Revista de Investigación y Desarrollo Pesquero 2006 Nro 18
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- ItemCrustáceos Decápodos y Estomatópodos asociados a la pesquería del langostino patagónico Pleoticus muelleri (Bate, 1888) en el golfo San Jorge, Argentina(Mar del Plata : Instituto Nacional de Investigación y Desarrollo Pesquero (INIDEP), 2006) Roux, A.; Piñero, R.The analysis of the data obtained in five research cruises carried out during the year 2000 allowed to describe the composition, structure and distribution of decapod and stomatopod crustaceans of the benthic communities of the San Jorge Gulf associated to Patagonian red shrimp fishing grounds. Results show that decapod and stomatopod crustaceans account for 71% of the total crustacean species registered in the benthic community. Munida subrugosa is the species that presents the highest values of relative abundance, frequency of occurrence and relative importance index. The feeding habits of Libidoclaea granaria, Lithodes santolla and Peltarion spinosulum and food availability in the San Jorge Gulf fishing grounds explain the high frequency of occurrence of said species in the sector. Distribution and abundance of Pterygosquilla armata armata is also clearly related to traditional fishing grounds (IR= 51.58). Abundance and predator and scavenger behaviour of this group of species result in a “cleaning” effect on the fishing grounds thus allowing for a rapid recovery after a fishing activity period.
- ItemDistribución de huevos, larvas y prerreclutas de merluza (Merluccius hubbsi) en la Zona Común de Pesca Argentino-Uruguaya. Período 1999-2001(Mar del Plata : Instituto Nacional de Investigación y Desarrollo Pesquero (INIDEP), 2006) Machinandiarena, L.; Brown, D.R.; Ehrlich, M.D.; Pájaro, M.; Dorado, J.; Teso, V.Distribution and abundance of eggs, larvae and prerecruit stages of Merluccius hubbsi were evaluated to examine spawning, nursery and settlement areas in the Argentine-Uruguayan Common Fishing Zone during the 1999-2001 period. Larvae and prerecruit stages were more abundant at stations from 50 m to 100 m depth. The nursery area would extend from the 50 m isobath south of 37° S to the 200 m isobath northward where the shelf becomes narrower. In the whole sampling area small size prerecruits were caught; therefore, the whole zone should be considered as a potential settlement area.
- ItemGrowth in the 0-group of Argentine hake (Merluccius hubbsi) from the Argentine-Uruguayan Common Fishing Zone(Mar del Plata : Instituto Nacional de Investigación y Desarrollo Pesquero (INIDEP), 2006) Santos, B.A.; Renzi, M.A.Growth of hake (Merluccius hubbsi) in the 0-group from the Argentine-Uruguayan Common Fishing Zone was studied and spawning data were back-calculated by identifying daily growth rings in otoliths of specimens caught during research cruises performed in May 1997, May 1998 and June 1999. Total length (TL) range was 14-69 mm. Increments were read under microscope using an otolith daily ring measurement system (RATOC). Changes in the increment width data present a pattern that seemed to be similar, and independent from birth date of individuals. Data observed and back-calculated showed good accordance with the Laird-Gompertz model. Significant differences between coefficients were found in all comparisons of growth curves for observed and retrocalculated data. Growth rates estimated from observed data showed maximum values (ca. 0.54 mm d-1) at the stage of late larvae and minimum values at the stage of large early juveniles (ca. 0.25 mm d-1). For each year back-calculated hatching dates corresponded to the scarce mid-summer reproductive activity.
- ItemGrowth of Argentine silverside (Odontesthes bonariensis) stocked at low densities in two oligohaline shallow lakes (Buenos Aires province, Argentina)(Mar del Plata : Instituto Nacional de Investigación y Desarrollo Pesquero (INIDEP), 2006) Espinach Ros, A.; Dománico, A.Argentine silversides (Odontesthes bonariensis) stocked as fry (45 days old) at low densities in two oligohaline Pampasic shallow lakes (Buenos Aires province, Argentina) grew to legal harvest size (250 mm, total length) in one year, and averaged 403 mm in length and 500 g in weight after 25 months.
- ItemInfluencia de las interacciones con el factor Año en los índices anuales de abundancia obtenidos por modelos lineales generales utilizando datos de Captura por Unidad de Esfuerzo(Mar del Plata : Instituto Nacional de Investigación y Desarrollo Pesquero (INIDEP), 2006) Hernandez, D.R.; Perrotta, R.G.The problem in the definition of a relative annual abundance index using a General Linear Model is posed. The possible factors generating changes in the catch per unit effort (CPUE) are discussed and the parameterization of the model is analyzed, in particular the Sigma-restrictive parameterization. This report considers the problem caused by the presence of interactions of first order that include the factor Year in the model. It has been mathematically demonstrated that in the presence of these interactions, the index series is not proportional to the abundance annual mean of the resource. An approach of practical order to evaluate the possible effect of the interactions that include the factor Year in the index is considered using the percentage of explained variance of the model with and without these interactions. Some methodological rules are also defined to attenuate several problems generated by the mentioned interactions: (1) evaluating if type of fleet, included as categories of the factor Ship, has experienced modifications throughout the period of study that could have generated changes in the efficiency of fishing units; (2) allowing for the possibility of working with indexes pondered by Area; (3) using the most convenient categorization for the factor Month (month, bimonthly, quarterly, fishery season, etc.), considering the seasonal distribution of the resource and the activity of the fleet, as well as the limitations generated by the presence of empty cells in the design. Two application examples are presented
- ItemReproductive biology of red squid (Ommastrephes bartramii) in the Southwest Atlantic(Mar del Plata : Instituto Nacional de Investigación y Desarrollo Pesquero (INIDEP), 2006) Brunetti, N.E.; Ivanovic, M.L.; Aubone, Aníbal; Pascual, L.N.Red squid (Ommastrephes bartramii) samples were collected during six exploratory cruises carried out in the Southwest Atlantic region off Argentina and Uruguay (33° S-42° S; 43° W-55° W) during summer-autumn of the period 1997-2002 on board the japanese jigger “Shinko Maru N° 3” under a joint research programme approved by Japan and Argentina. Size ranges of the squids analyzed were 10-40 cm mantle length (ML) for males and 12-49 cm ML for females. Two groups of squids were identified: smaller and larger than 20 cm ML. The group under 20 cm ML was characterized by the presence of immature squids and a sex ratio of around 1:1 in the whole study area. The squids of more than 20 cm ML included from immature to mature individuals. The mean sizes, proportion of mature individuals and proportion of males within this group increased northwards. Mature individuals were captured north of 39°S. The size and weight at 50% maturity were estimated at 30.48 cm ML and 852.95 g body weight (BW) for males and 42.30 cm ML and 2,287.18 g BW for females. The growth in weight of the reproductive system in both sexes was slow until the onset of maturity (males: 27-32 cm LM; females: 37-45 cm LM). The quantitative indices of maturity based on gravimetric measurements of the reproductive system structures showed that in both sexes the reproductive system total weight (RSW) represented less than 1% of BW by the onset of maturity. Then, the growth of the reproductive system accelerated, with RSW reaching 5% of male BW and 8% of female BW by the end of maturity.