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Fishery biology and life history of Illex argentinus
Brunetti, N.; Ivanovic, M.; Rossi, G.; Elena, B.; Pineda, S. (1998). Fishery biology and life history of Illex argentinus, in: Okutani, T. Contributed papers to International Symposium on Large Pelagic Squids, July 18-19, 1996, for JAMARC's 25th anniversary of its foundation. pp. 217-231
In: Okutani, T. (1998). Contributed papers to International Symposium on Large Pelagic Squids, July 18-19, 1996, for JAMARC's 25th anniversary of its foundation. Japan Marine Fishery Resources Research Center: Tokyo. 269 pp., more

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Keyword
    Marine

Authors  Top 
  • Brunetti, N.
  • Ivanovic, M.
  • Rossi, G.
  • Elena, B.
  • Pineda, S.

Abstract
    Illex argentinus, the most abundant ommastrephid squid in the southwest Atlantic, inhabits the area between 54°S and 23°S, but the highest concentrations occur southward 40°S, in shelf waters of subantarctic origin (8°C-12°C). On the basis of size structure, length at maturity and, area and time of spawning, the existence of at least four stocks in the area off Argentina has been postulated. The Bonaerensis-Northpatagonic Stock (BNPS) occurs on the external shelf and slope between 37°S and 43°S during May-July and would spawn on the slope during winter. The Southpatagonic Stock (SPS) , the largest and which supports the highest fishery pressure, is distributed in the area between 43°S and 50°S during February-May and its spawning would take place in the slope area during autumn. Adults of both stocks reach large sizes (25-39 cm ML) and their paralarvae share the same distributional area, in the western boundary of Brazil-Malvinas Confluence. The migration pattern of both stocks would be characterized by: irnmigration of paralarvae and juveniles to the bonaerensis intermediate shelf and movement to the nursery and trophic areas in the south during winter (SPS) and spring (BNPS) , and emigration, from shelf to slope, of preadults and adults to the reproductive and spawning areas during summer (SPS) and autumn (BNPS) .Summer Spawning Stock (SSS) is limited to the shelf area between 42°S-48°S and comprises small squid that reach maturity at small sizes (14-25 cm ML) .They spawn during summer and their paralarvae are found together with them. Northward, between 38°S-40°S, large spawning and spent individuals of the Spring Spawning Stock (spss) are found together with paralarvae during spring. Illex argentinus feeds mainly on zooplankton, although some differences in the relative proportion of the main prey were detected between the bonaerensis and patagonian regions. While zooplankton represents almost the exclusive prey in the patagonian area (85.29% percentage occurrence) , in the bonaerensis shelf it is still the most abundant (56.96%) , but fish and squid account for a significative proportion of the diet (29.41% and 13.62%, respectively). Argentine fishery activities on squid began in 1993, when a jjgger fleet started to operate on them. Before that, the species was caught only as an alternative by the trawler fleet directed mainly to hake. Catches were not significant until years 1978-79 when a high increment, up to reach 90,000 t, was detected. Then they decreased again until 1993, when they increased sharply to reach a maximum of about 200,000 t per year. Besides, an intensive fishery activity is performed in the Malvinas shelf area and the international waters adjacent to the Argentinian Exclusive Economic Zone since 1987. Most of this fishery develops during February- June on the SPS, following the squid rnigration from shelf to slope.

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