in'luded in the individual gro4th

model, that %rodu'e" the re"ult" from 4hi'h it i" then 'al'ulated ea'h "tage" mean 7ioma""

and al"o in the %o%ulation gro4th model, in the inge"tion and de"tru'tion %ro'e""e"

'al'ulu"! Thi" model a""ume" that the fi"h %o%ulation i" not a7le to redu'e e>ten"ivel# the

%h#to%lan@ton and =oo%lan@ton" 'on'entration" in the "#"tem and therefore the "tarvation?

indu'ed mortalit# i" not mea"ured!

The organi' matter and ammonia %rodu'tion 7# the fi"h %o%ulation i" ea"il# e"timated from

the &M re"ult" for the ege"tion and a'tive meta7oli"m 5organi' matter6 and vital meta7oli"m

5ammonia6 %artial 'on"um%tion of fi"h" 7ioma"", multi%lied 7# the num7er of individual" in

the %o%ulation! A" thi" model 4ill 7e integrated in the MO.ID "#"tem 5for more

information "ee "e'tion A!16 in the near future, it i" im%ortant to in'lude the fi"h

%o%ulation" in%ut of ammonia and organi' matter in the environment!

/.6 F&(h7o"e7et

Movement rule" are a 'riti'al 'om%onent of "%atiall# e>%li'it I(M" 7e'au"e movement i"

an e""ential %ro'e"" u"ed 7# fi"h to ada%t to 'hanging environment and 'om%etitive

'ondition"! In fa't, fi"h move to im%rove food inta@e and gro4th, to redu'e vulnera7ilit#

to %redation ri"@" that var# 4ith fi"h "i=e and environmental 'ondition", to "ee@ "helter

during high flo4" and avoid "tranding a" flo4" de'rea"e, and to avoid 'om%etition 4ith

dominant fi"h! Model" mu"t 7e a7le to "imulate the"e movement" 'orre'tl# if the# are to

7e u"eful for %redi'ting %o%ulation re"%on"e" to 'hange" in ha7itat, mortalit# rate" or'om%etition 5Rail"7a'@ et al,

16! *urthermore, verif#ing that movement rule" %rodu'e reali"ti' movement de'i"ion"i"

one of the model evaluation "te%" needed for I(M" to 7e a''e%ted for de'i"ion?ma@ing and

re"ear'h!

Rail"7a'@ et al 516 "tudied fitne"" mea"ure" and movement rule", in "tream fi"h I(M"!

3%atiall# e>%li'it I(M" u"e movement rule" to determine 4hen an animal de%art" it"

'urrent lo'ation and al"o to determine it" movement de"tination! The"e rule" generall#

'om%are lo'ation" u"ing "ome mea"ure" of a fi"h" e>%e'ted fitne"" and a""ume that

fi"h ma@e

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movement de'i"ion" at lea"t in %art to in'rea"e their fitne""! Movement rule" are 'riti'al

to reali"ti' "imulation of ho4 individual", and therefore %o%ulation", re"%ond to 'hange" in

ha7itat and %o%ulation den"it#! Re'ent re"ear'h "ho4" that man# fi"h move ui'@l# in

re"%on"e to 'hange" in %h#"i'al and 7iologi'al 'ondition", "o movement rule" "hould allo4

fi"h to ra%idl# "ele't the 7e"t lo'ation that i" a''e""i7le! Regarding movement rule",

Rail"7a'@ et al 516 'on'luded that 516 I(M" "hould a""ume that the fi"h are familiar

4ith their "urrounding" over an area greater than their 'urrent lo'ation 5model" "hould let

fi"h move an# time that 7etter ha7itat i" availa7le 4ithin the area the# are familiar 4ith6

and 526 model" "hould let fi"h "ele't the 7e"t ha7itat availa7le in"tead of moving randoml#!

If routine non? e>%lorator# movement i" "imulated a" %artiall# random, it "hould o''ur over

a 'on"idera7l# "maller time "'ale than ha7itat variation!

*itne"" mea"ure" are u"ed in movement rule" to rate alternative de"tination"! The theor# that

minimi=ing the ratio of mortalit# ri"@ to food inta@e ma>imi=e" a fi"h" fitne"" i" not

a%%li'a7le to t#%i'al I(M movement de'i"ion" and 'an 'au"e "eriou" error" in 'ommon

"ituation"! In"tead, Rail"7a'@ et al 516 develo%ed fitne"" mea"ure" from unified foraging

theor# that are theoreti'all# 'om%ati7le 4ith I(M"! Thi" fitne"" 'au"e" fi"h to "ele't

ha7itat that ma>imi=e" it" e>%e'ted %ro7a7ilit# of "urvival over a "%e'ified time hori=on,

'on"idering 7oth "tarvation and other ri"@"! Thi" fitne"" mea"ure i" de%endent on the fi"h"'urrent "tate, ma@ing fi"h 4ith lo4 energ# re"erve" more 4illing to a''e%t ri"@" in e>'hange

of higher food inta@e! Another mea"ure re%re"ent" the e>%e'tation of rea'hing re%rodu'tive

maturit# 7# multi%l#ing e>%e'ted "urvival 7# a fa'tor indi'ating ho4 'lo"e to the "i=e of

fir"t re%rodu'tion the fi"h gro4" 4ithin the time hori=on!

3e@ine et al 511a, 117, 1:6 "tudied fi"h movement" a''ording to their environmental

fa'tor"! U"ing an o7Be't?oriented %rogramming language, the# develo%ed the 3hallo4?3eaE'ologi'al Model 533EM6, 4hi'h "imulated fi"h movement a''ording to their %referen'e for

environmental 'ondition" a" 4ell a" 'om%etition among "%e'ie"! The movement 'om%onent

'on"idered adve'tion and diffu"ion and al"o the movement 7# "4imming! The "4imming

of living organi"m" 4a" 'au"ed 7# their %referen'e" and the 'riteria to de'ide the

movement 4ere food amount, de%th, 4ater tem%erature and the nature of the "ea 7ottom!

ater, 3e@ine et al 51:6 develo%ed a model of fi"h di"tri7ution a''ording to the fi"h

%referen'e for environmental fa'tor" "u'h a" 4ater tem%erature, de%th, 'over, "hade,

'urrent

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velo'it#, tur7idit#, food amount, 7ioma"", "tem of auati' %lant" and 'om%o"ite 'ondition"!

In thi" model the %arameter value" for the environmental %referen'e and the 4eight value" of the

environmental fa'tor" 'ould 7e introdu'ed 4ithout 'ali7rating the %referen'e %arameter"

again! Thi" model" 'ali7ration de%ended on e>%erimental "imulation"! In the"e

e>%eriment", a determined num7er of fi"h 4a" %la'ed in tan@" and "everal environmental

'ondition" 4ere te"ted to mea"ure fi"h %referen'e" 5in term" of their di"tri7ution in the tan@6!

indholm et al 520016 modelled fi"h movement a''ording to ha7itat 'om%le>it#, u"ing a

"im%le %o%ulation model 4ith a modified (everton?.olt euation to "imulate the effe't" of

ha7itat?mediated %ro'e""e" on %o%ulation re"%on"e" at the land"'a%e "'ale! It 'on"ider" a

%o%ulation "u7divided into n region", 4here ea'h region i" re%re"ented 7# a %arti'ular level of

ha7itat 'om%le>it#! .a7itat 'om%le>it# i" inter%reted a" a mea"ure of the verti'al relief and

'over from %redation %rovided 7# a %arti'ular "u7"tratum 5e!g! %e77le?'o7le, "and, 7oulder6

and an# a""o'iated emergent e%ifauna 5e!g! "%onge", am%hi%od tu7e", 'erianthid anemone",

"hell de%o"it", 7iogeni' de%re""ion"6! It al"o 'on"ider" that ha7itat 'om%le>it# i"

uniform

4ithin an# region and that ea'h region i" either a marine %rote'ted area in 4hi'h nofi"hing

di"tur7an'e o''ur" or thatti i" out"ide a marine %rote'ted area and altered 7# fi"hing a'tivit#!

In indholm et al model net %er?month movement 7et4een region" i" a fun'tion of the

%er'entage" of individual" moving 7et4een region" and it i" "%e'ified that movement rate"

are the inver"e of a ha7itat 'om%le>it# "'ore! indholm et al 520016 'on'luded, among

other thing", that movement rate" 4ere 'riti'al for %redi'ting the effe't" of marine

%rote'ted?area "i=e on fi"h "urvival!

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2 MODELIMPLEMENTATION

2., I0&"&0ua* GrowthMo0e*

The 'on'e%tual model of the Individual ro4th 5IM6 u"e" the Tagu" e"tuar# a" the 'a"e

"tud# and Engraulis encrasicolus a" the "tudied fi"h "%e'ie"! The model 4a" im%lemented

u"ing the &o4er"imTM "oft4are! A fir"t "en"itivit# anal#"i" i" done, 'on"idering

the environmental varia7le" 5%h#to%lan@ton, =oo%lan@ton and tem%erature6 'on"tant" in

"%a'e and time!

Thi" model u"e" tem%oral "erie" of %h#to%lan@ton and =oo%lan@ton 'al'ulated 7# &ina

520016 for a 'entral area in the Tagu" e"tuar# and the"e re"ult" are in good agreement 4ith field

mea"urement"! &ina" re"ult" indi'ated that the dail# mean 'on'entration" of

%h#to%lan@ton

and =oo%lan@ton 4ere de"'ri7ed throughout the #ear a" "ho4n in the 'urve" of*ig!8!

$.%

$./

/.0

/.1

/.'

/.%

/./ / &/ 1/ 2/ $%/ $3/ $0/ %$/ %'/ %4/ &// &&/ &1/

ti(e )days*

*ig! 8! Dail# mean 'on'entration 5mg!?16 of %h#to%lan@ton and =oo%lan@ton for the #ear 1 ina 'entral 7o> of the Tagu" e"tuar# 5&ina, 20016!

The IM "imulate" the gro4th of the individual fi"h in ea'h of it" life "tage"! The

%arameter" u"ed in the individual gro4th model" are %re"ented in Ta7le!1, re"ulting from

the 'ali7ration of the model after introdu'ing "ome t#%i'al value" %re"ented 7# 3e@ine

51176 and #%en" et al 520016!

g+

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Ta7le !1 &arameter value" u"ed in the IM!

Name

9i 9a 97 9' T4

W% 9"

2./ Popu*at&o GrowthMo0e*

The 'on'e%tual model of the &o%ulation ro4th 5&M6 u"e" the Tagu" e"tuar# a" the

'a"e "tud# and Engraulis encrasicolus a" the "tudied fi"h "%e'ie"! The model 4a"

im%lemented u"ing the &o4er"imTM "oft4are! *ir"t, the &M 4a" te"ted 4ith "everal

"imulation" 4ith different initial 'ondition" for the num7er of individual" in ea'h 'la""

of the fi"h %o%ulation and no irregularitie" 4ere found in the re"ult"! *or that rea"on it

i" 'ho"en that the %o%ulation initial num7er of individual" i" of 1+0!000 egg" 5the "ame

num7er of egg" a" in an individual 7at'hH thi" value i" 'onfirmed 7# Melo, 1)6!

In the %o%ulation gro4th model, individual mean 4eight" ne'e""ar# for the scope for growth

e"timate in ea'h 'la"" of ea'h life "tage, are given 7# the IM re"ult" 5"ee *ig!7 for

individual mean 4eight" G the mean value" are 'al'ulated u%on the 7ioma"" 'urve

throughout the life '#'le illu"trated in *ig!a6! Inge"tion and de"tru'tion %ro'e""e" aree"timated a" in the IM 5u"ing the value" %re"ented in Ta7le!16, 7ut u"ing the mean 7ioma""

value"!

The &M u"e" a 'hara'teri"ti' mortalit# rate for ea'h 'la""! The &M "imulation"

'on"ider the 'urve of *ig!10 and %lu" t4o different "ituation" of higher mortalit# rate" in the

adult "tage 5"ee Ta7le!2, "'enario" $ and )6! In the fir"t fe4 da#" of life, fi"h fa'e an

inten"e mortalit#, either 7e'au"e the# are driven 7# the 'urrent" and therefore ma# end u% in%la'e" too adver"e 5in the "tage of egg and the

1and

2'la""e" of the larvae "tage6, either

7e'au"e the# are too #oung and dont @no4 ho4 to find food or ho4 to e"'a%e from

%redator" 5larvae "tage6! In the

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egg "tage onl# 10 of the egg" "urvive and in the larvae "tage there i" a total mortalit#of

+ in one?month %eriod! A''ording to R 518-6 in the fir"t %eriod of life fi"h ma# %re"ent

-0?100 mortalit# rate"! At the end of their life '#'le, fi"h %re"ent a higher mortalit#

rate 7e'au"e the# %re"ent a higher ri"@ of d#ing of age and/or di"ea"e" 5in the 'la"" A$6!

a*

$%//

$///

0//

1//

'//

%//

/

/ &1/ 4%/ $/0/ $''/

ti(e )days*

,*

$%//

$///

0//

1//

'//

%//

/

L$ L% L& L' $ % & *o *$ *% *&

+lass

*ig! a6 IM re"ult" for a "imulation of the an'hov#" 7ioma"" gro4th in the Tagu" e"tuar# for ) #ear",

%roviding the individual fi"h 7ioma"" 5mg6! *rom the"e re"ult" it i" %o""i7le to 'al'ulate the 76 mean individual4eight of an individual fi"h in ea'h 'la"" of the "tage" of larvae, Buvenile and adult u"ed in the &M! om%aring'urve" a6 and 76 it i" 'on'luded that 76 re%re"ent" the 7ioma"" mean value" throughout all the fi"h" life "tage"!

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*our different "'enario" are develo%ed to te"t the &M model 5"ee Ta7le!26! 3'enario 1 i" an

ideal "ituation 4ithout environmental or anthro%ogeni' "tre""e"H "'enario 2 i" a "ituation

4ith a le"" re%rodu'tive %o%ulation 5due to environmental "tre""6, 4here the num7er of

"%a4ner" in the adult" "tage i" le"" "ignifi'antH "'enario $ i" a "ituation 'on"idering

anthro%ogeni' "tre""e" 5e!g! fi"hing6 over all the 'la""e" of the adult "tage, re%re"ented 7# a

mortalit# 10 time" higher than in "'enario 1H "'enario ) i" a modifi'ation of "'enario $,

'on"idering fi"hing "tre"" over

the adult 'la""e" e>'e%t for the #oung?of?the?#earindividual"!

$./

/.2

/.0

/.4

/.1

/.3

/.'

/.&

/.%

*ig! 10! Mortalit# rate" u"ed in the

&M for ea'h 'la""!

/.$

/./

#ggs L$ L% L& L' $ % & *o *$ *% *&

+lass

Ta7le!2 &M %arameter" value" and "tate varia7le" initial value"! The"e value" re"ult from the 'ali7ration of themodel after introdu'ing "ome t#%i'al value" %re"ented 7# Melo 51)6, R 518-6 and .enriue a7ral5pers.com6!

1+0000

0,1

0,2

0,20,2

0,

0,)

0,1

0,08

0,01

0,008

0,008

0,008

0,001

0,0010,001

0,00+ 0,0 5 0,05

(33E#o#

3E A13

E A2

3E A$ mE

m1

m2

m$

m)

mA#o#

mA1

mA2

mA$

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5 RESULTS ANDDIS-USSION

5., I0&"&0ua* GrowthMo0e*

The IM 4a" 'ali7rated and "imulation" "tarting in A%ril 4ith the %arameter" value"

%re"ented in Ta7le!1 %rovide the re"ult" di"'u""ed in thi" "e'tion!

Thi" model %rodu'e" the individual fi"h" 7ioma"" throughout it" life '#'le 5*ig!a6 in

a''ordan'e 4ith the e>%e'ted! (efore the adult "tage 5fir"t $-0 da#"6 fi"h %re"ent an

e>%onential gro4th ? a 'on"idera7le %art of the inge"ted food allo4" the in'rea"e of theindividual" 7ioma"" and not onl# the individual" "urvival! In addition, thi"

e>%onential gro4th %re"ent" "'o%e variation" due to the "ea"onal variation" in food

availa7ilit#! In the adult "tage 5after $-0 da#"6 the inge"ted food tend" to 7e 'om%letel#

'on"umed 7# the fi"h" vital and a'tive meta7oli"m" and therefore the o"'illation" in the 7ioma""

re"ult from "ea"onal variation" in food availa7ilit#! There i" the e>'e%tion of the #oung?of?the?

#ear adult" 5the fir"t "eme"ter of the "e'ond #ear 5i!e! da#" $-0 to +)06 that %re"ent an

e>ten"ive gro4th, 4hi'h i" in a''ordan'e to 4hat it i" u"uall# o7"erved in the field!

on"idering that 'ar7on 7ioma"" 5mg6 re%re"ent" )0 of the fi"h" dr# 4eight 5mg d46

and that fi"h" dr# 4eight i" 10 of it" 4et 4eight 5mg 446, multi%l#ing the IM

individual" 7ioma"" re"ult" 7# a fa'tor of 2+ %rovide" the fi"h" 4et 4eight! Therefore,

a''ording to the IM re"ult" 5"ee *ig!a6, an adult fi"h 4eight" 2:,) g 44 510+ mg6,

4hi'h i" in agreement 4ith field o7"ervation" 52+ to $0 g 44 ? Dr! .enriue a7ralpers. com.6!

on'erning the larval gro4th the model 'on"ider" the larvae meta7oli"m a" "ho4n in

*ig!11! The area 7et4een the Inge"tion and De"tru'tion 'urve" give" the larvae 7ioma""

gro4th! De"tru'tion %ro'e""e" are di"'riminated 4ith re'tangular unfilled mar@"

5ege"tion, a'tive meta7oli"m and vital meta7oli"m6! The vital meta7oli"m 'on"ume of

7ioma"" i" the highe"t, after half of the larval "tage" %eriod! .o4ever, in the fir"t 1: da#",

ege"tion %la#" the main role of the de"tru'tion %ro'e""e"!

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%.0

%.'

% IngestionL

$.1

5estructionL

$.%

/.0

#gestionL

*ctM eta"olis mL

VitMeta"olismL

/.'

/

/ 3 $/ $3 %/ %3 &/ &3

*ig!11 arvae Meta7oli"m!

In the Buvenile "tage there i" an im%ortant 7ioma"" gro4th ? at the end of thi" "tage the

fi"h" 7ioma"" i" a7out 80 time" higher than at the end of the larval "tage 5"ee *ig!a,76!

A" thi" "tage %re"ent" a 'hara'teri"ti' time higher than that of the larvae, "ea"onal variation" in

%h#to%lan@ton and =oo%lan@ton are relevant a" o7"erved in *ig!12 ? there i" a %eriod

during 4inter 4hen inge"ted food i" not enough to "u%%l# the fi"h" de"tru'tion

%ro'e""e" and

therefore for'ing a 'on"um%tion of the fi"h"

7ioma""!

1/

3/

'/Ingestion

5estruction

&/ #gestion

%/ *ctMeta"olism

VitMeta"olism$/

/

&/ 1/ 2/ $%/ $3/ $0/ %$/ %'/ %4/ &// &&/ &1/

ti(e )days*

*ig!12 Cuvenile meta7oli"m!

A" e>%lained earlier, the adult meta7oli"m i" "ome4hat different of that o7"erved in the

%reviou" "tage" 5"ee *ig!1$6! In the fir"t "i> month" of the adult "tage 5the oung?Of?the?

ear 'la"" in the %o%ulation gro4th model6 there i" a "ignifi'ant 7ioma"" gro4th 4hen the

fi"h attain" it" fir"t maturit# age! At the "ame time there i" an im%ortant in'rea"e

in the

-i

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individual" vital meta7oli"m" 'on"um%tion of 7ioma"", thu" %reventing further gro4th

4ith the "ame "'o%e!

The adult "tage la"t" for a7out three #ear" and 'on"euentl# the 4inter 'olla%"e" of food

availa7ilit# i" ver# evident 5'om%are *ig!1$ 4ith *ig!1)6! In the"e %eriod", inge"tion

de'rea"e" to a %oint 4here de"tru'tion %ro'e""e" are higher, 4hi'h 'au"e" the individual"

7ioma"" to

de'rea"e in tho"e %eriod" 5a" o7"erved in*ig!a6!

0/

Ingestion*4/

5estruction*

1/ #gestion*

3/ *ctMeta"olism*'/

VitMeta"olism*

&/

%/

$/

/

&1/ 3'/ 4%/ 2// $/0/ $%1/ $''/

ti(e )days*

*ig!1$ Adult meta7oli"m!

$.1

$.'

$.%

6oodL

$ 6ood

/.0

/.1

6ood*

/.'

/.%

/

/ $0/ &1/ 3'/ 4%/ 2// $/0/ $%1/ $''/

ti(e )days*

*ig!1) Availa7le food for larvae 5*ood6, Buvenile 5*oodC6 and adult 5*oodA6!

(g+-in

g

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Running the IM model 4ith the %arameter" value" %re"ented in Ta7le!1 7ut u"ing a "erie"

of food amount in the environment of five times smaller of that "ho4n 7# *ig!8 5dail#

mean 'on'entration" of %h#to%lan@ton and =oo%lan@ton6 'au"e" a "maller individual

7ioma"" gro4th, a" illu"trated in *ig!1+, 4hi'h i" in agreement 4ith 4hat it 4ould 7e

e>%e'ted! .ere it i" 'lear the model 'on"train of the fi"h" gro4th 4ith the availa7le food

amountJ le"" food

availa7ilit# 'au"e" lo4ergro4th!

2//

0//

4//

1//

3//

*ig! 1+ Individual fi"h 7ioma""5mg6 ? IM re"ult" for a"imulation of the an'hov#"7ioma"" gro4th in the Tagu"e"tuar# for ) #ear", u"ing "erie"of food amount five time""maller than that "ho4n 7#*ig!8!

'//

&//

%//

$//

// &1/ 4%/ $/0/ $''/

ti(e )days*

Another environmental fa'tor 'on"idered 7# the IM model i" the 4ater tem%erature

5w6, al"o of great im%ortan'e to the fi"h" gro4th! The euro%ean an'hov# 4ith"tand"

tem%erature" ranging from - to 2! om%aring the IM re"ult" of the individual

7ioma"" gro4th 'on"idering a Tw of 10C 5*ig!1-6, 4ith the re"ult" o7tained 4ith a w of

18 5*ig!a6, and all the other %arameter" remaining the "ame 5Ta7le!16, it i" evident

that 4hen the 4ater

tem%erature get" 'lo"er to the limit, the fi"h" gro4th i"lo4er!

$%//

$///

0//

*ig! 1- Individual fi"h 7ioma""5mg6 ? IM re"ult" for a"imulation of the an'hov#"

7ioma"" gro4th in the Tagu"e"tuar# for ) #ear", 4ith 4atertem%erature of 10!

1//

'//

%//

// &1/ 4%/ $/0/ $''/

ti(e )days*

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5./ Popu*at&o GrowthMo0e*

The &M 4a" "imulated for five #ear" to develo% different "'enario", "tarting 4ith a%o%ulation of 1+0!000 egg" 5the euivalent to one individual 7at'h G Melo, 1) ?, not

re%re"entative of real life "#"tem", 7ut it fa'ilitate" the inter%retation of the re"ult"6! In the

&M, inge"tion and de"tru'tion %ro'e""e" are 'on"idered a" in the IM, 7ut u"ing the

mean 7ioma"" value" 'al'ulated from the individual 7ioma"" IM re"ult" 5"ee *ig!76! The defined

'hara'teri"ti' mortalit# rate" 5"ee *ig!106 are a @e# element in the model, a" it 4ould 7e

e>%e'ted!

5./., L&fe -#!*e & the F&(hPopu*at&o

There i" an in%ut of 1+0!000 egg" and the num7er of egg" ra%idl# de'rea"e" to =ero 7e'au"e

mortalit# in thi" "tage i" ver# high 5mEQ0,6 and 7e'au"e the 'hara'teri"ti' time of thi"

"tage i" of 2 da#" G the "urvivor" "hift to the larvae "tage 5*ig!1:a, *ig!18a, *ig!1a,

*ig!20a6! The"e re"ult" ma# 7e ver# u"eful 4hen modelling fi"h movement" a''ording to their

environmental %referen'e" in time "'ale" "maller than 1 #ear! When modelling fi"h

movement it i" %o""i7le to o7"erve the im%ortan'e of 'urrent" variation" throughout

the #ear, "in'e fi"h in the egg "tage move 4ith the 4ater 'urrent"! Month?to?month

'urrent" variation" 'au"e different larvae "ettlement and 'on"euentl# lead to different level"

of "urvival!

In the larvae "tage the 'hara'teri"ti' mortalit# rate" de'rea"e from 1 to ) 5from 0,) to 0,01

G "ee *ig!106 and therefore the num7er of individual" in 'la"" 1

i" 'on"idera7l# higher

than that of 'la""e" 2,

$and

), a" illu"trated in *ig!1:7, *ig!187, *ig!17 and *ig!207!

When moving u% to the Buvenile" and adult" "tage, the food availa7ilit# 'on"traint %la#" an

im%ortant role 5"ee *ig!1:',d, *ig!18',d, *ig!1',d, *ig!20',d6! In fa't, the "ea"onal variation"

in the amount of availa7le food, determined 7# the %h#to%lan@ton and =oo%lan@ton

'on'entration" in the "#"tem, for'e variation" in the "'o%e for gro4th, and thu" the num7er

of fi"h in ea'h 'la""! *rom "tage" C1

to C$

the num7er of individual" de'rea"e" due to ea'h

'la""" 'hara'teri"ti' mortalit# and the "hift" to the ne>t 'la""! In the adult "tage

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ho4ever, de%ending on the 'hara'teri"ti' mortalit# 5referen'e "'enario or

anthro%ogeni' "tre"" "'enario, 7oth

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%re"ented in the ne>t "e'tion )!2!26 the num7er of individual" ma# in'rea"e orde'rea"e

5*ig!1:d, *ig!18d, *ig!1d, *ig!20d6!

5././S!ear&o(

In thi" "e'tion are %re"ented the re"ult" o7tained in four different "'enario" 5"ee Ta7le!26, thu"

%ermitting an effi'ient anal#"i" of the &M %arameter"!

3'enario 1 i" an ideal "ituation 4ithout environmental or anthro%ogeni' "tre""e"! When

'om%aring the different "'enario", "'enario 1 i" the referen'e "'enario!

3'enario 2 i" a "ituation 4ith a le"" fertile %o%ulation, 'on"idering a le"" "ignifi'ant num7er of

"%a4ner" %er 'la"" in the adult "tage! Thi" "e'ond "'enario re%re"ent" a "ituation 4here the

fi"h %o%ulation e>%erien'e environmental "tre"" 5other than food availa7ilit# and 4ater

tem%erature, alread# in'luded in the model6, 'on"euentl# de'lining the re%rodu'tion a'tivit#,

therefore 7eing le""fit 5Rail"7a'@ et al, 16!

3'enario $ i" a "ituation 'on"idering anthro%ogeni' "tre""e" 5e!g! fi"hing6 over all the'la""e" of the adult "tage, re%re"ented 7# an in'rea"e in the 'hara'teri"ti' mortalit# 10

time" higher than in the referen'e "'enario!

3'enario ) i" a modifi'ation of "'enario $, 'on"idering fi"hing "tre"" over the adult 'la""e"

e>'e%t for the #oung?of?the?#ear individual" 5to "imulate the re"ult of fi"herie" la4

re"tri'tion in fi"hing me"h "i=e6! In thi" fourth "'enario it i" a""umed that the %re"ent

me"h "i=e limit im%o"ed 7# the la4 i" "o that it for7id" 'at'he" of fi"h in the #oung?of?the?#ear

adult" 'la""!

Although the &M differentiate" individual" in ea'h 'la"" u"ing 7ioma"" value", there i" a

relation"hi% 7et4een the fi"h" 7ioma"" and fi"h" length, hen'e %ermitting to 'om%are thi"

value 4ith the limit im%o"ed 7# the la4! *roe"e &aul# 520006 develo%ed a data7a"e 4ith

a

and b value" of the follo4ing linear

regre""ionJ

# a!)b

5126

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4here # i" the fi"h" 7ioma"" 5g 446 and i" the fi"h" length 5'm total length6!U"ing

&ereda and Killamor 5116 a and b value" 50,001 and $,))8 re"%e'tivel#6 for Engraulis

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encrasicolus, for an adult" 7ioma"" of 10+ mg 52:,) g 446, the 'orre"%ondent total length

i" of 1,) 'm! Thi" length value i" 'on"i"tent 4ith field o7"ervation" 5R, 18-H *roe"e

&aul#, 2000H Dr! .enriue a7ral,pers. com.6!

In the referen'e "'enario 5*ig!1:6, although the %o%ulation "tart" 4ith a "ingle 7at'h, it"

evolution i" uite %rodu'tive G in five #ear" the %o%ulation in'rea"e" from =ero to 1100

adult fi"h 5*ig!21a6! In thi" "'enario the num7er of individual" in the fi"h %o%ulation varie"

a''ording 4ith "ea"onal variation" in food 5*ig!86, %rovided that there i" no other "tre"" to

the

%o%ulation!

a*

%37///7///

,*

$7'//7///

L$ L% L & L'

%/7///7/// $7%//7///

$37///7///

$/7///7///

$7///7///

0//7///

1//7///

37///7///

'//7///

%//7///

/

/ &1/ 4%/ $/0/ $''/ $0//

time (das)

// &1/ 4%/ $/0/ $''/ $0//

time (das)

c*

1///

3///

$ % &d*

1//

3//

O *$ *% *&

'///

&///

'//

&//

%/// %//

$///$//

/

/ &1/ 4%/ $/0/ $''/ $0//

time (das)

/

/ &1/ 4%/ $/0/ $''/ $0//

time (das)

*ig!1: &M re"ult" for the "imulation of 3'enario 1 or referen'e "'enarioS for + #ear" 5da# 0 'orre"%ond" to the7eginning of A%ril6! a6 Num7er of egg" in the fi"h %o%ulationH 76 num7er of fi"h in ea'h 'la"" of the larvae "tageH'6 num7er of fi"h in the 'la""e" of the Buvenile "tageH d6 num7er of individual" in ea'h 'la"" of the adult "tage

5"ee 3e'tion 2!) for more information a7out the"e 'la""e"6!

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When 'on"idering environmental "tre"" 5other than food availa7ilit# and 4ater tem%erature6,

fi"h rea't 7# de'rea"ing their re%rodu'tion a'tivit#, due to 7eing le"" fit 5Rail"7a'@ et

al,

16! Thi" i" the "ituation "imulated in "'enario 2! The 'om%ari"on of "'enario 2 5*ig!186

4ith the referen'e "'enario 5*ig!1:6 %ut" in eviden'e the 'on"euen'e" of a lo4er num7er of

"%a4ner" to the total num7er of fi"h in the %o%ulation! In fa't, after five #ear", the %o%ulation

%re"ent" an in'rea"e of $+0 adult fi"h 5*ig!2176! Therefore, dimini"hing the %er'entage of

"%a4ner" in "'enario 2 to half or higher than that of "'enario 1 5a" "ho4n in Ta7le!26

'au"e"

an evolution in the adult" %o%ulation -) 4ea@er 5almo"t 2/$le""6!

a*%7$//7///

$%/7///,* L$ L%L& L'

$70//7///

$73//7///

$7%//7///

2//7///

1//7///

$//7///

0/7///

1/7///

'/7///

&//7///

/ / &1/ 4%/ $/0/ $''/ $0//

time (das)

%/7///

// &1/ 4%/ $/0/ $''/

$0// time (das)

c*

1//$ % &

d*

1/

O *$ *% *&

3//

3/

'//

'/

&//

&/

%//

%/

$//

$/

/

/ &1/ 4%/ $/0/ $''/ $0//

time (das)

/

/ &1/ 4% / $/0/ $''/ $0//

time (das)

*ig!18 &M re"ult" for the "imulation of 3'enario 2 or le"" fit "'enarioS for + #ear" 5da# 0 'orre"%ond" to the7eginning of A%ril6! a6 Num7er of egg" in the fi" h %o%ulationH 76 num7er of fi"h in ea'h 'la"" of the larvae "tageH'6 num7er of fi"h in the 'la""e" of the Buvenile "tageH d6 num7er of individual" in ea'h 'la"" of the adult "tage5"ee 3e'tion 2!) for more information a7out the"e 'la""e"6!

Regarding "'enario" 1 and 2 5*ig!21a,76, it i" 'learl# identifia7le the 'on"euen'e" of a le""

fit%o%ulation 5"'enario 26 4ith the "ame food availa7ilit# and "ame 4ater tem%eratureJ the

%o%ulation gro4" e>%onentiall# in 7oth "'enario", 7ut more ra%idl# if the %o%ulation i"

more

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fit! Therefore the %er'entage of "%a4ner"S %arameter SEc

i" an im%ortant %arameter in

the

&M model!

If one 'on"ider" anthro%ogeni' "tre"" on the fi"h %o%ulation in the &M model, the re"ult"

are uite different from tho"e %re"ented a7ove, a" it 4ould 7e e>%e'ted! .o4ever thi" i"

an im%ortant "'enario to a""e"" the 'on"i"ten'# of the &M re"ult", "in'e anthro%ogeni'

"tre""e" are an ever?gro4ing realit# in nearl# all real auati' "#"tem"!

In "'enario $, anthro%ogeni' "tre"" i" in'or%orated in the &M model, affe'ting the four

'la""e" of the adult "tage, a" e>%lained a7ove! Thi" i" a "'enario that re%re"ent" the "ituation

of an auati' "#"tem 4here fi"hing a'tivit# ta@e" %la'e 4ith no rule" 5no la4 re"tri'tion6! The'on"euen'e of a higher mortalit# in the adult "tage re"ult" in the dimini"hing of the

num7er of individual" in ea'h 'la"" and after fe4 #ear", in the di"a%%earan'e of the fi"h

%o%ulation

5*ig!16!

a*

$1/7///

,*

07///

L$ L% L& L'

$'/7///

47///

$%/7///

17///

$//7///

37///

0/7///

'7///

1/7///

'/7///

&7///

%7///

%/7///

/ / &1/ 4%/ $/0/ $''/

$0// time (das)

$7///

/

/ &1/ 4%/ $/0/ $''/ $0//

time (das)

c* $ % &

'/

d*

%.'

O *$ *% *&

&3%.$

&/

$.0

%3$.3

%/

$.%

$3

/.2

$/ /.1

3

/.&

/

/ &1/ 4%/ $/0/ $''/ $0//

time (das)

/./

/ &1/ 4%/ $/0/ $''/ $0//

time (das)

*ig!1 &M re"ult" for the "imulation of 3'enario $ or anthro%ogeni' "tre"" "'enario for + #ear" 5da# 0'orre"%ond" to the 7eginning of A%ril6! a6 Num7er of egg" in the fi"h %o%ulationH 76 num7er of fi"h in ea'h 'la""

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of the larvae "tageH '6 num7er of fi"h in the 'la""e" of the Buvenile "tageH d6 num7er of individual" in ea'h 'la""of the adult "tage 5"ee 3e'tion 2!) for more information a7out the"e 'la""e"6!

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When 'hanging thi" third "'enario to 'on"ider fi"herie" la4 re"tri'tion in fi"hing me"h "i=e

G re"ulting in the fourth "'enario ? onl# 7# @ee%ing the #oung?of?the?#ear fi"h mortalit# a"

in the referen'e "'enario, the re"ult" do not lead to the e>tin'tion of the fi"h %o%ulation, 7ut

to a

"tead# %o%ulation 4ith "hort gro4th5*ig!206!

a*

%//7///

$0/7///

$1/7///

$'/7///

$%/7///

$//7///

0/7///

1/7///'/7///

%/7///

/

,*

$/7///

27///

07///

47///

17///

37///

'7///

&7///

%7///

$7///

/

L$ L% L& L'

/ &1/ 4 %/ $/0/ $''/ $0//

time (das)

/ &1/ 4%/ $/0/ $''/ $0//

time (das)

c*$ % &

d*

'3&.3

'/ &./&3

%.3&/

%3%./

%/ $.3

$3 $./

$/

3

/.3

O *$ *% *&

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/ &1/ 4%/ $/0/ $''/ $0//

time (das)

/./

/ &1/ 4%/ $/0/ $''/ $0//

time (das)

*ig!20 &M re"ult" for the "imulation of 3'enario ) or anthro%ogeni' "tre"" 4ith la4 re"tri'tion "'enario, for +#ear" 5da# 0 'orre"%ond" to the 7eginning of A%ril6! a6 Num7er of egg" in the fi"h %o%ulationH 76 num7er of fi"hin ea'h 'la"" of the larvae "tageH '6 num7er of fi"h in the 'la""e" of the Buvenile "tageH d6 num7er of individual"in ea'h 'la"" of the adult "tage 5"ee 3e'tion 2!) for more information a7out the"e 'la""e"6!

om%aring the re"ult" of "'enario" $ and ) %ermit" to evaluate the effe't of the fi"herie" la4

re"tri'tion! (# 'at'hing onl# the fi"h 4ith 1 'm or 7igger ? 4hi'h 7# *roe"e &aul#"

520006 length?4eight relation"hi% i" a fi"h 4ith 2+ g 44 51000 mg6 the fi"h %o%ulation

i" "aved from e>tin'tion 5"ee *ig!21',d6!

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a*$7%//

,*$%/

$7///$//

0// 0/

1// 1/

'// '/

%//

%/

/

/ &1/ 4%/ $/0/ $''/ $0//

time (das)

/

/ &1/ 4%/ $/0/ $''/ $0//

time (das)

c*

d*

'4

1

&

3

'

%

&

%$

$

/

/ &1/ 4% / $/0/ $''/ $0//

time (das)

/

/ &1/ 4%/ $/0/ $''/ $0//

time (das)

*ig!21 &M re"ult" for the total num7er of individual" in the adult "tage, in the fi"h %o%ulationJ a6 "'enario 1, orreferen'e "'enario, 76 "'enario 2 or le"" fitS "'enario, '6 "'enario $ or anthro%ogeni' "tre"" "'enario and d6"'enario ) or anthro%ogeni' "tre"" 4ith la4 re"tri'tion "'enario!

The scope for growth fun'tion determining the variation of the num7er of individual" in the

%o%ulation 5"ee Euation 86 de%end" on the fi"h" individual meta7oli' 'hara'teri"ti'" 5"ee

Euation 6! Although "everal "imulation" 4ere made 4ith different inge"tion, ege"tion, vital

meta7oli"m and a'tive meta7oli"m to te"t the &M model, the one %re"ented here i" theone that 'hara'teri=e" the an'hov#" gro4th! (ut it i" unmi"ta@a7le that if one 'hange" the

meta7oli' rate" then the individual" mean 7ioma"" in ea'h 'la"" 4ould 7e different and

"o 4ould 7e thescope for growth and 'on"euentl# the %o%ulation" gro4th!

In all the "'enario" develo%ed a7ove, "'o%e for gro4th, g, flu'tuate" a" illu"trated in *ig!22

in ea'h 'la"" of ea'h "tage!

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a*

/.$%

gL$ gL% gL&

,*/./%3

g$ g%

/.

/.

/.

/.

/.

/.

/.

/.

/.

/.//

&1/

4%/

$/0/

$''/

$0//

time

(das)

&1/

4%/

$/0/

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$0//

time

(das)

c*

*ig!223'o%eforro4th,

g5d?

16,forea'h'l

a"

"

ofthea6larva

eredinthe"imulation" of

the"'enario"

%re"entedinthi""e'

tion!

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/./$/

/.//3

/.///

$

/

0

/

$

'

'

/

$

0

/

/

ti

m

e

(

d

a

s

)

The

"'enario"

4ere

develo%ed

4ithout

'hanging

the "'o%e

for

gro4th,

"in'e thi"

fun'tion

tran"late"

the

"%e'ie"

meta7oli'

'hara'teri"

ti'" and

environme

ntal

'ondition"

for foodand 4ater

tem%eratur

e, hen'e

%ermitting to anal#"e the

%arameter" of the &M and

not tho"e of

theIM!Th

e'urveof

g

fun'tion

ha" a

mean

valuefor ea'h

'la"" a"

illu"trat

ed 7#

*ig!2$!

The

meanvalue

of g

in'rea"e

" in the

O

and A2

'la""e"of the

adult

"tage

are due

to the

"mall

variatio

n in

the

mean

individ

ual

7ioma"

",

'hara't

eri"ti'

of thi"

life

/.$

/./0

/./1

/./'

/./%

/L$L%L&L'

$%&O

*$

*%

ean

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*ig!2$ Meanfor gro4th'la"" of ea'the life '#'le!

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6-ON-LUSIONS

The re"ult" o7tained 7# the model develo%ed in thi" the"i" are in 'onformit# 4ith field

mea"urement" to 4hat it 'on'ern" 7ioma"" value" of the individual fi"h and gro4thre"%on"e" to 'hange" in the environment 5the IM model evaluated 4ater tem%erature and

food availa7ilit#6!

Re"ult" of the individual gro4th model indi'ate that the gro4th of the euro%ean an'hov#

throughout the four #ear" of the life '#'le 'ulminate" in an adult 7ioma"" of 2:,) g 44

510+ mg6, 4hi'h i" in agreement 4ith field o7"ervation"! Thi" 7ioma"" value

'orre"%ond" to a

1,) 'm length fi"h 5al"o 'on"i"tent 4ith fieldmea"urement"6!

on'erning the IM %arameter", if one 'on"ider" a five time" "maller food amount

5#food6 in the environment 54ith all the re"t of the IM %arameter" remaining the "ame6,

the adult 7ioma"" i" "maller 51:,+ g 446! om%aring thi" re"ult 4ith the fir"t "imulation, it

i" 'on'luded from the IM model that le"" food availa7ilit# 'au"e" lo4er gro4th!

A te"t 4a" made to anal#"e the influen'e of the 4ater tem%erature 5w6! De'rea"ing thi"

%arameter from 18 to 10 , 4ith all the other %arameter" remaining a" in the fir"t "imulation

5Ta7le!16 the model re"ult for the adult 7ioma"" i" of 2$ g 44! om%aring thi" re"ult 4ith

the fir"t "imulation it i" 'on'luded that 4hen the 4ater tem%erature get" 'lo"er to the limit

"u%%orted 7# the euro%ean an'hov#, the fi"h" gro4th i" lo4er!

Al"o the re"ult" of the %o%ulation gro4th model are in agreement 4ith 4hat i" e>%e'ted

in ea'h of the four "'enario" %re"ented in "e'tion )!2!2! In all the "'enario" the %o%ulation

"tart" 4ith a "ingle 7at'h 51+0!000 egg"6 and the egg" mortalit# 4a" 'on"idered 'on"tant and

eual to 0, 5i!e! 10 "urvival6! The mortalit# rate" %la# a 'ru'ial role in the evolution

of the num7er of fi"h in the %o%ulation!

3'enario 1 i" an ideal "ituation 4ithout environmental or anthro%ogeni' "tre""e"! In the

fir"t "'enario there i" a rea"ona7l# %rodu'tive evolution and in five #ear" the %o%ulation

in'rea"e" from =ero to 1100 adult fi"h! 3'enario 2 'on"ider" a le"" "ignifi'ant num7er of"%a4ner" %er 'la"" in the adult "tage 5S

Ec6, re%re"enting a "ituation 4here the fi"h %o%ulation

e>%erien'e environmental "tre"" that de'line" the re%rodu'tion a'tivit#! When

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'on"idering environmental "tre"" fi"h rea't 7# de'rea"ing their re%rodu'tion a'tivit#,

7eing le"" fitH in a five #ear"

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"imulation the %o%ulation %re"ent" an in'rea"e of $+0 adult fi"h! om%aring "'enario" 1 and 2,

it i" 'on'luded that a de'rea"e in the %er'entage of "%a4ner" in the %o%ulation to half or

higher, 'au"e" an evolution in the adult" %o%ulation -) 4ea@er 5almo"t 2/$ le""6!

Therefore, the 'on"euen'e" of a le"" fit %o%ulation are ver# 'learJ the %o%ulation gro4"

e>%onentiall# in 7oth "'enario", 7ut more ra%idl# if the %o%ulation i" more fit! Therefore

the SEc

%arameter i" ver# im%ortant in the &M model!

3'enario $ 'on"ider" the e>i"ten'e of anthro%ogeni' "tre""e" 5e!g! fi"hing6 over all the

'la""e" of the adult "tage, 4ith an in'rea"e in the 'hara'teri"ti' mortalit# 10 time" higher

than in the fir"t "'enario! In thi" "'enario, the re"ult" are uite different from tho"e in "'enario"

1 and 2! A higher mortalit# in the adult "tage re"ult" in the de'lining of the num7er of

individual" in ea'h 'la"" and after fe4 #ear", in the di"a%%earan'e of the fi"h %o%ulation

3'enario ) i" a variation of the third "'enario, 'on"idering fi"hing "tre"" over the adult 'la""e"

e>'e%t for the #oung?of? the?#ear individual" 5to "imulate the re"ult of fi"herie" la4

re"tri'tion in fi"hing me"h "i=e6! In thi" fourth "'enario the re"ult" do not lead to the

e>tin'tion of the fi"h %o%ulation, 7ut to a "tead# %o%ulation 4ith a "mall gro4th! The

'om%ari"on of the re"ult" of "'enario" $ and ) evaluate" the effe't of the fi"herie" la4

re"tri'tion! (# 'at'hing onl# the fi"h 4ith 1 'm or 7igger 54ith 2+ g 44 or more6 the fi"h

%o%ulation i" "aved from e>tin'tion!

The "'o%e for gro4th fun'tion tran"late" the "%e'ie" meta7oli' 'hara'teri"ti'" and re"%on"e"

to environmental 'ondition" for food and 4ater tem%erature! If one 'hange" the meta7oli'

rate" then the individual" mean 7ioma"" in ea'h 'la"" i" different and "o it i" the scope

for growth and 'on"euentl# the %o%ulation" gro4th!

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8 RE-OMMENDATIONS FOR FUTUREWOR9

De"%ite the gro4th of the individual fi"h i" modelled here a" a fun'tion of it" meta7oli'

'hara'teri"ti'" and environmental 'ondition" 4ater tem%erature and food availa7ilit#,the evolution of the %o%ulation gro4th model to in'lude movement rule" a''ording to the fi"h"

environmental %referen'e" i" 'ru'ial to get 'lo"er to the real world! Therefore, the model

develo%ed in thi" the"i" 4ill gain 7# introdu'ing 516 an individual gro4th model de%endent

of a higher num7er of relevant environmental varia7le" and 526 a "%a'e 'on'e%t in the

%o%ulation gro4th model, not onl# 4ith adve'tion?diffu"ion varia7le", 7ut al"o 4ith a "%atial

grid of the fi"h" environmental %referen'e"! In thi" 'a"e, the individual gro4th 4ill 7e

de%endent of the lo'ation of the fi"h in the e"tuar#, "in'e it" fitne"" i" not the "amethroughout the "#"tem! One good e>am%le i" that of the egg"! Egg" are driven 7# the

4ater 'urrent", not 7eing a7le to 'ho"e 4here to "4im! Therefore, de%ending on the 4ater

'urrent" in an e"tuar#, egg" ma# end u% in the "ea 54ith =ero re'ruitment to the %o%ulation

in the e"tuar#6, or in more %rote'ted area" hen'e %ermitting them to "urvive and develo% to the

larvae "tage!

After gathering the @no4ledge of 4hat a" 7een done "o far in the modelling of fi"h

%o%ulation" area it i" in theor# "ome4hat ea"# to %redi't the %ath4a# that thi" model

"hould follo4 in the near future! .o4ever, thi" %ath4a# i" de%endent on em%iri'al @no4ledge

gained in field data %ro'e""ing! *or in"tan'e", to model the fi"h" environmental %referen'e"

it" e""ential to "tud# the fi"h" re"%on"e" to 'hanging environmental varia7le" 5a" "tudied

7# (reit7urg et al, 1H o4an Cr et al, 1H Ca4or"@a et al, 1:H indholm et al,

2001H M'Dermot Ro"e, 2000H Ro"e o4an Cr, 2000H Ro"e et al, 1a, 17H 3e@ine

et al,

11a, 117, 1-, 1:H T#ler Ro"e, 1)6!

In the Tagu" e"tuar# it i" ne'e""ar# to gather the 'om%lete information a7out ea'h "%e'ie"

lo'ation a''ording to the life "tage, "in'e fi"h inha7it different area" of the e"tuar#

de%ending on the "tage of the life '#'le! In fa't, to 7e 'a%a7le to a''om%li"h an effi'ient

management of thi" living re"our'e" in &ortugal, it i" ne'e""ar# an inten"ive "tud# in all

the %ortugue"e e"tuarie" and 'oa"tal =one", "in'e fi"hing a'tivit# i" of "u'h a great

im%ortan'e to the &ortugue"e e'onom#! Therefore, to a "u"taina7le %ra'ti'e of thefi"hing a'tivit#, the %ro'e""ing of field data 4ill %ermit the develo%ment of a more close to

the reality model that in'lude" ea'h "ite 'hara'teri"ti'" and their influen'e on the evolution of the

fi"h %o%ulation"!

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:A-9NOWLEDGMENTS

Im ver# grateful to &rof! 9enneth A! Ro"e 5oa"tal *i"herie" In"titute and De%artment of

O'eanogra%h# and oa"tal 3'ien'e" from the oui"iana 3tate Univer"it#, U3A6 and &rof!Ma"ahi@o 3e@ine 5De%artment of ivil Engineering from the amagu'hi Univer"it#,

Ca%an6 for their e>%erti"e and @no4ledge of the individual?7a"ed modelling and modelling

of fi"h" gro4th a''ording to their %referen'e for environmental 'ondition", re"%e'tivel#!

I 4ould li@e to than@ &rof! Ramiro Neve" for the idea of thi" the"i" initial theme, for hi" good

re'e%tion in the re"ear'h team 5MARETE6 and al"o for the revie4ing of the

final manu"'ri%t! Im grateful to M3'! &edro &ina 5from MARETE6 for the re"ult" of hi"

model and hi" "u%%ort for thi" the"i"!

Al"o of great im%ortan'e 4a" the @no4ledge of &rof! &aul Nival 5a7oratoire dO'anologie

(iologiue et d'ologie du &lan'ton Marin, 3tation oologiue de Killefran'he?3ur?Mer,

*ran'e6, taught during the DEA training %eriod in Killefran'he?3ur?Mer!

*rom the Ne4 Univer"it# of i"7on I 4ould li@e to than@ &rof! CoFo ome" *erreira,

M3'! CoFo &edro Nune" and M3'! Maria Tere"a 3ima" for their "u%%ort and idea" in the

'on'e%tion of the model %re"ented in thi" the"i"!

Im ver# than@ful for Aida Alvera A='arate" "u%%ort and 'om%anion"hi% throughout thi"

the"i", al"o for the revie4ing and im%roving of the final the"i" %re"ented here!

I al"o 4ant to than@ Dr! .enriue a7ral 5O'eanogra%hi' In"titute of the Univer"it# of

i"7on, &ortugal6 for offering hi" time to find field data 'on'erning the euro%ean an'hov#"

e'olog#!

M# "in'ere than@" are al"o to Dr avin (egg 5R Reef Re"ear'h entre of the Came" oo@

Univer"it#, Au"tralia6, &h!D! Came" indholm 5National Under"ea Re"ear'h enter for the

North Atlanti' reat a@e" from the Univer"it# of onne'ti'ut, U3A6, 3teve Rail"7a'@

5ang, Rail"7a'@ A""o'!, alifornia, U3A6, &rof! Ragnar Arna"on 5Univer"it# of

I'eland6, Trevor .utton 5E*A3, U96, Ki'tor 3el#utin and 3erg (erdni@ov 5Ro"tov 3tate

Univer"it#, Ru""ia6 and Anthon# R! Wil7ur 5Ma""a'hu"ett" oa"tal one Management, (o"ton,

U3A6!

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*inall#, 7ut not lea"t, I than@ m# famil# and friend" for their 'ontinuou" "u%%ort during all

thi" DEA at the Univer"it# of iVge,