2009 - INIDEP Informe Técnico Nro 68-77

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    Estimaciones de la biomasa de merluza (Merluccius hubbsi) en los sectores argentino y uruguayo de la Zona Común de pesca argentino-uruguaya (34º 00º S-39º 30º S) Y en el área que se extiende hasta 41º S (ZEE Argentina) en 1994, 1996-2001 y 2003
    (Mar del Plata: Instituto Nacional de Investigación y Desarrollo Pesquero, 2009) Bezzi, S.I.; Ibáñez, P.M.
    Hake (Merluccius hubbsi) biomass in the Argentine and Uruguayan sectors of the Argentine-Uruguayan Common Fishing Zone (AUCFZ) and in the area that extends from the limit of the shared zone to 41° S was estimated (SW Atlantic Ocean). The contribution to the strata total biomass in each sector was analyzed and complemented with observations on the structure of the population. The basic data to estimate biomass derived from the evaluation surveys of the Hake Project carried out in winter or spring 1994, 1996-2001 and 2003. In 1999 biomass north of 41° S decreased to 30. (112,280 t) of the estimates made for 1994. In 2000 it increased to 165,000 t and in 2003 it was estimated at 156,407 t. A remarkable decrease of the AUCFZ percentage of contribution to the total biomass north of 41° S was registered. The result was an increase of the contribution corresponding to the intermediate zone that in 2003 contributed 54. of the total biomass. The modal class was equal to or smaller than 25 cm in the Uruguayan sector, between 13-37 cm in the Argentine sector and smaller than 35 cm in the intermediate zone where it reached 22 cm in 2000 and 27 cm in 2001. The rest of the years it varied between 38-41 cm. In the intermediate zone the average length and the modal class were larger than in the AUCFZ sectors.
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    Pesca comercial y captura por unidad de esfuerzo de la merluza (Merluccius hubbsi) entre 34º S-41º S durante el período 1986-2005 y evidencias sobre cambios en la distribución y composición por tallas del recurso
    (Mar del Plata: Instituto Nacional de Investigación y Desarrollo Pesquero, 2009) Irusta, G.; Castrucci, R.; Simonazzi, M.
    The activity of the hake (Merluccius hubbsi) commercial offshore ice chilling fleet and its relation to concentration, distribution and population areas of the stock distributed between 34ºS - 41ºS is described. The catch per unit of effort (CPUE) for the 1986-2005 period was estimated applying the General Linear Model. Data derived from the offshore fishing logs provided by the Argentine Secretary of Agriculture, Farming, Fishing and Food Administration and the information obtained in research cruises carried out in 1994, 1996-2001, 2003-2005 to evaluate the resource population abundance. During the main fishing time in the sector (quarter 2) and up until 1991 the fleet scattered within the Argentine-Uruguayan Common Fishing Zone (SW Atlantic). Later on the activity concentrated south of 39ºS where catches and the nominal effort reached their maximum value to decrease northerly as a result of the depletion of stock concentration and the development of the hake fishery in the Patagonian area. The zone south of 39º S is a sector of low concentrations where adult individuals prevail and a transfer zone of the fleet towards Patagonian fishing grounds (41ºS - 48ºS). The annual CPUE estimated with the General Linear Model decreased by 49% in the study period. As of 2000 the fishery became variable as regards catches, fishing effort and operation areas and more dependent on important recruitments as a consequence of the marked decrease of adults population abundance.
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    Crecimiento de la merluza (Merluccius hubbsi) del Atlántico sudoccidental entre 1993-2003 al norte y sur de 41º S
    (Mar del Plata: Instituto Nacional de Investigación y Desarrollo Pesquero, 2009) Renzi, M.A.; Santos, B.A.; Abachian, Viviana
    The reading of otoliths sagittae collected during the INIDEP (National Institute for Fisheries Research and Development, Argentina) assessment cruises carried out in the 1993-2003 period allowed to estimate length and weight growth parameters and the condition factor of hake (Merluccius hubbsi) and to prospect the two management units of the species north and south of 41ºS (Argentine Sea, SW Atlantic). A great variability in total length and weight in each age group was observed; nevertheless, stable mean length and weight values per age group were observed in the period analyzed. Besides, the values estimated to determine possible growth variations in each and between both management units north and south of 41ºS were compared. The comparison of growth curves of males and females in each area showed highly significant differences. When each sex between stocks was compared, some years those differences were observed for growth as a whole and only for some parameters in others.
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    Alimentación de la merluza (Merluccius hubbsi) en el Golfo San Jorge y aguas adyacentes
    (Mar del Plata: Instituto Nacional de Investigación y Desarrollo Pesquero, 2009) Sánchez, F.
    The information obtained in summer research cruises carried out in 1995, 1999 and 2002 allowed to determine the trophic spectrum of common hake (Merluccius hubbsi) and to estimate anchovy (Engraulis anchoita) and hake consumption in the nursery area of the San Jorge Gulf and shelf adjacent waters (Argentine Sea, SW Atlantic). The area surveyed extended from 44ºS to 47ºS and between the 50-100 m isobaths. In the stomach content the most frequent items were crustaceans followed by fish. In all size groups sampled the presence of anchovy and common hake was observed. In the area assessed consumption of anchovy, weighted for the three summer months of 1995 was 56,639 t. The greatest predation pressure was observed on classes between 14-16 cm TL. Hake consumption estimated at 16,797 t in summer 1995 reached 36,456 t in 2002. The average length of common hake preys was 16 cm TL in 1995 and 13 cm TL in 2002.
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    Muestreo de desembarque de caballa (Scomber japonicus) en el puerto de Mar del Plata, período noviembre 2003-diciembre 2004 y resultados de la campaña de estimación de la biomasa de diciembre de 2004
    (Mar del Plata: Instituto Nacional de Investigación y Desarrollo Pesquero, 2009) Perrotta, Ricardo G.; Garciarena, A. David; Madirolas, A.; Cabreira, Ariel G.
    Chub mackerel (Scomber japonicus) landings corresponding to November 2003-January 2004 and November 2004-January 2005 fishing seasons were analyzed at the Mar del Plata port (Argentina, SW Atlantic). Fourty one samples were taken to measure total length exclusively and 4 sub-samples to record individual data (total length, weight, sex, sexual stage, age according to otoliths reading). Total length ranged 20-50 cm (1 and 8 years old). The most abundant sizes, between 32-37 cm, corresponded to ages 3 and 4, respectively. Most of the fish caught were adult (95%) and mature (85%) specimens. Length-weight, length-age relations were calculated and length-growth, weight-growth parameters estimated. The catch per unit of effort, of high variability (0-2,455 kg h-1), decreased as sea surface temperature increased. To estimate the species biomass in the fishing area a research cruise was carried out between 17-20 December 2004. Measurements, obtained with acoustic methods, reached a total of 11,678 t. The highest concentrations were found at a temperature of around 17.4 ºC and salinity of 33.62 psu. During the acoustic tracking, unusual concentrations of anchovy for the season were detected.
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    Las condiciones oceanográficas en el área marplatense (37° 00' S-38° 24' S) y su relación con la distribución de la caballa (Scomber japonicus). Octubre-noviembre de 1999
    (Mar del Plata: Instituto Nacional de Investigación y Desarrollo Pesquero, 2009) Reta, Raúl; Perrotta, Ricardo G.; Garciarena, A. David
    Results obtained during a research cruise carried out along the coastal area of Mar del Plata (Buenos Aires, Argentina) in November 1999 are presented. The objective of the research cruise was to estimate chub mackerel (Scomber japonicus) abundance with acoustic methods and establish its relation to the hydrographic conditions. The information gathered was complemented with data of catches obtained by a commercial vessel that operated simultaneously in the study area. Environmental data from other research cruises and satellite information were also taken into account to obtain contemporary sea surface temperature and wind speed and direction data. The main species of catches of the research cruise and commercial vessel were horse mackerel (Trachurus lathami) and anchovy (Engraulis anchoita). No chub mackerel was detected during the acoustic assessment; however, the species was caught by the commercial vessel in the southern part of the study area and near the thermohaline front. Chub mackerel yields were very low if compared to those regularly recorded in the area and time the purse-seine fleet operates and that are typical of an advanced fishing season (January). The advection of estuarine waters from the de la Plata river, conditioned by the winds field, generated the displacement of low salinity waters over the coastal area that surpassed the regular southern limits. The positive anomalies of sea surface temperature in the region, that reached values close to 3 °C, could have caused the partial exclusion of chub mackerel in the coastal region of Mar del Plata.
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    Clave de identificación de cápsulas de huevos de condrictios del Mar Argentino
    (Mar del Plata: Instituto Nacional de Investigación y Desarrollo Pesquero, 2009) Mabragaña, Ezequiel; Figueroa, Daniel E.; Scenna, Lorena B.; Díaz de Astarloa, Juan Martín; Colonello, Jorge H.; Massa, Ana M.
    Twenty eight species of oviparous chondrichthyans were reported on the Argentine Continental Shelf (SW Atlantic). The egg cases laid on the sea bed provide useful information to identify species, eggs laying areas and seasons. Based on the analysis of 155 egg cases corresponding to 21 chondrichthyan species, an illustrated field guide for a correct identification is presented.
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    Análisis de la utilización de la captura por unidad de esfuerzo de pescadilla de red (Cynoscion guatucupa) como índice de abundancia anual. Período 1992-2004
    (Mar del Plata: Instituto Nacional de Investigación y Desarrollo Pesquero, 2009) Perrotta, Ricardo G.; Ruarte, Claudio
    The stripped weakfish (Cynoscion guatucupa) caught in Brazil, Uruguay and Argentina (SW Atlantic) has a wide latitudinal distribution (22° S-43° S). In Argentina there are two main fishing areas, the Argentine-Uruguayan Common Fishing Zone and 'El Rincón', southern zone of the Buenos Aires littoral. The importance of the species makes it necessary to define an annual abundance index that would allow to diagnose the state of the stock. The model adjusted to calculate the index is the General Linear Model. The factors used were Year, Quarter, Length, Stratum (4 categories) and sub-areas (5 categories), all statistically significant. The problem generated by the presence in the model of first order interactions that include the Year factor is discussed. The importance of said interactions is assessed pursuant to the percentage of variance explained considering the model with and without such interactions. It is concluded that the catch per unit of effort series reflects space-temporal changes in the fleet activity not proportional to the biomass.
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    Evolución reciente de la captura por unidad de esfuerzo (1993-2004) y de las tallas medias (1993-2005) del pez palo (Percophis brasiliensis) en el litoral marítimo entre 34º S y 42º S
    (Mar del Plata: Instituto Nacional de Investigación y Desarrollo Pesquero, 2009) Rico, María Rita; Perrotta, R.G.
    Brazilian flathead (Percophis brasiliensis), of wide latitudinal distribution (23° S-47° S), is caught in Argentina in two coastal areas north and south of the Province of Buenos Aires delimited by the 39° S latitude. The species shows the highest abundance and catch yield percentages ( 5. ) of all coastal fish groups. The importance of the species makes it necessary to analyze mean lengths and define an annual abundance index that would allow to diagnose the state of the stock. To calculate the index the General Linear Model was adjusted. The factors used were Year, Quarter and 4 sub-areas, all statistically significant. The problem generated by the presence in the model of first order interactions that include the Year factor is discussed. It is concluded that the catch per unit of effort series did not represent changes in the resource abundance. Results suggest that caution should be taken when using the values normally considered to diagnose the state of the stock and implement management measures. Based on catch and effort values, the most important sub-areas were the mouth of the Río de la Plata river (1) and the Mar del Plata adjacent areas (3). A decreasing trend of the mean length throughout the study period was also observed.
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    Inventario íctico del litoral costero bonaerense y uruguayo
    (Mar del Plata: Instituto Nacional de Investigación y Desarrollo Pesquero, 2009) Ruarte, Claudio; Rico, María Rita; Lucifora, L.
    The bibliography and the registries of fish caught in the Buenos Aires (Argentina) and Uruguay coastal littoral area during 33 research cruises were analyzed to elaborate the first ichthyic inventory of the region. A total of 147 species belonging to 71 families was registered. The figure represents 48% of the specimens reported for the Argentine-Uruguayan Common Fishing Zone and 37% of the marine species mentioned for the SW Atlantic. The list of coastal marine fishes of Uruguay and north of Argentina is the first attempt to provide basic information to evaluate possible temporal changes of the ichthyic composition in the area. The lists or inventories constitute an essential tool for fisheries management, the generation of statistic data and gathering of information useful for resource assessment.