---

INTROD'JCLIOE;
Lt present seasonal ichthyoplankton surveys off tk.e Wt-:st
Aîricc!n i>oi:St are boing mad-3 Sy countries in which F,A.O, jrc.5er:ts for
Fishe:ies devp:lopment are est*blished (Senegal, Sierra Liane, I*rc,ry
toast , Ghuna 2nd Congo-Brazzaville) in order to contributo to tl:c :?-Y-
lxation of thi;i.r fi.shzriGs rip:,r~is~l. S St-ndarü s::~ijjl ing :;;ethgti 1~2 ::
bt:eui rccr;ntly rùcommcnded .by t.h? F.A.O. consultunt, Jr. SL<;r:;;1nn (19$)
to bc :idopted for ichthy-oL1.:Inkton surveys off Vest L?AC~ , in .,rdcr -x
ob-t;,:in a more alequate ss;rip?ing of eggs 2nd Rrv:ie :1,-t dif!'~~rr:y,t sizes 1
.r, :j wo 11 2 s rn,xx comparable re,;Jlti; on '<ho niat~ri~cl tce:llec.kiiijm !;y ti ::
d-iff';-Yrent c:3xntries in the Gulf of Guinea.

---

Il-f t!-.c. 12~~6 in the rc;gion~ bC~tWE?ell biGllrCVi~-.ACCI+3 aIld ~~Ci1%Csi.II.-ii:)i~J;~n.
Pei (:gh6) prusented a general ncc~~tint on the diztribcticn '. raCj ': ii 'UilJ', riC C>
of 3~:rdinelln ‘OP.
- - - - - and Anchox>e,l12 (= E&xsli.s
-.-
guin~enÿisj in. tllc:: tf::>1; ii-
g:.:nt*:l shelf of Ghcna. 1~ pralimirxiry
-3
key for t.te idontifi~eticn of e&gs
2 ml lc.rv::t; of Nest African Clu&eisls (Ilisha africana, Harzngul:~ rouxi,
-. m<
Sardin:;ll:,, aurit;; 9 Sc;rdinel?.ri i;‘bn cn
Ethmslosa
cgA
fi*mb-qizts)
- 2nd !2ngraulids
(~n~riuljl~uinacnsis) has becn given Narchal in 1967. Rocently Do~ly,
Ch;t::ll>"gnat 2nd Concind (1969) published their observations on tlic r:.i;ro-
d:.;ctive cycle of 2. adrit; which includes the q.uzntit:;tive
t.1. i ,y t, y je-i-j7A +, 1'~ :; -.
of the 12rvze in the continentnl shelf of Seneg-,l during 1968 inc;, i.n tiic.
~::t:~rs brtxeen 13 * Blxx, C. Vert Islands and Dakar ~3 founti duri:i< th,:
11 JEAI;;' CEBRCOT1' Cruise made in July of the szme yezr. Thc rexlt:; on iv:&-
thyoplankton, hydrogrsphy 8s we.11 as observations on Tuna obtrin:d in
thi-- 3rea covered by the "JEBX CHARCOT" Cruise xx, giv%;n by ,; ha.7 -:; : ':‘)y: t 9
.>
Conand, Crxnoux 2nd Reber,t (1969).
The objective of this pr:limin::ry report is to prnsr:nt the
qu::ntit-,tive date on larv2e of s?rdinella aurita, S. cba rnd al,::uli..;
- - - - - - -
---.-
guineensis collocted during the ichthyopl~nkton curv,?y:: c-,97 in ii';:;?
-.
off Senegal 2nd Hauritania znd to re:L:lte the quantitative rvsu!-t:, to
the environmental feztures. h mrïre complete picture on the iistri'buti :)y~
'If the larvna in the region .:nd on the reproductivc cycle of tix. sp~oi::~
xi11 be possible after compar inon
I
and discussion of 311 th; d-ltn oo-tz-i-
ned in 1968 anci 1969,
The suthor wishes te t:x;r,ress here hcr -, cknowl cdgn.:?nts to :
- N??o CONAND ("Centre Oceznogrsphique de Dnklir-ThL~l~oyi3")
who bits studied the ichthyorJlankton mstc;ri;Il co..l~.:ctxL in
1968, some of plis r+sults have been diacussed Ln tlio prc-
sent report ;
- îk. CEIMPAGNkT, dir:ctor of the Ccnter and Mr. ESGXZ1VSX1,
Croject Manager, for thc outlining of ichthyoplx&.t»n
progrzmme for 1969 5
- N.T. 3OZLY and Mr, GONZALEZ-SLBERDI, rcspcctively bicI;!gists
of -fiil; C%tx and of tlie F.A.0 ?ro ject, for the Cririoal
discussion of the rosults.

---

-3-
- Mr, CREWIUX, hydrographsr of the Cknter, for thl- h,-d.rogr; ,:bi-
csl duta presented here 5
- ~~rs.BBDIO~, Mr. T.SENZ, 2nd. M&. D.TGURE, technirF.1 :i;oistc,nUs
of the plankton Lais., for the sortinc of the l':rvs,c:. Ltt,.~:.ks
c:olleagues of the Canter,for their help in samplin, :tt s::zo
,The mnteriiil consists of 7 s-ries cf pic-.nkton 3ctlTi~~lCS cc.:II.2c-t2:l
durilïg severnl hydro-plankton Cruises mude in 19i;se
The hydro-plankton progr:rmme for 1969 h-:s 3een bLsicall;i t& ,;~~.x
'1s fer 1968 (Chzmpagnat, Aoely, de Bondy znd Cremoux, 1969) 2nd :Lnclz:~:K :
:?) mon;Ghly csuises covering the continent21 shelf of :;eiïeg.zl IX!
Gzmbio with 5 hydroplankton strtions (over depths of 10920,5G9?O0 m, ~;rx.
nt 79 !i.ileS from the isobnths of IOC m.) fer each of the 9 seztiona
~C~O~S the cozst, p-jus 3 intermcdiate stations (Fig. 1).
3) ,bonthl y cruises 13Ef C. Vert peninsula with 13 h~dr:;i,.i~.î:,--t.c:i?
:jt;;ii*:)ns distribute3 along B se:JJi,mperpendicul~r tothe co:,st, ro*il:llint,
off shore ZOO long, 11.
c) 2 summor cruise off Pi:.urit:nie 2nd !Torthan cozst t-f ~;:-Y.;,,,-.~,; ï
frcr: a:. Blanc, 21°W, and C. Vert, lS@N
Unfortunztsly 'isecnuse :i bre,skdown in the engin of tiic -?/'a
L,-:ISREBT :$ïARO 9 the protgrur;Ime could n'3-t be fulfillsd, the cruis:- ;.rt:,.~;lL;;
made in 1969 h-,s baen specified in T:%ble 1, Mcre dtvtailed ir~f,!r~~.:! ti;:n~q
about, dnte, time 2nd geographic;:l position of e:lch pla cikton :; l,.ti,>n ..P.
in the corresponding interim reports of the Centzr.

---

,.’
:,
g ..,
:
“
. ..& ?
&‘.”

---

- I1-
TABLE I.- BYDRO-PLABKTCJY CRUISES IX 1969
--. -
-.-.--,----
--

--

--..A.

--

-I-
-1-- _-,--
Rorizontal h3uls of 10 minutes were inade in th.e coast3; : t,,-
tiens (St,A, over 10 m depth
and St.33, over 20 m depth ) :ind o-cliqu~!
?ii.,Lll s, ~130 of 10 minutes, ;t deepcr stetions,ueing 45 n c*tb:!(: :;t St,C,
OV6S :jO m depth, 90 m, of table at St.D, over
r" 100 m depti-,,arcd
100 m table at the offshore stations, thc inclina tion of tlk.
cdble baing apsroximately constant of 350 ; bath horizc%nt,a?. :-nd &liqu::
hauls were miLde at a speed Gf 2,5 knots.
T"qo types of net were generally used in the offshur;J stations:
"l'K2" r>ncl
1
"Thons " tho,Jgh
oniy
"PK2" in coastal stations:. The ch:issct-ris-
tics ,3î the nets are as follows : "PK2" a conicI net of s:pproxo 4 m
Zen@, 1 m diameter, width of opening 0,785 1~2, niesh siz,e 500 microns j
the no-t "Thons" having the same characteristics but Seing c,.f.iniiar-coni-
cal in shape.
In the February Cruise a net type "Grand Sck,miù.tf' (GO.S), wi+,!;
sc]%;lro opening of 562 cm2 n,nd mesh size of 1 mm, hnuled :lt a SF,-:ed of
,1 knots w:;s used in the lest stations of thc Cruise (SE cI indi.c:~tion;: i;l
Fig. 2 :,nd Tnbls IV). In thn July Cruise off Hauritania snd Se:legal, t!:-;

---

X2 n-,t was l,?st during the survey, therefore only data c;.iL~ct6ti wi-i7L
the "Thons" net cre gv2ilnbl.e for the SeCOIlti h..lf >f X?i?, ;;t,~tlOilS (S ;B
indiczticn in Table VI),
The quantitative distribution of the l:~:r:c, Sc,r :r',Cyz K!~z~~*
FX2 samples are available fer ezch station (Figs. 3-s) T:r;i :jrJ .;P\\* :>:?:.y ;,.:
these, the matsrisl collected with other types of n?t h;,viny l.j!:,?n us $;i.
Tnly for qualitative nnd bicmztric purposes. As no flowneters w:rc; ~LTTCX.-
. .
l~ble -:t the time of sampling 12-t sea 1-t 1s no-t ~~>s..;i'û1<3 tci !;iii.,~; tl?~:, ex.:c-:;
îmount of Vater filtercd zt, ~;<oh station and by rach ne;; L:~ A, 'X?v ;ri;;.~-
liiss, in order to be ab2.c ts: express comparntively ths uats obt;i:ined in
&sf,stions were only "Thons" snE?ples were 3vzili:'Dle 9 essoys h.,V. b::5ï: lil:>&,i
during the last survey using the Just arrived-flow~laters. Bot!1 nets,
ff;i-‘K2” 2nd f"j7honSll 9 with the flowmeter (TSK taTe) mounteti in the centcr :>Y
thc opening9 were hauled in thr U.SKZ!. wn,y. The sxyerim~nt XL:~ c(.~~ciuctud
in ordr:r to find 3ut the a;>) roximate volume of .tJ-,ter filtîrf:d by bath
nets 3s well ;:s to know whethir their Derfcrmance -i$c;re COiiJPZFdb~Z9 in
s;:ite of the àifferunce in shnpe.
Plowmeter rendinsfor 1:; minutes of oblique hauls (l:'O-9:n) for
bath nets hauled r:t the same st<ztions,were as follows :
NET "PK2"
-.-
NET "THON$"
&!TJ. :70
WatQr filt.* '
Rev, X0
I::itér filt,
(rn.3)
I
b-v3>
It crin be seen that thore are not any signific;:tive L!ii‘ferX:l,occ:
in t:l'e ::nount of Ira-ter filtered by both nets at sine-ult;>nf,?ous st;.&:,ns.

---

General mean .OO..OO 469 m3
I-e.---------

---

In the Labcrntory, cl1 fish larvle bave beun sc:rts;A 12-3~; tI1.z
rzst aof the pl?nktonic organisms. The SzArdineliu ,ind En5~r;u.Jid:;e 1 n7r'lci
I , d.i
-.
wir:: determined by spacics 2nd counted 9 meûsurercents 2-t :-izz in-i:c:rv::il ;,Z
1 mm9 have been done only for the Sardinella species.
Identification of Engr?ulis guineensis larvse wa3 dcne c,ccordi;ld
t- the description of Marcha1 (196,:). Differenciaticn betw2en larv,ae df
s. ::iu~rita 2nd S 0
- - - -
& at differant stages wzs carried out a:cor:lin:r i.c 2:;:;
descriptions 5y F-ige (1920) and D'lrlncona (1936-1951) for Jje zurita ::nd t %
ths identification key of F:archsl (1966) ; unpublished drasing by B?:iche
F!S wel? as persona1 biometric Gbservntions, to be prasenteri in t; later
re n::rt
helped in the identification task.
Al1 fish larvas of ~I:F: 1969 Februory cruisv bave heen :n i;.iz,>,l
by 1:~. CON.AND, the quthor bas reviewed the Clupeids m:; teri,:l. in ardu tc
me;:sur? tf-i-3 ~~~FEE: ;-!nd includetl the results in the pr :ocnt rL:l.:,:rt.
:i. Cruises
I--I_ ovor the continestal shslf of Senega’i
pnd. _ .
..lC~iIlbii;
The quantitative distrib-ution of the 3 species as observsd
in the diLferant nonths of the y.?r;r,is shown in Figo 2 (Februarcy)Y
Fig. 3 (Rpril.), iig. 4 (May), Fig. 5 (Bug-September) ,and Fig. 6 (OG-
tober). In ench figure the stations occupiod as well .:s thc; XP~ ic
isothermes :nd the iaobaths are shown.
found
BO I.:,rvae of 2. eb have been/in the Pe'bruary C~G~X; (?igO?)i
wh :‘ 2-l surface isc thermes show vtyry iow tX3mperature v:.1_ucs9 2“ r' -*+
'E-t- ~~~'~
i ,, î.r.>r.
16OC in the qroximity of the CC:JSt to 20°C offshnrr:, ,tI!e s‘:yy 1.7._/ / . .
,_ ,:: li-
nity being highe r than 3594 ,go :Lt cvcry station (Zin. 3'j,42 :r. -
IV;ax. 35,80 $0). Larv=e of 2. aurit :nJ E. ainranoi.8 h,lvn b::r,;.* ?.-~~:::_i
syorndically in some of the st:: tiens 1 occited in regions b:l 1.h ,..u_r.'. .z'.
tcznperctures higher thon 17OC, t?l..is number being -!îl-:T~‘.:~-t~l<.?l :., - _
j i. 1. 1
poor (Table IV).

---

---

i
:
“,
I
.
:

---

”
.
_,,.
.
.f;
‘,?.y
‘. :
,: ?
- :7
2,.
:’

---

---

---

In &Ml thermie conditions, as indi7:;ted by th5 ~rf:~c.~
i :;-
th.;sms nf Fig. J9 gradually increzsed clong the r;outh-srn c Tl 1 5: t f 1 7; .a, $:Oc
\\
0.fF ce Vert to 23OC off C. Roxo, cold upwelling water bzin;; Fi ti i 1 )-l?'<. .. :;. :Il;
only off the nortlz.ern coest. Tlie szlinity of thci wüter did il' -t ir:' Y!:,
I;;uch from the prrvious cr:li.se? in 211 the stations the ;c: iinity v:-+1z::xs
bi:i.ni; higher th2n 3595 do (En. 35?73 :o - Na.x, 35,94 :o), ,', ,c: 2 b s t; "TTC; 6. i ~1
thc? ~revious Cruisie, no finding of 7. eba iarvze rg2s registr:rc-ci ,yit'l &(-a
-
-
exc~:;>f,i.cn of 3 fex s-ocimens c::ptured in the mor2 southrrn .~nd <: i';',z;h,:.pp
stations ; <?. ziurita, larvae were found in small. numbcr cLnb in tb '.' L'Y+~--
h>rc- stations witk; SUTf.?iC6? temr:~rnturc3s highnr thnn l?OC e 3~ .':~.IG,:: c:?
E. uuineensis 1r:rvee was quite sporc:dicdl
-
-
2nd of very Icw qlW~:.~~titrti.v+:
value.
In &y (Fig. 4) when theu&iti;r teli,>erzturr ~7 .i-Le f‘c.gi::.n i:,~:r,:. ;.-
SOfl to 200 - 2jQC In the northc,rn CO::S t nrd to 23') - 26QC :;n tlîe s::LIt!Crn
c~:-.st (Fig. 4) 1Lnrva.e of L. surit3 wer-! quitr? ubundint being Intors ~IX-
q-.:<:ntl.y distributed in station:: with surface ternperztures higher tl;;rn
22.5OC. Szlinity VTI~LES regist,c:red during the cruise were ilicher th:sn
.i
35,6 %2 (Lin. 35964 - I8ax. 36,31 ,<o). The high numbor of 1::rv.e f'cund,O)@ f
:-.s th,nir size r~znges, (Figs. 72,13) indicate clearly tkat -thc> splwni.nE;
c-f t2:- sp<+cioà t?ok pince during this season. 2.
nnd E, ,@neensis
w _----
wer~ practically absact in the collections of Maye
In t.he October Crui:>c: (Fig. 6) Isrvue of thé 3 ..~tx.:~.e L
s:i:?cies h::ve been found along the whole exnlorcd const, thllu& 3. ::uri G::
- -.-,
.o...
/ **..a

---

_iiu ; : c: .t E1 y> ï;ist Srûquently 2nd :rbun.~:,n-$l y Ais-tribut&. Tho si;;'? r:-~,:i,g:
L f il c
l.;:^Vr;Z
of bath SvrdinF?ln si-ecies in&ic,ates that e~:~-!irning of ca. c:urbi zp~ y:-i3
-
bcicj;ii-ming flïoY1g th.e ->:l- Cl@ CO jst anil tl?,at the spzwning ->f S. kbz lg::zj .;till.
-
-
g;--infi; qn, but c;nly oif the uouthern crast wherr the higher tempr:rzturi *:rxi
1 ;)',hJc;I salinity values were registered. Stcitions with S. eb,, l';rv:~e ~reszn-
-
-
t,>::. ,.'..,IE3 ce salinity values ranging frcm 3@,22 ,$o to 32,03 .$, and ~ere Y.:;-
cc1 Lr:(L :!t surface tempernture highcr than 28OC, while S. aurita ixrvec were
mer' frsquently found in tha corthern cool-r stations, TE?<, F:i&;::t number
-f
Id& :::rme of 6. eineensis was collectsd during the Gctobei' :x~~v~~y wh,'n
he:;vy c,oncentrztions were found in the northern region.
3. “Radinle prolongée" off C, Vert
The :‘~a covered by the cruise off C. Vert : nd +he Ioo*:ti.cri -f
t.1: c-. I-yd ï-0 !' i.anki,on stations 9s wnll as surf::ce temper7tures ~:XX~ 57'I.initi(l..:
:I r 6.. ;;h:jXl in Fig. 7. Gnly 3 Cruises were made in 1969 (A-?rii 9 C,o L:>b- ri -.Y$.
Lkmcbt-ir). The dbserved distriktution of izrvae is shown in Fig. 7 ::rtd
F:i-;lc v.
During the Cruises of Bpril and December, Jnly S. :;urita larva:-:
- -m..-
we-ne c9llqcted in tlîn cocistal. atzcions cff V. Vqr-t g while d~rin,~ tti
Oc-r.;jb;;r Cruise ï:rvae of both Z;! r.linellci spacies w6re pra; :nt in :.?rie i.11
if ]i '-l statii:ns xcupied., as ohserved in the Cruise !:;nMe in the s'~m,: ImogtL,
over the continental shelf of Senegai.

---

..j
e

---

I.
r

---

,._^_
._^ “..”
-..,_
l._l&_.
._--
“.
._-._-

”
‘C
._ ,,_.,
..“”
.
.,.
-
-..

-
.,..
.--

-
--.,-
““,.,I-xs-l_-e

_.-
------Y
,_.
_ rl .,. _-__.
^~
__,._
.I
..___-
..,. _-.
. _-.-.
-“I
_--..--,
- ..-..
.
I
-.-”
.
._--.

---

s,,u-thwnrds until 17ON. In thé: samplcs collected ic thi3 i~armir ~.r?titL:.rn
Wilt:?r Off Seneg~?l 9
only the lrrv,:e of 2, + have been s;ar:i;;!.od.
;y?is indiczte;3 8 nor+hwards mi:,ver:ient of the s?awning :~~-~ll-'?i;i~:r, :of
2. *lurit,? at the time that the water is warming UP off th? senrgnlesE:
shelf. The sxne phenomendn WRR observed in July-August 1968 (Boely,
C ha mp 2 gnz t 2nd Conad) 1969) during the "JEAN CHARCOT" survîy in thc
ssme arec~.
In spite of the lick of a montly c?ntinui-ty in the 1969
collections, the pl,;nkton szmpling wrzs scztterxl over the tli..Fferent Lac,c?,x-
n:,graphical s9*sansp described by Rossignol (19155) t
1:, -- Season of cons-ta1 upweli&~, fri>m Januzry to &:~y, ch;r ::z-
----<--.. -~
t?ri.zed by vsxy low tempernture, j6°-240C and high s2linities, 35?3-36,O -b.
3 - Wxm 2nd cslm sezson,
July-August-Septcmber, with ~2 n,,r.zi-
MUR nxming up af' the water, Temp. 260-29oc, and salinity still highvr
t‘hr,n 35 .io in J;zly, but decrensing from Pdly to DE;cei=1Jer.
c - Tr,,nsitiorxl season, from the end of Septembc.r t.:: 3:i~:-:~~b :r
- -
rshen the wzrm dessalinated wntas are replaceci by cold wnter of high
s:ilinity
CoI:lp?ri.ng thc quLntitc:tive distribution of the Zlujeids ?,;Y,-:?.-
with ths seqsc:nal oc:eanogr^phical regimo off Senegnl 9 it vay:! be cancluded
t11:: t :
place
a) n? massive spawning tnkes /during the cold upwelling se? soc
f:!r both Sardinella specips, :s observed in the Crui;ies of k"ebru:trj .:- y1 ij
-
April ;
b) the massive.spawning of 2. aurita 32s rogi;jtiir-d during thü
when
ti-so tr2nsitior:al seasons : in Msg/the wnt,ers star-& Kr2ILrI‘i~ up :I?f tlla Si'Y;ci!-
gnlc;se cocist 2nd in October, when the waters (of tha wzrm se-iS,:>n ilr(:
rc?plzced by çclder waters of higher salinity ;
c) the massive spnwning of S
eba,
-...* - August-&n tc::;.ber " .-, ,'\\ II <-
.I' L.1. rr., ,'.,
t::ke plsace :;nly during the warm sonson 2nd zfter the decrc;asing :If tbi:
solinity 3
..00* / aaoao

---

- 12 -
d) 3-t the beginning of th'z warm sezson off t3:e a..neg,?J.eso csse-t,
tb2 s~a~~ning pcpulation ':f Se aurit seems t9 n3Ve ilC??thWil?dS, ii:i~~el12Gi
by the front of warc: water.
TEPPER'TKRE ANI) SALIKITY RELATIONS
Berrit (1961) distinguished for the surface layers cf the Gulf
2f "Juinen, feur catcgoriss of waters, defined by the isotherm of 2&,.OC
2nd the isohaline of 35 $0 z
A- "Warm water of ic,w salinity" t>24oc
s-.1 . cg 35 j30
-0 - "Warm water of high salinity"t>23OC
S:;l.
:
> 35 SC
c - "'Cold water of hiqh salinit3fft<240C
521 . > 35 $2
3- lVC~ld water of low salinity" t<240C
C?::l. < 35 ,$c
0nJ.y the thre e first n~:rned water musses ha-ve besn :fsund .)vor
th? continental shelf of knsgal nt diîfarent seasons of th,; y'-;;>.
In order to define th.r? physicochemicnl chtracturistics o.f tl:+..
Y2 tc r and its ralatia> with Clupc:ids larvae as obJerved in 1;3@i, thc
;:lccurrence of S, aurite and S. eba wns plotted agcinst the t~~mperafure
-
-
.:nd sslinity o&* thc surface 1 :yer found in the diii'rrent plnnkton
Cruises of 1:16'j (Figs. 10 and l-t),
The tvq~erature .and salinities plotted correspondwith surf?cc:.
v:;lue 2s no d:ita for tac st::tnd:.rd depth of 10 n were avail :Ibl.e fur -11.1
the plvnkton stations, which would hr.vc been cerkinïy riiore re!~~rou~:vlt::-
tive ;s not S:;I much affactzd by diurnal and local :;KKJiX31i.~S.

---

---

.---. ., _. ._. ..^_-.
.I__..,_.I_...
“-.----” --r.-
<^.,..
II
._...<
I_
,..
r.
f$ >g.:

---

- 13 -
1. ow ::a~ntitative value y the Very few SpeciCleIlS of 2. ?ba (Ti t . 12) Xrrc:
caught in Irater warmer than 23OC and measured bstween le anci
23 mm in standard length.
T%e temperature (20° to 26OC) and salinity (35,6 ;co to 3"*s8 3~)
vzz.iues of the stations occupied during the Kay Cruise (Pi,. 10, V) :.!sK
th(cpresence along the Senegalëuse toast of *%armer water of !:igh sali-
ni-t? ; larvae of 5. aurita have been capkred in most of the stations
anii in great numbe=V).
The widest rang-s ùf' t~~mperature and saiinity have bcen found
during the Jul;- Cruise (Fig. 119A) which extended beycnd the northsrn
limit of the WDI’ITI water masses. The stations located in th(: more n~r-
thern area werç still in "cold water cf igh salinity", whil.e the suuthern
stations reached the "warm desu!inated water" masses. During tki,~ cruise
larvae of s6 aurita were
-
-
found in grzat abrfndançe and associa: :d :;itii t5,-
ccld water of hi& salinity, extc$nding southwardsaiso in ~,rmer -lators, but
always at salinity values higher tlran 35s5 -%o,
,
On the other h,;na, lar.vhc
of s. eba prere
-
-
alzsociatod with ,Grat,nr of higher temper;ture @B~?~~OF).
The as,:;ociation of 2. -
eba with water masies def'ined ‘i::ji Berrit
as "wsrm ~a-ier of 110~ salinity" is still more evident from d21;a of the
*zri; i s? made in August-Zep-tsmb~~r (Fig. 11,S) rrhere morjt of t.ho positive
sta tiens are at temperature higher than 27OC and saiinity values io1:T'er
than 3590 (0.
In Jctober (Fig. lC,D) when the sea temper:Ature i,; still ?,igh
( ~4~2) and th,? snlinity ranges are quite wide ( 30 $0 to 3,s :b) l:,r-r3e
of both species of Sardine112 have been found s Sardinel;a eba l;:rvae
wer r? ,:iir:tri Buted main:1 y at stations of low salinity (<35 <o) :id. 2e aurita
mainl;f 3-t stations with lower t:,rrrp?ratures k 27OC).
Before considering the aize composition of tho :a.~:~ 1 j;c;;;, ; ::-.
tion it is nece~sar'y to mention that Our ddta bave some ii,;:Li; '.i.., 1'
tnainly due to ti;e Frobïem prcaented by the sampling of larv,:r,.

---

- 14 -
Ahlstrom (1354) pointed out the diffic-dlty ?iu~: t.2 net s.%lecti-
vity :?nd t3st4d the xriy to detrr!:iine, though san?ling with gc~rs of
diff:?r-nt nesh sixes ,the pr)>portion of Yarvne of et:ch size c:;tl?gorics
USUZI: y rst:.ined 'c y the strzndL,rd gex used. Thv sa3LLer 1:;rve.i: ère not
fui!y szl:lFied ?)y rlet cf regular siee meshes as they escal>e îrom the
Ill'3 A.3 s , Cn the othcr h?nd it w?s proved th,st the l:rgr?r Sardine i~rv:~~:
;:r:: undersam~lc:d during the dsylight hours as they clvvid tho nG?t. I,s
our ri:, terial wc1s cc,llocted -with nrts of hi single mesh siz2 (500 microns)
and ::t night '7s well GIS at day time, it must be assumed that a great
propc)rti:>n of small l;:rvac: hi-s esc.apXi 2nd thlt the bigc;er lxrv:i;,; ère
und<rsampled in daylight hauls.
The minimum catrgvry A.ee found in our cateritl :?;:r thfn 1erv::c
cl? b!.th S:~rdincll~ s,lecies, was cf 3-4 mm in stc-.nd::rd 12ngTh, but this
sirJc'
L1
2 w:s observed in quito a iimited number cf strtions, b+-ing the size
range of 4-5 rnc' the minimum usu~lly sampled. The biggest l;xv:a :.,-;zaurxl
fron 23-24 mm9 but thrir number wzs SO mal1 th2-t ihzy nov-.r rcc::t::d
even the 1 ;! of the whole pJpul:rtion sLirn$ed ut the E;L~F~ 3-t. tien.
The size composition ,;f tk;e l;,rv;:e s3rr:slr:d nnd mf:;isuï5i .;t
x:c:h st::ticn h:s been grouped by ':rsn and presented in Fig. 12 (:~!:rt_i?ern
cijc:st vf 3eneg& 7 Fig. 13 (%uthcrn ccxst of_Seneg,;l\\ r.;i~L FiGo 14 (froc!
C. 91...lnc t\\> 1: 0 Vert) . Bhen l-irv:,c of bath soeciee I::I.v~ bc:cn c:aI’iei:ct:+!I
during ;:1 silmt: cruiseS their sizc? c:-,mpcsiti.cjn is gsncxLiiy
i uit; ,jif"i->-
rcnt : (sec, Figo 1.3 April, scuthern :Irc;a and Fig. 12 Octobhr, northxn
IlSF3 >, as cari be supposed knuaillg th::t the rsnr:iActivo De?l*iL,lc. i‘cr b:;th
species in thc same geogr;:phiczl are:lg is different.

---

.
..“.

‘
_
‘
,_
, _
.
-
.
.”
.
.
..-

_
I ”

_ I . ‘ _ , j l .

.
.

. . / . . . . . _ . . . . . .
. -

_ .
. _ .

---

. . ,.:

---

c.2n:nosition f3r S. surita ::s jbt;ined in February o off the coJ.iler ,s~;u-
- --
tbern cozst the few IZrViiF: founù Were longer th::n 16 mm, w!;iZe in ;Us:
wzrmer wster 3ff the northern co:,st 3 si.ze groups 3re pr6seztg onc :If
which is rnsde up by iarvne of snmll size (4-8 mm), Cn the othvr h,,nd
3. l?b:: shows the CE*S~
-. -
inverse during Bugust-Septekber : the hi;;;hcr ij,>r-
cent r?f l.xvn? capturrd in the southern area wns representsd by size
rance of 7-8 .nm, while in ths northern area the higher pnrc;:nt is givez
by lzrvae of the sc:zller size (4-5 mm). In October, an tbc oantrqr,y,
l:irv:~e cf c;. 5& at internodiV,.te
size (13-14 mm) cire found in the LXX-
thern regicn where the temper:"ture were lower than 25OC, while in Lhe
sr,uthurn region9 with tcmpaxtures still higher than 27?5OC, tke hithest
psrcent was r:?presented by lzrvae of small size (G-7 m). Ishst rf -t;ilc
1,irvae 3f 2. -
t?ba werc ccnfined to the southern region (Tabla II).
T:IBLE,II.-
Total number of lr:.rvae ccll::ctsd by the Af!'-.r5,u-t
196? Cruiscs off the northern :~nd .:;-.trthr:rn ,:i,J::st
of Seneg.:il (Dota from 10 minutes Ix~1 with E:>t
"PK2).
:
t
4
I
:
0
:
S e nurita
:
s. .‘
c>b II
:'
:
E. ~uinxnsis
I
-
:
:
:
:
f
:
:
Nmtlh
South
:
North
Sou-th
:
krth
South
o
:
t
0
0
t
_------------- ---------------------------------------------------------
fi
:
:
:
:
-2
:
:
0
:
t
Fcb.
: 374
156
1
0
0
: 149
22
:
:
Apr.
:
?o
150 8
9 10
t 6
24
:
:
Na y
: 339 1727 : 10
:
12
2
I
t
SGD-t*
:
0
72
:
1439
1999
:
@
:
:
oct.
:
1630
2045
:
5
235
0 100
:

---

---

- 17 -
As no exnerimental work hors been dono on th,? 13J?VI:1 d~V:~lO~j~i~:?t
c..f ti:t, -i;ést
dfrisan Sardinella spccies and as the survey datF. in ;sizc:
cl,:a~;~r:r,iti:,n aro still toomuch limitedg it ,is not possible to detczmix
th.,: ',g: of the lervae capturod in !lur samp'les. Reverthlessg 7 rough i!l3:!
c-n be obt;:ineil if considering thg dat:: estimcted for othsr : rean.
Ahls-trorrr (1(3’j4:! ,javv thr: eutimztiG,n c>f groxth for the north rb':cific
S: : PLI~ r.xi (Sardinop8 caerulea). Ibis species develops(A~llstrol,!, 1953) ut
r.1 : : .n s 5 2 tomp39ture of 14y50 - 159990C, during the m:;jcr :sy>r-wning
p 3 ri,yd , and ,of 18,lOC in the l:!te :spawning period. An av~ir.:~;i. durnt~i:~;n
of 3 y 5 d::.p was ~+stim;:ted for the yolk-sac stage and ,:l sizc: of 495 tc
K
, .:ci.
f r> r t j-! :s
:.srve
i,hat h:::s i:om;)i.i:ted th:is stage .The sarlina larva
&QU~J rc;q-dirs? acc:Tr'?irq Ahlatr~~~:J (1974) batween 1 t.d 2 rxnths to ~IVS-
lop to 24 mm* en,ngth, The ~~Av~o!JI;~+?xI~ ~1' tbe hrva c>f t$e 2fric;+n
fvid.z. I-
.A ,.
ca me' n>ll:.: s-ecLGs,
shcauld be shortor becnuse of the higher tcmporaturr.
r>f its habitat, particularly for 2. eba. The smallest larv;e found in
our saxples, 1::~s than 4 mm in
9 have already c.::~;lple tx?. th3 yolk-
s 3 c s t C!. gn .

---

- i8 -
:
t
:
:
:
:
:
t
:
:
t
:
So~urita :
S.eba : Clw~eid~:: e : 2 o -:uin,:ensis y
>
:
:
: NJ0 of
: ----- ------: ------------: ----- - -----: -----_-------~
:Yzz.rs:Month :S~mples:Totnl: Z"/ :Total t No/ :
?%a1
:Tvt21 :
Y* // z
%
:
t
D
jy* 'D hr:ul:
IL'* 0 haul:
s
NO :
11, ul I
: _____t
-__-_-
g-------;
-----
;~ -----
t ---a--
:-.----g
---------I--~-1-1--~------:
t
:
a
I
:
0
:
:
:
:
8
-,-
In Fig. 15 the average n:onthly number of I.orvc:~ F::T h.!ul is
gr;:phcc'i. in lo;irithmic scale. Only tho lcrvhe of S, aurita :~nd S, eh;1
-
-
rr;~ch-:d V;~~U~S higher than 10 s~ecimeno per h::ul 9 whilc thu ..I~I'v;~~ ;,f
'+Jere i:lWnys very xarce and did not ::XC ed t!:,, aezn v..luo
even in the months of .th&ir grcstcst ;~Y~und;:lcc
. Due to the small numbcr of !:ir:r:;le FIS wt2.1
-
I. p
3 bs the luck OÎ si.20 measuraclent it is not yet gcssible -t;! ,~y whc:t>or
the 3 aeaks ,3f z6 Lwineensis nr? r?i:,ted to spawning gcrioQ
.
.
.
.
‘20*0
/

---

---

In Figo 17 is plottc;d ths monthly percsntual nbund;ncc :f sa
:;urita
,.:nd S. eba Larvac in relsti.?n to the total l.:rvee cji' elu~)ei~is
-
-
-
-
,-;i)t-.inç-d monthly
sver a year ?jel~iod. 2. aurita larvye renrc:scntk?d zho
highast percent of tfle Clunc-,ids larvae during :nost af tho :;,intk,iy crl,ia<;q
with the exce,!tion ;-:f ,Tuly9 .iugust ,..nd September when 2. .;bn J.arvao wore
the m:>st ::bun..lant, Beverthlcss tho siee compoA tion :3f th:; 1.::rv:l p:.,,u-
1 ::ti3n of S :iuri ta 2s weli as th2ir numarical ::bund:lnce
' T, .
--
&>C;l~ h<2-,u.l (1: 1s.
15) shows th:+: its m:!ssivo sp*;wning tskss plu ce i:ver two 3.i:finite I:+::raic:s.
In Fig. ? 6 sre shown thc: rnonthly nvernge s-,l.rfzca IXKQIELY XU;;..~
ïtgist r,;d a-t c? fixeti station luring 1968 ond 1969 (drrtc! frc-rn _FiLydrcgrz-
phiCa1 .Lab. of the Conter). R comparison between tha distribution :If th?
J.*:rv-.o of b;th &rdineLln speoies (Fig. 15) ZII~ the :r:onthly ~LV~~FI~C? tsin-
7)~‘r:: ijuras
2
(Fig. 16) shows a f-?irl,y gaod corr+lnti.en E: the highest c~no~n-
ti7tivn 3f 3. $32, ï! ~V:a9 c;in-:ide with thc2 warmest waters while th:: tw\\J
penks fer S. curita lnrva îr?
- _II_
rogistered immeGz:te?y befi:se cnd :it:r,
when a graduaIl incrf:asing and ,dscreasing of tht: se': -terrpc, cc! tu-e is t::yking
Il 1 a c e .

---

.
.
2:
.-
.._
.-
J.
.A
.
-I
.I
_
:”
.I

---

‘?
5 cruiscs 3ver the czïitifl5nt2i shelf of Sf2negs.l -.rti G,?.r:2i.T, 9
>
with Tbrut 45 hydrclplankton stati:;ns each &
b) 3 Long sections off. C. Vert u:ntil 20 long. W, with 1.3
hydrs~lnnkt~n static,ns each ;
Two type of nets w9re gzneruly usetl : "PK2" conica.1 r,nJ. l'Thrnsi'
cylïnt..sr-conicr*l y bath with an cjpening itizlcter of 1 m, a lx@hl~f :i:j;:l*c
1. xi 7 land mesh sizv .3f 500 micr.lns.
At sch :2t:lti:)ng c,ne cf Lit~ tw,.; n:-,ts
( lqq-2” in staticns A and B) or b?th (Sts. C, D nnti E) werc hzui.?d during
10 sinutes,
in surfscs at co;;st:>l Stations (over 10 CI :.nd 21) n. dEnth)
r:d nkiliquely -,t dceper stati8>ns, with 45 m of czble ovyr 56 II: d-::,th
(St. c), 90 m aver 100 m depth (St. D) ancl 100 m for t!.e deípor ,Jffsharr:
sts.< ?A.cns *
Th-: luantitntive dir;trir);.rti;>n of each qesi: s exnr:..:; :.: ;.s
nO/lGC n3 of watx filt~~re:d, hr,e hsen s?:own for e::ch cruise in thc ~:AI'K~-
p-ynding ranps 9 in which thc; surf*lcc; ioothcrms werv nl: <) rc1).rc,se!l t,<.:t:l.

---

- 21 -

---

- 22 -
b) 3 rrdi;iies ~r~lclngLc:s à 1.3 1;ztitude du Cap Vert jusqc'it Li>*
?:!ngitude Ouest9 avec 13 steti:;ns d'ichthyoplancton c!~,acunu
c) '1 mission 3' 6té ,3ur i 5 pïrttsau continental de i.laurit~3ni.e :.t
du &ord SSnegal, du Cap Vrrt au C:;p Bl,.:nc 9 comprenant 4 5 9 ta ti.: ns r%t
~e:xécutée à bord <iu "TRUX JR", navire ,XC I'EnqGte Ggionnle.
Aux 2 stations c8tiSre.: (A et B, prof ,n ciour d:l filni 10 et 2C L)
un trait de 10' Gt:iit effectué on surface a '1 ' ui30 du Pli2 0 L-ux :;trti::;n(-j
C, D et E (profondeur du fond 50, 100, ‘jOO m> des trai%s'obIiques C;c>
:'J'
(avec 45 X1 $e câble pour la sta.tion C, 90 m ~)our la station jj9 Adci m pour
La station E), étaient effectués ‘t l.':ide des 2 filets.

---

- 23 -

---

Les tsi.l:toa des larve:: (longueur standard) sont com-.rises ,lntre
le:: intervalles de 3-4 mm minimum et de 23-24 mm maxii:,um. I:or:squc l.e:;
1. ,jrVE, 5 Taos 2 espècf?- etaient reiuîillies au cours d'une mF;me xission,
l%:ur ,G.stribution de taille n'e%ient pas 1~:s mêmes.
ü 0 .ci -t-septembre) ;
b) la ponte de S. aurita precède (mai- juin) et mit IKir.2 ii;- -t, 1-
mont <après (octobre-novembre) crile de 2. eba

---

- 25 -
AL-ILSTRO?4 E.H
‘y*33
- Distribution and abunciance of egs of the Fazific Zardinc
1752-1~256. U.S Fish and Wildlife Service. ï?i.sh 13,uI!.
165, Vol,
GO,PP.
112,5-2?3

---

J’ sijCijl;h F*
193649y
- Clupeic?.a!7 in Uova larve e c;tadi giovanili 2i leïeostéi.
Fauna E Flora dc:.L Golfo di Napoli. Vol* 1 p Jcnog. 3i3.

---

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---