Influence of shelf-break fronts on shellfish and fish stocks off Argentina

The general circulation pattern in the western boundary of the SW Atlantic is dominated by the opposite flows of Malvinas (-Falkland)and Brazil Current. In the Confluence region both currents separate from the continental slope and flow offshore creating an area of strong contracts and complex dynamics. The shelf-break fronts off Argentina mark the transition between shelf waters of mixed origin and nutrient rich Malvinas waters. Two areas deserve special attention due to the steep gradients introduced by the outflow of important sources of continental waters: the Rio de la Plata and the Magellan Strait to the north and south of the study area. Characteristics of the front is the high primary and secondary production, and the presence of important invertebrate and fish stocks that concentrate along the front to feed or spawn. The area comprises nearly 30 o/o (333 million U$S in 1995)of all Argentine catches of fish and squid. Resources in the area, beyond the EEZ limits, support international fisheries mainly of Russia, Poland and Spain

Distribucion de tallas y biologia reproductiva del calamar (illex argentinus) en el mar argentino (Campanas del B/I "Shinkai Maru", 1978-1979)

Length distribution and reproductive biology of Illex argentinus in the Argentine Sea.(April 1978-April 1979). Size measurements of 13,989 specimens of Illex argentinus were made by japanese scientists on board of the R/V "Shinkai Maru", during the exploratory cruise carried out by that ship in the Argentine Sea from April 1978 to April 1979. Samples were analyzed by the author on land, with determination of size, sex and maturity stage

Escala para la identificacion de estadios de madurez sexual del calamar (illex argentinus)

Se presenta una escala para la identificaciön de estadios de desarrollo sexual, de ambos sexos, del calamar ( lllex argentinus). Ella permite la discriminaciön de siete estadios en los machos y ocho en las hembras. La escala propuesta para las hembras tiene en cuenta los cinco estadios ovaricos enunciados por Schuldt (1979) mediante el analisis histolögico, asl como Indices gonadosomaticos y nidamentales. La escala considera las caractensticas propias (estructura, color, forma) y rrtodificaciones de las gonadas, ductos y glandulas accesorias, durante los diferentes estadios de ambos sexos

The evolution of the Illex argentinus (Castellanos, 1960)

17 pages, 3 figures, 4 tablesPeer Reviewe

Description of Rhynchoteuthion larvae of Illex argentinus from the summer spawning subpopulation

The Rhynchoteuthion larvae of Illex argentinus resulting from summer spawning in North Patagonic shelf waters, its distribution and abundance, are described in this paper. The material was collected in the Argentine Sea (35–55°S) by means of plankton nets. The research cruises were made by the R/V Shinkai Maru and the R/V Walther Herwig during the period April 1978 to April 1979. The most important spawning ground of the summer spawning subpopulation is found in continental-shelf waters (between 43 and 46°S) during the period December-February. This area was established on the basis of both ripe (December) and spent females (February). The larvae which were caught during the same period, especially in March, confirmed the spawning area of this demographic unit. The larvae showed the length of the mantle (ML) to be from 1.2 to 6.5 mm. Tentacles were splitting in specimens from 5.0 to 6.5 mm ML (transition stage). When 7.0 mm ML or more, all specimens were juveniles and had their tentacles completely separated. Larvae were characterized as type C, following the proposal of Sato (1973) and Sato and Sawada (1974) in the Bulletin of the Shizuoka Prefectural Fisheries Experimental Station

Abundancia, distribucion y estructura poblacional del calamar (illex argentinus) en aguas de la plataforma patagonica en diciembre de 1986 y enero-febrero de 1987

Durante diciembre de 1986 y enero-febrero de 1987, el B/l Oca Balda realizo dos cruceros de investigacion en aguas de la plataforma Continental patagonica. El primero (OB-07-86), operö en el sector norpatagonico entre las isobatas de 50 y 100 m, teniendo como objetivo la evaluacion del stock desovante de merluza comün (Merluccius hubbsi). El segundo (OB-Ol-87), explorö las aguas de la plataforma subpatagönica desde los 46°S hasta los 55°S por fuera del ärea de exclusion de las Isias Malvinas, y tuvo por objetivo la evaluacion de las principales especies de interes comercial

Abundancia, distribucion y composicion poblacional del recurso calamar (illex argentinus) en aguas uruguayo-bonaerenses en mayo, setiembre y noviembre de 1986 y en marzo y mayo de 1987

Las capturas de calamar (Ille x argentinus) de cinco campanas de investigaciön realizadas por el B /l Oca Balda fueron procesadas mediante el metodo de ärea barrida para obtener estimaciones (en peso y nümero de individuos) de las densidades en cada lance de pesca. Utilizändose estratos de finidosa p r io r i sobre la base de la abundancia relativa de la merluza comün (Merluccius hubbsi), se realizaron las estimaciones de la biomasa del calamar, en peso y nümero, correspondientes a las campanas del ano 1986 y a la OB-03/87. Igualmente se suministra la evaluaeiön de calamar en mayo de 1987 pero sobre estratos de fin id o sa p r io r i relacionados con las zonas de concentraciön de calamar de anos anteriores