- ItemRevisión taxonómica y análisis de los caracteres morfométricos y merísticos de la sardina fueguina, Sprattus fuegensis (Jenyns, 1842) (Pisces, Clupeidae)(Mar del Plata: Instituto Nacional de Investigación y Desarrollo Pesquero (INIDEP), 1982) Cousseau, M.B.This paper is based on the study of 484 specimens collected off three different districts of Santa Cruz (Caleta Olivia, Puerto Deseado and Río Gallegos)and the northern coastal region of Malvinas Islands. The following items have been developed: -a brief description of the clupeoids present in the southern patagonic area where the sardine lives, and a key to their identification; -the updated systematic position of the species and its bibliographical references; -a description of the external morphology; -a statistical analysis of morphometric and meristic character; and geographic distribution and movements. It is possible to presume the existence of two geographically separated groups, one in the coasts off Santa Cruz Province and another around Malvinas Islands.
- ItemEstudio de edad y crecimiento de la sardina fueguina (Sprattus fuegensis) de las costas de la provincia de Santa Cruz e Islas Malvinas(Mar del Plata: Instituto Nacional de Investigación y Desarrollo Pesquero (INIDEP), 1982) Cousseau, M.B.; Gru, D.L.Samples of Sardina fueguina (Sprattus fuegensis) were taken during research cruises carried out in 1974 and 1978. Length and age frequency distributions were analyzed, and von Bertalanffy growth parameters were calculated for the coastal waters of two geographical regions: Province of Santa Cruz and northern part of Malvinas Islands. Lenght and weight growth curves have been calculated for each region and each year. Marked differences have been found between gowth parameters of both regions, and the calculated values showed a good fit with the observed ones. According to these results, it is possible to assume that the sardines of both regions constitute two different populations. However, more information on the total distribution of the species will have to be obtained in order to confirm the present observations.
- ItemObservaciones sobre embriones de larvas y juveniles de la pescadilla (Cynoscion striatus)(Mar del Plata: Instituto Nacional de Investigación y Desarrollo Pesquero (INIDEP), 1982) de Ciechomski, J.D.; Cassia, M.C.Observations on the embrionic and larval development of Cynoscion striatus are presented. The description are made on the basis of material obtained by artificial fertilization. Eggs are pelagic, spherical, 700-840µ in diameter and with single oil globule of 210µ-240µ. The yolk is homogeneous and the chorion has smooth surface. The embryonic development is short and at temperatures of 19°-20°C hatching takes place, 34-36 hours after the fertilization. The larvae at hatching are small, about 2 mm in length and not advanced in their development. The mouth is not functional and the anus is not open. The oil globule is situated in the posterior part of the yolk sac; the position of the anus is close to the posterior end of the yolk sac and the digestice tract forms a straight angle with the anus. The dody and the oil globule are pigmented. The juveniles have a rather deep form of the head and of the body and have their charasteristic pigmentation pattern. The preoperculum is provided with strong spines which disappear entirely in larger specimens.
- ItemDistribución y estructura poblacional de la polaca (Micromesistius australis)(Mar del Plata: Instituto Nacional de Investigación y Desarrollo Pesquero (INIDEP), 1982) Perrotta, R.G.The polaca (Micromesistius australis)is a typical fish from the cold Malvinas current (temperatures between 3° and 10°C). The species is found in depths between 90 and 800 m and in latitudes from 37°40' to 50° S during winter and spring and from 42°S to 55°S during summer time, over the patagonian shelf and Burdwood Bank. One part of the stock reaches the southern region of the Scotia Sea, the western South Georgias and eastern South Shetland Islands. The dominant food species are Euphausia spp. The polaca is mainly a carcinophagous fish and may be found in a 3-4 trophic level, being one of the main food sources for primary and secondary ichthyophagous fishes.
- ItemConsideraciones sobre el crecimiento de la caballa (Scomber japonicus marplatensis) durante su primer año de vida(Mar del Plata: Instituto Nacional de Investigación y Desarrollo Pesquero (INIDEP), 1982) Sánchez, R.P.Through the analysis of the morphological changes ocurring in the process of growth, it was possible to identify three stages (primary juvenile: 25-75 mm; secondary juvenile: 76-160 mm; and juvenile preadult: 161-250 mm) during the first year of the species life. Regression equations for the different relations studied: body weight/body lenght, body surface/body lenght, body surface/body weight, and metabolic rate/body lenght, have been calculated for each stage. The variation of the number of gill rakers, mean distance between adjacent rakers and mean values of gill rakers lenght in reference to body growth was studied, and the relation between filtering area and body length was established.