Dépôts récents

  • Oceanographic conditions at the southern end of the argentine continental slope

    Guerrero, R.A.; Baldoni, A.G.; Benavides, H.R. (Mar del Plata: Instituto Nacional de Investigación y Desarrollo Pesquero, 1999)
    INIDEP documento científico
    The characteristics of the upper Antartic Intermediate water (AAIW) entering the Southern Atlantic are described on the base of oceanographic data collected from four late austral winters (1978-1980-1994-1995). The upper 500 meters regime along the shelf break and around Malvinas Islands (48° to 55° S) is analyzed. In particular, the 1994 horizontal distribution of temperature, salinity and density was mapped in order to show the extreme winter pattern of these parameters. Three salinity sections crossing the water flow direction in the Malvinas Channel (South to the islands) were selected to describe the vertical stratification 1995 and 1995. Horizontal and vertical distribution of chlorophyll a from the 1995 cruise is presented as reference data, considering the lack of information on this parameter for the area. Finally, the inter-annual variability of the heat content in two 5° x 5° areas (East and West to the islands) is discussed by comparing the Sea Surface Temperature (SST) data between the four sampled years. From this information, 1995 resulted in the coolest winter, presenting a temperature anomaly around -4° C respect to theother winters.
  • Ichthyoplankton composition, distribution and abundance on the southern patagonian shelf and adjacent waters.

    Ehrlich, M.D.; Sánchez, R.P.; de Ciechomski, J.D.; Machinandiarena, L.; Pájaro, M. (Mar del Plata: Instituto Nacional de Investigación y Desarrollo Pesquero, 1999)
    INIDEP documento científico
    This paper reviews the information on pelagic and demersal fish eggs and larvae, describing the distribution and seasonality of different species and their arrangement in icthyoplankton assemblages in the Southern patagonian waters. It also reports on 11 surveys conducted by INIDEP during 1992-1995. A total of 488 ichthyoplankton samples were analyzed. Fish eggs have been recognized in 47. of all ichthyoplankton samples. They belong to three species: Coelorhynchus fasciatus, Macrourus whitsoni and Micromesistius australis. Fish larvae of 23 species and 17 families have been identified in 96. of all samples analyzed. Spawning of most species begins in autumn, and progresses through winter, when the southern blue whiting and grenadier fish contribute to more than half of all eggs present in our samples. Nototheniid and myctophiid larvae were caught during all year long. Four larval groups were detected using cluster analysis: the first group, formed exclusively by nototheniids, which occupied a vast area on the continental shelf between 100 and 200 m depth, the second formed by Agonopsis chiloensis, Eleginops maclovinus, Macruronus magellanicus and Sprattus fuegensis in coastal waters, the third formed by myctophiids, Gymnoscopelus spp. and Micromesistius australis, inhabit the outer continental shelf and slope, and the fourth included Protomyctophum spp., Krefftichthys anderssoni and Bathylagus antarcticus, species typically found in Subantarctic waters of the Malvinas Current. Comparing the distribution of eggs and larvae of blue whiting from collections obtained during the 70's and 80's, with those of recent surveys, it is evident, that a significant contraction of the spawning grounds of the species has take place, particularly to the west of the archipelago.
  • Características de la red de cerco "tipo lámpara" y algunos comentarios sobre la flota que la utiliza en la pesca de caballa.

    Izzo, A.; Boccanfuso, J. (Mar del Plata: Instituto Nacional de Investigación y Desarrollo Pesquero, 1993)
    INIDEP documento científico
    The composition of the fleet is analyzed. The boats range 50-200 HP of engine and have 9-16 m in length overall. Most of the boats have been improving their equipment (echosounders, new engines) since 1980. An inverse relationship was found between sea surface temperature and CPUE as measured by mackerel catch permit time spent on fishing gounds. Yields are negligible over 20°C with a optimum of 20°C.
  • Presencia de veneno paralizante de moluscos en higado de caballa de la región costera bonaerense

    Carreto, J.I.; Akselman, R.; Cucchi Colleoni, A.D.; Carignan, M.O.; Pájaro, M. (Mar del Plata: Instituto Nacional de Investigación y Desarrollo Pesquero, 1993)
    INIDEP documento científico
    During november 1992 an intense bloom of the toxic dinoflagellate Alexandrium tamarense accurred in coastal waters from Mar del Plata, Argentina. Toxicity testing of Mytilus edulis populations of the region revealed high levels of paralytic shellfish poison. In order to study the possible PSP accumulation in mackerel (Scomber japonicus), mouse bioassay(AOAC) was performed in livers from individuals captured during December 1992. Liver extracts were lethal to mice; the sumptoms observed were typical of those caused by paralytic shellfish toxins. Although PSPS concentration is below the established limit for human consumption, it suggests that mackerel can accumulate PSP toxins from its food. On the basis of stomach content analysis of sampled mackerel and the related literature, the occurrence of possible toxins vector organisms is discussed.
  • Sobre la dinámica poblacional de la caballa en la pesquería de Mar del Plata. Período 1980-1990

    Perrotta, R.G.; Pertierra, J.P. (Mar del Plata: Instituto Nacional de Investigación y Desarrollo Pesquero, 1993)
    INIDEP documento científico
    This species is a principal basic product of the local canned industry. The results show that the biomass and capture were variable for the studied period as a consequence of change in the capturability, and the fishstock is underexploited. Also was estimated the contribution of recruitment, growth and mortality in the total biomass.
  • Comparación mediante el empleo de los caracteres merísticos y el crecimiento de caballas originarias de varias regiones geográficas (Cataluña, Islas Canarias y Sudamerica).

    Perrotta, R.G. (Mar del Plata: Instituto Nacional de Investigación y Desarrollo Pesquero, 1993)
    INIDEP documento científico
    Mackerel from SW Atlantic (22° -39°S) and the coast of Cataluña (42° 30'N) were compared by analizing both morphometric and meristic characters. A multivariate analysis, i.e. principal components was used. The growth curves corresponding to mackerels from different regions (Canarias, North of Chile, Mar del Plata and Rincón in Argentine) were also compared, as well as the mean length at ages 1 and 2 (Mar del Plata- Cataluña, Rincón- Cataluña). Significant differences in the growth were found between two groups. The first group was integrated by three SW Atlantic population (Brasil, Mar del Plata, Rincón), which possible conform a subspecies of Scomber japonicus. The second one was represented by the coastal mackerel off Cataluña.
  • Consideraciones sobre la alimentación de la caballa con especial enfasis en la depredación de huevos y larvas de peces

    Pájaro, M. (Mar del Plata: Instituto Nacional de Investigación y Desarrollo Pesquero, 1993)
    INIDEP documento científico
    Adult and juvenile fish inter and intraspecific predation may be an important source on these first development stages. In this work, adult and juvenile mackerel samples from two areas of Buenos Aires province, one south of Cape San Antonio and the other near Mar del Plata city were analyzed. An important anchovy postlarvae ingestion in both regions considered was observed. A high number of mackerel eggs in the stomach contents from adults was identified. This evidence of cannibalistic behaviour in the argentine mackerel is the first of its kind made in this species and allows to suggest that embryo mortality due to cannibalism might constitute and important percentage of the total embryonic mortality.
  • Zooplankton biomass in the reproductive area of the southern blue whiting (Micromesistius australis).

    Sabatini, M.; Alvarez Colombo, G.L.; Ramirez, F.C. (Mar del Plata: Instituto Nacional de Investigación y Desarrollo Pesquero, 1999)
    INIDEP documento científico
    Total and size-fractioned zooplankton biomass (larger and smaller than 5 mm) were analyzed over two cruises conducted in the late austral winter (September 1994 and 1995) in the area surrounding Malvinas Islands at the time that massive spawning of southern blue whiting was expected to take place. Biomass was rather uniformly distributed in the area and dominated by the fraction larger than 5 mm in which euphausiids and secondarily chaetognaths were dominating in terms of both weight and number. The smaller fraction was mostly made up of copepods. From the high occurrence of euphausiids and seasonal abundance of the several species of copepods normally present within the area it was hypothesised that the feeding requirements of juvenile and adult blue whiting as well as those of larvae and postlarvae may be met during the winter spawning season. The data were also examined in conjunction with the general pattern of zooplankton biomass occurring in autumn and spring in the Southern Patagonian shelf.
  • Acoustic surveys on the southern blue whiting (Micromesistius australis).

    Madirolas, A. (Mar del Plata: Instituto Nacional de Investigación y Desarrollo Pesquero, 1999)
    INIDEP Documento Científico
    Two joint Argentine-British acoustic surveys specifically targeted on the southern blue whiting (Micromesistius australis) were carried out during September 1994 and 1995. The surveys confirmed the existence of a spawning concentration area located south from San Carlos Strait, in waters south of Malvinas Islands, ASW. The obtained point estimates of blue whiting abundance were 84801 t for the 1994 survey and 140953 t for the 1995 survey. The surveys also provided information on the school structure and behavior as well as some clues about the complex migration pattern of the species.
  • Features of the reproductive biology of the southern blue whiting (Micromesistius australis).

    Macchi, G.J.; Pájaro, M. (Mar del Plata: Instituto Nacional de Investigación y Desarrollo Pesquero, 1999)
    INIDEP documento científico
    Different features of the reproductive biology of the southern blue whiting (Micromesistius australis) are analyzed. Samples were obtained from research cruises and from commercial catches carried out between March-November 1995, in waters near Malvinas Islands. Reproductive activity of M. australis was observed between the end of July and September, southwest of Malvinas Islands. Oocyte diameter distribution of gravid females and the histological observations show that this species is a batch spawner with determinate annual fecundity. Preliminary estimate of the potential annual fecundity was about 478,000 oocytes for a 51-cm mean total length. Size at first maturity for this species was about 31 cm total length.
  • Conocimiento biológico pesquero del recurso merluza (Merluccius hubbsi) y su pesquería en la República Argentina.

    Bezzi, S.I.; Dato, C.V. (Mar del Plata: Instituto Nacional de Investigación y Desarrollo Pesquero, 1995)
    INIDEP documento científico
    This paper summarizes the present knowledge on Merluccius hubbsi and its fishery in Argentina, based on the model proposed by the Technical Secretary of Comisión Técnica Mixta del Frente Marítimo, in 1990. It includes the taxonomic location of the species, its geographical distribution, stock unity, structure and population dynamics. It describes the fishing gear and fishing operations and presents the available information on selectivity and discards. The paper shows the data landings separated by fleet. Exploitation regulatory measures in force are included.
  • Ecología trófica de la merluza común (Merluccius hubbsi) del Mar Argentino. Parte 3. Consumo anual de alimento a nivel poblacional y su relación con la explotación de las pesquerías multiespecíficas.

    Prenski, L.B.; Angelescu, V. (Mar del Plata: Instituto Nacional de Investigación y Desarrollo Pesquero, 1993)
    INIDEP documento científico
    The English contents gives a general view on the topics treated in this contribution developed mainly on the basis of a quantitative and ecological analysis of trophic relationships in the Argentinian Continental Shelf, in which common hake and its food species are involved (anchovy, mictophids, small fishes, squids and macrozooplankton crustaceans). The most original part consist in the application of bioenergetic and simulation models for estimating the annual food consumption by individuals and by stocks of common hake during 1970-1987, considering at the same time, the effects of commercial catches on the stockbiomasses in predator-prey relationships. From this point of view three trophic-fishery relationships are evident, namely: "Common hake-Anchovy"; "Common hake-squids" and "Common hake-Common hake". The first one refers to a potential fishery, since the anchovy stocks are not yet intensively exploited; in the second relationship, the stocks of both integrant species makes the object of the main argentinian marine commercial fisheries; and the third corresponds to cannibalism. Consequently, the importance of the "tropic catch", that is to say, the food biomass consumed by the common hake stocks (corresponding to a part of the natural mortality M) and the necessity to consider this catch together with the commercial catch to attain a complete management strategy for the multispecies fisheries in the region of the Argentinian Continental Shelf.
  • Report of the INIDEP working group on assessment of hake (Merluccius hubbsi) north of 48° S (Southwest Atlantic Ocean)

    Bezzi, S.I.; Cañete, G.R.; Pérez, M.; Renzi, M.A.; Lassen, H. (Mar del Plata: Instituto Nacional de Investigación y Desarrollo Pesquero, 1994)
    INIDEP documento científico
    The assessment covers hake between 34° and 48°S (Argentina and Uruguay), excluding Golfo San Matías. Total international landings and Argentine catch-at-age and effort data available for the 1983-1991 period allowed an analytical assessment. Tunning of the VPA was made using Laurec-Shepherd analysis and Extended Survivor analysis. The results of these analysis are congruent with the information about the state of the stock. VPA biomass estimates are aound 2.1 and 2.7 mill. Tonnes, which are similar to those calculated through surveys. The Spawning Stock Biomass estimated for 1991 is considered to be within limits where the stock shows stable recruitment. At the present effort level, yield and Spawning Stock Biomass appear to remain stable. Management measures are also discussed.
  • Estimación cuantitativa del descarte en la pesquería de merluza realizado por la flota comercial argentina

    Dato, C.V.; Bambill, G.A.; Cañete, G.R.; Villarino, M.F.; Aubone, A. (Instituto Nacional de Investigación y Desarrollo Pesquero (INIDEP), Mar del Plata, 2006)
    INIDEP documento científico
    Based on the comparison between length composition of landings and that of research cruises, filtered by the selectivity of the mesh used by the commercial fleet, to rebuild length distribution of catches, an indirect quantitative method was developed and used to estimate, in weight and number, the individuals discarded by the commercial fleet south of 41° S. Discards ranged between 15,563 and 46,113 annual tons in the 1986-1993 period which represented 10-13% in weight and 28-32% in number of actual catches, composed of around 87% of individuals age group 1, 12% of age group 2 and the rest of individuals age groups 0 and 3.
  • Áreas potenciales de descarte de merluza para la actividad de la flota comercial argentina

    Dato, C.V.; Villarino, M.F.; Cañete, G.R. (Instituto Nacional de Investigación y Desarrollo Pesquero (INIDEP), Mar del Plata, 2006)
    INIDEP documento científico
    To improve the quality of the resource assessment it is necessary to estimate discards and quantify them applying an adequate methodology. The purpose of this work is to detect areas where the activity of the commercial fleet coincides with zones of high concentration of juveniles because they are potential discard areas. To establish possible seasonal and/or interannual variations, length distribution data derived from hake research surveys carried out on board of INIDEP vessels during the 1986-1993 period were analyzed. Samples were grouped per statistical rectangle on the basis of catch weighted average and mean, variance, skewness and kurtosis were calculated. The resulting parameters were subjected to a cluster analysis using the Euclidean distance and Ward index. Besides, juveniles percentage (individuals below 35 cm total lenght) and sex proportion per statistical rectangle and season were calculated. To analyze the dynamics of the commercial fleet, catch and effort data for the same period were used. Results indicate that the areas of highest concentrations of juveniles are located north of 37° S and southwards between 43° S and 47° S, from the coast to 62° W, both at 50-150 m depth. The strong presence of the argentine commercial fleet in the southern area, intensified as of 1990, led to consider it a potential discard area. North of 37° S the fleet had scarce presence during the period analyzed. Neither area showed seasonal and/or interannual variations, so they were considered representative of the 1986-1993 period to estimate discards quantitatively.