Hostname: page-component-78c5997874-g7gxr Total loading time: 0 Render date: 2024-11-10T10:59:24.589Z Has data issue: false hasContentIssue false
  • English
  • Français

Mesoscale exploitation of a major tuna concentration in the Indian Ocean

Published online by Cambridge University Press:  10 June 2008

Alain Fonteneau ,
Vincent Lucas ,
Emilie Tewkai ,
Alicia Delgado  and
Hervé Demarcq
Alain Fonteneau
Affiliation:
IRD Scientist, CRH, BP 171, 34203 Sète Cedex, France
Vincent Lucas
Affiliation:
SFA Scientist, PO Box 449, Victoria, Seychelles
Emilie Tewkai
Affiliation:
IRD Scientist, CRH, BP 171, 34203 Sète Cedex, France
Alicia Delgado
Affiliation:
IEO Scientist, Centro Oceanografico de Canarias, Santa Cruz de Teneriffe, Canary Islands, Spain
Hervé Demarcq
Affiliation:
IRD Scientist, CRH, BP 171, 34203 Sète Cedex, France
Get access

Abstract

The paper analyzes the daily catch, fishing effort and fish size data of the purse seine fleet fishing in the western Indian Ocean in February 2005, when a major concentration of tuna occurred and was heavily exploited by this surface fishery. This tuna concentration event occurred over a period of just 12 days, in an area of about 3500 square nautical miles located to the west of the Seychelles. This small stratum produced a total catch of 22 000 t, corresponding to 6.5% of the total fishing mortality of all adult yellowfin (Thunnus albacares) in the entire Indian Ocean in 2005. Sets were made mainly on free schools and the catch mainly composed of large yellowfin tuna. The average CPUE and the average catch per set were very large, 65 t and 85 t per fishing day, respectively. This “event” took place in a precise area where a high concentration of chlorophyll had been localized 18 days before. The subsequent concentration of tuna schools probably arose due to the high densities of their prey feeding on this large phytoplankton biomass. This phytoplankton bloom was observed at the edge of an anticyclonic eddy, but its origin and its high density cannot be fully explained by available environmental data. The adult yellowfin were probably at a reproductive stage and actively feeding on the local food chain generated by the phytoplankton bloom. Such an event is extreme, but typical of tuna purse seine fisheries where fleets often search for such tuna patches. These events play an important role in tuna fisheries due to the increase in fishing effort and fishing efficiency of purses seiners, both of which increase their impact on the resource. The fine scale study of such events and their improved integration into tuna stock assessments is recommended.

Keywords

YellowfinConcentrationExploitationPhytoplankton bloomPurse seinerIndian Ocean
Type
Research Article
Information
Aquatic Living Resources , Volume 21 , Issue 2 , April 2008 , pp. 109 - 121
Copyright
© EDP Sciences, IFREMER, IRD, 2008

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

Bakun, A., 2006, Fronts and eddies as key structures in the habitat of marine fish larvae: opportunity, adaptative response and competitive advantage. Sci. Mar. 70, 105–122. CrossRef
Fonteneau A., 1986, Analysis of exploitation of some yellowfin tuna concentrations by purse seiners during the period 1980–1983 in the East Atlantic. Collect. Vol. Sci. Pap. ICCAT 25, pp. 81–98.
Gaertner D., Pallares P., 2001, The European Union Research project “Efficiency of the tuna purse seiners and effective efforts” ESTHER. SCTB14 working paper, Fishing technology working group.
Gaertner D., Delgado de Molina A., Pallares P., Santana J.C., 2002, Some relationships between the behaviour of the European purse seiners for tropical tunas and the catches obtained. ICCAT Collect. Vol. Sci. Pap. 54 (1), pp. 91–95.
Hassani S., Stéquert B., 1991, Sexual maturity, spawning and fecundity of the yellowfin tuna (Thunnus albacares) of the Western Indian Ocean. Coll. Vol. IPTP Doc. 4, pp 91–107.
IOTC 2005, Report of the 7th session of the IOTC working party on tropical tunas. IOTC Document, 48 p.
IOTC 2007, Report of the 9th session of the IOTC working party on tropical tunas. IOTC Document, 44 p.
Karpinski B., Hallier J.P. 1988, Preliminary results on yellowfin spawning in the western Indian Ocean. IPTP Expert Consultation on Stock Assessment of Tunas in the Indian Ocean, Doc. IPTP TWS/88/31.
Levitus S., Boyer T., 1994, World Ocean atlas, Volume 4: temperature. US Department of Commerce, Washington D.C.
Lima, I.D., Olson D.B., Doney S.C., 2002, Biological response to frontal dynamics and mesoscale variability in oligotrophic environments: Biological production and community structure, J. Geophys. Res., 107(C8), 3111, doi:10.1029/2000JC000393.
Palacios D.M., Bograd S.J., Foley D.G., Schwing F.B., 2006, Oceanographic characteristics of biological hot spots in the North Pacific: A remote sensing perspective. Deep-Sea Res. II, 53, 250–269.
Potier, M., Marsac, F., Cherel, Y., Lucas, V., Sabatier, R., Maury, O., Ménard, F., 2007, Forage fauna in the diet of three large pelagic fishes (lancetfish, swordfish and yellowfin tuna) in the western equatorial Indian Ocean. Fish. Res. 83, 60–72. CrossRef
Ravier C., Marsac F., Fonteneau A., Pallares P., 2000, Contribution to the study of tuna concentrations in the eastern Tropical Atlantic Ocean. ICCAT Collect. Vol. Sci. Pap. 51(1), pp. 699–713.
Stéquert, B., Rodriguez, J.N., Cuisset, B., Le Menn, F., 2001, Gonadosomatic index and seasonal variations of plasma sex steroids in skipjack tuna (Katsuwonus pelamis) and yellowfin tuna (Thunnus albacares) from the western Indian ocean. Aquat. Living Resour. 14, 313–318. CrossRef
Stretta J.M., 1991, Forecasting models for tuna fishery with aerospatial remote sensing. Int. J. Remote Sensing, 12, 771–779.
Timochina O.I., Romanov E., 1991, Note on reproductive biology of yellowfin tuna in the Western Indian Ocean. Document 91/08, IPTP workshop on stock assessment of yellowfin tuna.
Zainuddin, M., Kiyofuji, H., Saitoh, K., Saitoh, S.I., 2006, Using multi-sensor satellite remote sensing and catch data to detect ocean hot spots for albacore (Thunnus alalunga) in the northwestern North Pacific. Deep Sea Res. II 3, 419–431. CrossRef