A REVIEW OF AVAILABLE BLUEFIN TUNA INFORMATION FOR CHINA:

Transcription

1 SCRS//13 Col. Vol. Sci. Pap. ICCAT, 55(3): 33-1 (3) A REVIEW OF AVAILABLE BLUEFIN TUNA INFORMATION FOR CHINA: DAI Xiaojie 1, ZHAO Liling, XU Liuxiong 1 SUMMARY Infoation is pesented on the bluefin longline fishey fo the peiod in the nothen Atlantic Ocean (5º N~º N, 15º W~3º W). In addition, soe biological infoation fo the obseve poga is povided fo the Mediteanean Sea fo the fishing seasons. Since 199, the Chinese tuna fleet has withdawn fo the Mediteanean Sea and shifted to the nothen Atlantic Ocean. The highest noinal catch ecod was 137 t in 1995 in the Mediteanean Sea with the fishing effot 13 thousand hooks. Thee wee. t noinal catch in 1 in the nothen Atlantic Ocean, with a fishing effot 33 thousand hooks. Noinal CPUE fo 1995 and 199 fishing seasons ae.3 (nu) and (nu) pe thousand hooks espectively. Size data show that aveage fok length in the catch in 1995 and 199 fishing seasons (May and June) exceeded c. RÉSUMÉ Des infoations sont pésentées su la pêcheie palangièe de thon ouge pou la péiode dans l Atlantique nod (5º N~º N, 15º W~3º W). En oute, cetaines infoations biologiques du pogae d obsevateus sont founies pou la e Méditeanée au tite des saisons de pêche Depuis 199, la flottille thonièe chinoise n opèe plus en Méditeanée, s étant déplacée ves l Atlantique nod. En 1995, les captues noinales ont atteint le chiffe ecod de 137 t, avec un effot de pêche de 13 ille haeçons. En 1, les captues noinales se sont élevées à,t dans l Atlantique nod, avec un effot de pêche de 33 ille haeçons. Les CPUE noinales pou les saisons de pêche de 1995 et 199 se situaient à,3 poissons et 1,319 poisson pou ille haeçons espectiveent. Les données de taille indiquent que la longueu à la fouche oyenne des captues éalisées au cous des saisons de pêche de 1995 et 199 (ai et juin) a dépassé c. RESUMEN Se pesenta infoación sobe la pesqueía de palange de atún ojo paa el peíodo 199-1, en el océano Atlántico septentional (5º N-º N; 15º W-3º W). Adeás, se popociona cieta infoación biológica del pogaa de obsevadoes desaollado en el a Mediteáneo paa las tepoadas de pesca de Desde 199, la flota atunea china se ha etiado del Mediteáneo y se ha diigido al Atlántico note. El egisto ás alto de captua noinal ascendió a 137 t en 1995 en el a Mediteáneo, con un esfuezo de pesca de 13 anzuelos. En 1 se egistó una captua noinal de, t en el océano Atlántico septentional, con un esfuezo de pesca de 33 anzuelos. La CPUE noinal paa las tepoadas de pesca de 1995 y 199 fue de.3 (núeo) y 1,319 (núeo) po il anzuelos, espectivaente. Los datos de talla uestan que la longitud edia a hoquilla de la captua de las tepoadas de pesca (ayo y junio) de 1995 y 199 supeaba los c. 1 College Oceanogaphy, Shanghai Fisheies Univesity, 33 Jungong Road, Shanghai, China(P. R.). xjdai@shfu.edu.cn Division Distant Wate Fisheies, bueau Fisheies, Ministy Agicultue, No. 11 Nongzhanaguan nanli, Beijing 13, China(P. R.) 33

2 KEY WORDS Chinese bluefin tuna fishey, catch statistics, fishing effot, size coposition, Atlantic Ocean, Mediteanean Sea 1. INTRODUCTION Since 1993, the Chinese longline fleet gan to opeate in the high seas topical Atlantic ocean tageting bigeye tuna. Afte 1993, thee ae two o thee longlines shifting to Mediteanean Sea tageting bluefin tuna. Afte 1997, Chinese longlines had withdawn fo the fishing gounds Mediteanean Sea and shifted to the Noth Atlantic Ocean. The ain spawning gounds the species in the Mediteanean ae located f the Baleaic Islands and f the Tyhenian coasts (Gacia, et al. 1). Because the Chinese tuna fleet had opeated in these spawning gounds, the epot the Chinese bluefin tuna fishey in these aeas is essential fo easten bluefin tuna stock assessent. The docuent pesents infoation on the Chinese bluefin tuna fishey fo the peiod and also soe biological data by the obseve poga conducted in in the Mediteanean Sea.. MATERIALS AND METHODS The Chinese longline catch and effot data fo bluefin tuna wee used in this study. JIN FENG No. 1 was onitoed by obseve in the 1995 and 199 fishing seasons. Catch and fishing effot ae ecoded in the logbook. Thee ae fou banch lines pe baskets. Squid is used as the ain bait in the longline opeation, but occasionally coon ackeel. Hooks pe set ae aound ~. All the species caught by longline fishing wee ecoded. Length was easued as fok length(fl) fo bluefin tuna, to the lowe 1 c. 3. RESULTS AND DISCUSSION 3.1 Fishing gounds and fishing seasons Fo 199 to 1997, fishing gounds Chinese bluefin tuna ae located at the westen Mediteanean Sea, wates 37 o 5 N~39 o N, o E~1 o E (Figue 1). The fishing seasons anged fo Apil to ealy July. Since 199, fishing gounds fo bluefin tuna shifted to nothen Atlantic Ocean, wates 5 o N~ o N, 15 o W~3 o W. Table 3 shows onthly fishing gounds in and 1. Fishing season geneally anged fo Septe to Febuay. 3. Catch and fishing effot Table shows the noinal catch and fishing effot by Chinese longline fishey tageting bluefin tuna duing 199 and 1. The highest ecod was 137 t (in ound weight) in 1995 in the Mediteanean Sea. Duing ecent two yeas, the total catch by Chinese l;onglines aintained aound 7- t cause China fishing copany stictly coply with the quota set by ICCAT. Fishing effot stabilized aound 3 thousand hooks in and 1. 3

3 3.3 Noinal CPUE by obseve poga The total nu fish caught in the 1995 fishing season (May and June) is 13, and 15 in the 199 fishing season. Noinal CPUE fo 1995 and 199 fishing seasons ae.3(nu) pe thousand hooks and (nu) pe thousand hooks espectively. 3. Dessed weight and size coposition by obseve sapling The aveage dessed weight individual in 1995 and 199 fishing seasons wee listed in Table 1. Aveage dessed weight individual in May was heavie than that in June. Actually, these fish longed to spawning population and a lage nu individual ae conducting spawning in May in the westen Mediteanean Sea accoding to sapling obsevation. Obviously, soe fish had alost copleted spawning pocess in the late June and ealy July. Figues -5 shows onthly dessed weight coposition duing 1995 and 199 fishing seasons. Doinant goups dessed weight in May 1995 wee 1kg-1kg and 1kg-1kg, accounting fo % and 3% sapled catch, espectively. And in June, 1995, thee ae fou doinant goups, 1kg-kg, kg-1kg, 1kg-1kg and 1kg-1kg, accounting fo %, 1%, 15% and 15% sapled catch, espectively. The dessed weight coposition fo 199 fishing season showed siila tend. Doinant goups ae kg-1kg, 1kg-1kg and 1kg-1kg. Figues -9 shows onthly size coposition duing 1995 and 199 fishing seasons. The aveage fok lengths in May and June 1995 wee 19.3 c and 3.7 c, espectively. The doinant size goups in May, 1995 wee 1- c(17.9%), -3 c(19.%), 3- c(1.1%). The doinant size goups in June, 1995 wee 19- c(1.%), -1 c(15.3%), 1- c(.%), -3 c(1.%). The aveage fok lengths in May and June 199, wee 1.1 c and 15. c, espectively. The doinant size goups in May, 199 wee -1 c(15.5%), 1- c(5.9%), -3 c(.1%). The doinant size goups in June, 199 wee -1 c(1.3%), 1- c(15.%), -3 c(1.7%), 3- c(17.%). Soe eseach indicates that the longline fishey fo easten bluefin tuna stock tageted adult fish ostly ove 1 c in fok length (FL) and age can each 1 c in FL (Miya, N. 1993). Ou obsevation shows that the aveage FL exceed the 1 c and consideable pecentage age coposition in catch eached o exceeded age. Unfotunately, no size fequency infoation was obtained with egad to Chinese bluefin tuna fishey in the nothen Atlantic Ocean duing ecent yeas. REFERENCES GARCIA, A., J.M. de la Sena Enst, J.L. López Juado, F. Aleany, E. Rodíguez Main. 1. Bluefin tuna egg and laval suvey in the Baleaic sea June 1. ICCAT, Col. Vol. Sci. Pap., Vol. 5():5-31. MIYABE, N Standadized CPUE Atlantic bluefin tuna in the Easten Atlantic and Mediteanean Sea obtained fo the Japanese longline fishey. ICCAT, Col. Vol. Sci. Pap., Vol. XL(1):

4 Table 1 Infoation fo obseve sapling in boat (JIN FENG No. 1) tageting bluefin tuna in the Meditteanean Sea in 1995 and 199 fishing seasons May June May June Nu set Hooks Total dessed weight Aveage dessed weight 17.5 (1.99) * (5.51) 15.9 (7.) 1.99 (.53) individual(kg) Sex atio(f: M) 7:1 5: :7 9:3 * The nu in backet is Standad Eo(SD) Table Noinal catch and fishing effot deployed by Chinese longline boats tageting bluefin tuna fo 199 to 1 Yea Noinal catch (MT) Fishing effot hooks ing boats Fishing aeas Med. Med. Med. Med. N. Alt. N. Alt. N. Alt. N. Alt. - Obs. Obs Note: 1. Med. stands fo Mediteanean Sea; N. Alt. stands fo nothen Atlantic Ocean. Obs. stands fo obseve poga Table 3. Monthly noinal catch and fishing effot by Chinese bluefin tuna fishey in nothen Atlantic Ocean in and 1 fishing seasons 1 Fishing season Jan. Feb. Sept. Oct. Nov. Dec. Total Catch (MT) Fishing effot (1 hooks) Fishing gounds / / A A A A A Catch (MT) Fishing effot (1 hooks) Fishing gounds B B C C D B A stands fo the fishing gounds 55 ~ N, 5 ~3 W; B stands fo the fishing gounds 5 ~55 N, 5 ~3 W; C stands fo the fishing gounds 55 ~ N, 15 ~ W; D stands fo the fishing gounds 5 ~55 N, ~5 W; 3

5 Figue 1. Fishing gounds Chinese longline fishing in the Mediteanean Sea in 1995 and 199 fishing season N = Body weight in kg Figue. Dessed weight coposition bluefin tuna caught by Chinese longline boat in the Mediteanean Sea in May

6 Nu 3 3 fis N = Body weight in kg Fig. 3 Dessed weight coposition bluefin bluefin tuna caught tuna by caught by Chinese longline boat in the Mediteanean Sea in June, 1995 Nu fis 1 1 N = Body weight in kg Fig. Dessed weight coposition bluefin bluefin tuna caught tuna by caught Chinese by Chinese longline boat in in the the editeanean Sea in Sea May, in 199 May, 199 3

7 Nu 1 fis N = Body weight in kg Fig. 5 Dessed weight coposition bluefin bluefin tuna by tuna Chinese by Chinese longline boat in in the the Mediteanean Sea in Sea June, in 199 June, 199 Nu 1 1 fis N = Fok length in c Fig. Fok length coposition bluefin bluefin tuna caught tuna by caught Chinese by Chinese longline boat in in the the Mediteanean Sea in Sea May, in 1995 May,

8 Nu 3 5 fis N = Fok length in c Fig. 7 Fok length coposition bluefin tuna caught by Chinese longline boat boat in the in Mediteanean the Sea in June, Sea in 1995 June, 1995 Nu 1 1 fis N = Fok length in c Fig. Fok length coposition bluefin tuna caught by Chinese longline boat boat in the in Mediteanean the sea in May, sea in 199 May, 199

9 Nu fis N = Fok length in c Fig. 9 Fok length coposition bluefin tuna caught by Chinese longline boat boat in the in Mediteanean the Sea in June, Sea in 199 June, 199 1