La pêche au crabe girafe : l'expérience des Seychelles = The ... - IRD
La pêche au crabe girafe : l'expérience des Seychelles = The ... - IRD
La pêche au crabe girafe : l'expérience des Seychelles = The ... - IRD
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2. LA..TECHHIQUE VE FECHE<br />
captufCs avec <strong>des</strong><br />
11 s'aoit d'un<br />
~~ercle de fer d'environ 1 &tre de diaretre<br />
recouvert d'une double nappe de filet<br />
maillant (naille etirte d'environ SC.); 10 P<br />
20 balances sont æontCcs, espacCes de 10 P<br />
20m, sur une filibre principale, <strong>La</strong> balance<br />
est;rappatCe, prefCrentielIemcnt avec de la<br />
bonite fraiche, et IaissCc en peche environ<br />
une quarrntainc de minutes. Le <strong>crabe</strong><br />
<strong>girafe</strong>, chrnivore, vient railler ses pattes<br />
dans le filet sans pouvoir ~'Cchapper. Les<br />
t<strong>au</strong>x de capture peuvent ateindre jusqua& 30<br />
<strong>crabe</strong>s par balance, mais varient en gCnOr.1<br />
entre 1 & 4 <strong>crabe</strong>s par carrelet. ,<br />
Les bate<strong>au</strong>x iæpliquts dans cette peche <strong>au</strong>x<br />
<strong>Seychelles</strong> sont de tailles tr&s variables:<br />
6,. A i4a selon les zones de peche et<br />
utilisent en -moyenne 4 filibres de 15<br />
balances. <strong>La</strong> duree de la rarCe varie entre<br />
1 et 4 ìours et .les <strong>crabe</strong>s sont conservCs<br />
sur grace.<br />
f<br />
3. LES zuws VE PECHE<br />
Le <strong>crabe</strong> <strong>girafe</strong> est un <strong>crabe</strong> fouisseur dont<br />
l'hsbitat est constitu¿ de vastes zones de<br />
sable dont la fraction ffne est importante.<br />
On le trouve surtout dans ¿es fondsde 30 P<br />
50r. En. Australie, (Br<strong>au</strong>n, 1986) il est<br />
signal4 de.0 A 80. de profondeur et B H<strong>au</strong>eii<br />
(YANSANT, i9782 de 2 d 200~. Il sewblerait<br />
qu'<strong>au</strong>x SeychrJJes, il soit present Fur<br />
l'enserb1e du plate<strong>au</strong> 'de Hahe, 18 o& le<br />
substrat est adCquate, nais avec <strong>des</strong><br />
densites parfois tres variables,<br />
4. ETUDES EH COURS ET PREHIERS RESULTATS<br />
<strong>La</strong> section recherche de Ia SFA est<br />
responsable de statistiques de peche<br />
ícaptures, effort en nombre de balances<br />
pos4esJ et a m i s en.place un programme de<br />
bioloaie pour connaitre les caractCristiques<br />
de la population:<br />
Le table<strong>au</strong> 2 donne les rCsultats<br />
preliminaires de cette Ctude et Its compare<br />
A ceux d'Hawaii et d'Australie.<br />
5. LES AUTRES PECHERIES :<br />
LES EXEtfPLES HAWAIEN ET AUSTRALIEH<br />
H<strong>au</strong>eii exploite depuis longteaps le <strong>crabe</strong><br />
<strong>girafe</strong>, les preiiPres statistiques remontent<br />
a 1950, les captures annuelles maximales<br />
s'CICvent A 18,8t en 1968 et 29,Zt en 1972.<br />
3 A 4 bate<strong>au</strong>x sont ConCernCs, a temps<br />
partiel, par cette pecherie. Les <strong>crabe</strong>s<br />
sont conservCs et vendus vivants en viviers<br />
(t<strong>au</strong>x de mortalit4 infCrieur d 5%) B <strong>des</strong><br />
prix de 7 & 10 US$ par kg (prix 1985)- Les<br />
Stocks ne semblent pas surexploites rralgre<br />
une peche rCcr4ative non controllCe tres<br />
importante: Suerdloff (1979) propose un<br />
M.S.Y. de 70t/an.<br />
Les pecherìes <strong>au</strong>straliennes du Queensland et<br />
du Neu South Uales sont be<strong>au</strong>coup plus<br />
rkcntes (1970) et d'envergures PIUS<br />
Boats 'of different sizes are used in this<br />
fishery in <strong>Seychelles</strong>: 6-5 to 14m (with a<br />
catcher boat), depending on the area firhed.<br />
<strong>The</strong> usually use 4 linea of 13 nets. Fiahing<br />
trips last 1 to 4 days, and the crabs are<br />
kept on ice.<br />
III. FISHING<br />
<<br />
<strong>The</strong> Kona crab normally lises buried in thi;<br />
sand, %o that extensive fine sand areas arcs<br />
its h8bitat. In <strong>Seychelles</strong> it is fbund<br />
mainly at depths of 30 to Som, Wtrile in<br />
fiustrrlia the range i5 O to 8Om (Bronn,<br />
1986) and 2 to 200m in Hawaii (Vanunt,<br />
1978). <strong>The</strong> <strong>crabe</strong> seem to exist all over the<br />
nah& plate<strong>au</strong> whære the substrate ir<br />
appropriate, but at varying densities.<br />
IV. [XIRENT RESEARCH AND FSRST RESUtTS<br />
Catch md d+wt (number of hoopnet acts)<br />
are kept by the SFA, which ir also<br />
conducting a biological sampling progrman<br />
in order to determine the population<br />
charactwistlcr. fable 2 gives prclfninary<br />
results, comparad to those obtaained in<br />
Austral i a and Hawai i.<br />
V. THE AUSTRALICHJ AND HMAIICUJ FISHERIES<br />
F.? Stætictical sampling of the Uduriisn fishery<br />
strrtd in 1950. Maximum -annual catches<br />
m œ ' recorded in 1968 (18.8t) and 1972<br />
(29.2tJ. 3 to 4 boats are engaged part time<br />
in t'he +irhuy. <strong>The</strong> crabs are kept alive in<br />
*11a (mortality rate under W.), and sold at<br />
prices ranging from $7 to *lO/kg (1985)Qz<br />
Stocks do not æpptar overexploited <strong>des</strong>pite a<<br />
large warts fishery; Snrrdloff (1979%<br />
suggests an PtSY of 70t/year. , .--<br />
T h Austrrl i en ti aheri es of Queenal and and<br />
New South Maler are more recent (1970) and<br />
much largw, &th annual catches of the<br />
order of SOOt (Bronn, 1986). Pricer range<br />
from USS4 - S/kg. <strong>The</strong> fleet is compared of<br />
6 - 7171 outboard-propelled craft, using<br />
several lines of 20 traps. <strong>The</strong> fishery is<br />
not seasanal and catch rates are high,<br />
averaging 4.3 saleable crabs per net set-<br />
Export of crabs to Hawaii is envisaged at<br />
thi,s time. .<br />
. z<br />
IRecmendati ais - 1 egi 81 ati on and its<br />
results in the 2 cwntries:<br />
CI minimum size l i m i t is applied both in<br />
Hawaii (95", posterior carapace margin to<br />
right æye stalk) and in Australia (100mm).<br />
Versant (1978) suggests a close season for<br />
females during the reproductive period<br />
(summer), rather than limiting fishing<br />
ef f art. In both countries, as in<br />
<strong>Seychelles</strong>, fishing berried females is<br />
prohibited. No attcmpt is made to control<br />
mesh sirca, as trials have demonstrated that<br />
there is little relationship between meaty"<br />
size and the size o+ crabs c<strong>au</strong>ght.<br />
w<br />
Jn Hawaii, the high mortality among crab,<br />
releasee if legs are broken off uhile<br />
unmeshing them (70% mbrtality for one broken<br />
leg - Onizuka, 1972) we5 publicised among<br />
fishermen.<br />
t<br />
u1<br />
Co