Revista de Investigación y Desarrollo Pesquero 2016 Nro 28

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    Biology and fishery of long tail hake (Macruronus magellanicus) in the Southwest Atlantic Ocean
    (Instituto Nacional de Investigación y Desarrollo Pesquero, 2016) Giussi, Analía R.; Zavatteri, Anabela; Di Marco, Emiliano; Gorini, Federico L.; Bernardele, Juan C.; Marí, Noemí R.
    Long tail hake is one of the most important finfish resources in the Southwest Atlantic Ocean (SAO). This demersal-pelagic fish is widely distributed from 35° S to 56° S between 50 and 800 m depth. In the Patagonian region the species is found on the shelf, associated with three different water masses: Coastal, Shelf and Malvinas Waters, while north of 45° S it is related to the shelf break, following the Malvinas waters. A separate small stock, evident because of its different growth patterns, occurs inside San Matías Gulf. There is no strong difference in growth patterns between sexes, however females are larger than males, principally after the first maturity that occurs at 3 years old. Maximum age observed was 16 years old, but fish older than 12 years are scarce in the population. The dietary composition changes during the life cycle, juveniles are mainly microphagous and adults incorporate larger preys of several invertebrates and vertebrates taxa. Principal food items are zooplankton species; the most abundant are hyperiid amphipods and euphausiids. Fish and cephalopods are secondary prey. Few fish species predate on long tail hake: Southern hake (Merluccius australis), spiny dogfish (Squalus acanthias), and Argentine hake (M. hubbsi). Cannibalism is not reported in long tail hake. Spawning areas have not been detected yet but some signals in somatic conditions allow inferring that this process may occur during spring. A systematic series of summer demersal standard swept area trawl surveys has been conducted since 1992 to assess the population, suggesting that maximum long tail hake biomass was more than 2 million tonnes in the mid 1990’s. Those results were employed as an index of abundance in the annual stock assessment to establish the Total Allowable Catch, but neither environmental variables nor economic effects have been considered yet. Fishing activities began during the mid 1970’s when yields were not significant, but beginning in the 1980’s several fleets targeted long tail hake, increasing catches up to 168,000 t. Products are exported to Europe, Asia and South America.
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    Biology and fishery of the Southern hake (Merluccius australis) in the Southwest Atlantic Ocean
    (Instituto Nacional de Investigación y Desarrollo Pesquero, 2016) Giussi, Analía R.; Gorini, Federico L.; Di Marco, Emiliano; Zavatteri, Anabela; Marí, Noemí R.
    Southern hake (Merluccius australis) is distributed mainly south of 50° S around South America, occurring in cold temperate waters of subantarctic origin. In the Southwest Atlantic Ocean (SAO) only adults are abundant. This species is icththyophagous and malacophagous, feeding mainly on long tail hake (Macruronus magellanicus) and several cephalopods (Illex argentinus, Onykia ingens, Doryteuthis gahi). Age and growth studies show significant sexual differences; females grow to a larger size than males. In recent years, the highest biomasses, estimated from trawl surveys using the swept area method, are about 10,000 t. Fish 4 to 8 years old usually dominate commercial landings. Only a few factory trawler vessels have southern hake as a target species. They operate over the main fishing grounds located near Tierra del Fuego and at the eastern mouth of the Beagle Channel. Average annual landings are about 5,000 t.
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    Biology and fishery of the Argentine hake (Merluccius hubbsi)
    (Instituto Nacional de Investigación y Desarrollo Pesquero, 2016) Irusta, Gabriela; Macchi, Gustavo J.; Louge, Elena; Rodrigues, Karina A.; D'Atri, Luciana L.; Villarino, María F.; Santos, Betina A.; Simonazzi, Mario
    Argentine hake (Merluccius hubbsi) is a demersal, eurythermic and euryhaline species associated to subantarctic waters of the continental shelf and slope. The species, considered the main fishery resource of Argentina that in 2011 reached the maximum catch and export levels, distributes from Southern Brazil to 55° S in a 50-400 m depth range. The three stocks identified, located between 34° S-41° S, south of said latitude and in the San Matías Gulf, show differences as regards reproduction and nursery areas and time, meristic and morphometric characters, abundance level and growth parameters. At the Instituto Nacional de Investigación y Desarrollo Pesquero (INIDEP) annual assessments of the exploitation status of the stocks north and south of 41° S are carried out and management recommendations made. In this chapter, the biology, fishery characteristics, population abundance and structure and management recommendations for the two main Argentine hake stocks are described.