- ItemGrenadiers (Pisces, Macrouridae) of the southwest Atlantic ocean: biologic and fishery aspects(Mar del Plata : Instituto Nacional de Investigación y Desarrollo Pesquero (INIDEP), 2010) Giussi, A.R.; Sánchez, F.; Wohler, O.C.; Bernardele, J.C.Several grenadier species distribute in the SW Atlantic Ocean. Macrourus carinatus and Caelorinchus fasciatus are more frequently identified in commercial catches and during research cruises. Those benthopelagic fishes, related to subantarctic waters, inhabit at depths beyond 200 m and in high seas, between 36º S-59º S. During the surveys carried out on board of Argentinean research vessels, M. carinatus was present in 4% of the trawls performed. The highest densities (>17 t nm-2), obtained between 360-380 m depth, at 39º S, decreased significantly southwards. C. fasciatus was caught in 6% of the total trawls and the highest densities (15-35 t nm-2) were found at depths beyond 200 m, south of 52º S. Due to the difficulty encountered to identify them, in fishing statistics they are grouped as ‘Grenadiers’. Nevertheless, in many cases, the correct identification by scientific observers on board of commercial vessels provides useful information to support the data gathered. Grenadiers are caught as by-catch in important fisheries that have the main fishing grounds south of 52º S. Historically, different countries participated in the fishery that shows two evolution periods. In the first, exploitation carried out mainly by vessels from the former USSR reached a maximum of 31,000 t in 1984. In the second, the Argentine fleet caught up to 10,000 t in 2000. At present, freezer and factory trawlers obtain 88% of the catches and longliners 10% of the total.
- ItemEl ecosistema de la plataforma patagónica austral durante el verano, marzo-abril 2000. Estimación de la biomasa fitoplanctónica a partir de la distribución de clorofila a(Mar del Plata : Instituto Nacional de Investigación y Desarrollo Pesquero (INIDEP), 2010) Reta, R.The distribution of chlorophyll-a concentration in the austral Patagonian (SW Atlantic Ocean) shelf between 47º S-54º S with in situ data collected in March-April 2000 is analyzed. Data derived from Niskin samples and continuous in situ fluorometry. Two areas with high chlorophyll values (~- 1.6 mg m-3) on the central shelf corresponding to the area between isolines 100-150 m depth and near the coastal region off Bahía Grande south of the Santa Cruz river (Argentina) were identified. Minimum values (~, 0.5 mg m-3) were found in the coastal zone close to the 50 m isobath and to the southern region of the Patagonian shelf. Fluorescence: chlorophyll-a concentration ratios were more variable at sea surface than at different depths of the water column. The possible causes for the vertical distribution of chlorophyll-a are analyzed.
- ItemAlimentación del calamar Illex argentinus en la región patagónica durante el verano de los años 2006, 2007 y 2008(Mar del Plata : Instituto Nacional de Investigación y Desarrollo Pesquero (INIDEP), 2010) Ivanovic, M.L.The information gathered during four research cruises carried out in January and February of 2006, 2007 and 2008 allowed to analyze the summer feeding pattern of Illex argentinus squid in the shelf and slope of the Patagonian region (43º S-51º S), SW Atlantic Ocean. Intake, that took place during daytime, had its peak as of midday. Of the preys eaten amphipods and euphausiids, two groups of zooplanktonic organisms, represented 71-99% of the diet. The most frequent preys found in three of the four cruises corresponded to amphipods, represented by a single species, the hyperiid Themisto gaudichaudii, that accounted for over 50% of the food consumed. When depth of the catching area was beyond 100 m an increase in consumption of squid and fish by specimens above 20 cm ML was observed. No clear trends were found between the type of prey consumed and the time of catches or the degree of stomach repletion of the predator. The diet, of low diversity, showed that 56-62% of the squids studied fed on a single type of prey.
- ItemEstimación de la edad y el crecimiento de la merluza austral Merluccius australis (Hutton, 1872) del Mar Argentino(Mar del Plata : Instituto Nacional de Investigación y Desarrollo Pesquero (INIDEP), 2010) Gorini, F.L.; Abachian, Viviana; Giussi, A.R.Southern hake (Merluccius australis) age and growth were estimated using sagittae otoliths obtained in research cruises and observers programs in the Argentine Sea (SW Atlantic). The only annual growth ring observed, formed by two bands, one hyaline and another opaque, corresponded to winter and summer growth, respectively. According to the analysis of otoliths edge, birthday was established on 1st July. Within the age range observed, that comprised 3-18 year old specimens, age groups 7, 8 and 9 were the most frequently identified in both sexes. Growth parameters estimates showed significant differences between them.
- ItemLarval and juvenile growth of two Patagonian small pelagic fishes: Engraulis anchoita and Sprattus fuegensis(Mar del Plata : Instituto Nacional de Investigación y Desarrollo Pesquero (INIDEP), 2010) Brown, D.R.; Sánchez, R.P.Patagonian anchovy (Engraulis anchoita) and sprat (Sprattus fuegensis) constitute the two most important pelagic resources of the Argentine Patagonian shelf (SW Atlantic). Age and growth parameters of larvae and juveniles of both species were determined analyzing otoliths daily increments. A total of 404 anchovies (4.1-33 mm SL) and 157 sprats (5-41 mm SL) were analyzed. The Laird-Gompertz growth model was fitted to the length-at-age data of anchovies: L(t) = 4.2 exp (2.28 (1-(-0.034 t))). The parameters of the model were: L: 41.06 mm; the inflection point: 15.11 mm and 27 days; and the maximum growth rate: 0.51 mm day-1. The length-at-age data of sprat larvae and juveniles were represented in two linear models: L(t) = 0.32 t + 7.6; and L(t) = 0.22 t + 6.6. Slopes represented mean growth rates, 0.32 and 0.22 mm day-1 for larvae and juveniles, respectively. Variations in length-at-age between years were determined through the analysis of individual growth trajectories. Variations were found in sprats, not in anchovies.