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OALib Journal期刊

ISSN: 2333-9721

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Comparative analysis between gill netting and sport fisher catches in a small patagonic andean lake: its implications for resource evaluation and management
Lippolt,Gustavo E; Vigliano,Pablo H; Alonso,Marcelo F; Macchi,Patricio J; Milano,Daniela; Denegri,María A; García Asorey,Martín;
Ecolog?-a austral , 2011,
Abstract: knowledge of lake fish communities of argentine patagonia has grown in the past 20 years thanks to the use of gill nets. however, national park officials and fisher organizations dislike their use and would prefer the use of recreational fisher catch data. the present paper addresses advantages and disadvantages of using gill nets as compared to fishers. this was accomplished by analysis of gill net and fisher catch data from lake guillelmo, parque nacional nahuel huapi for the period 1997-1999. both sets of data revealed the presence of only two salmonids, brook trout (salvelinus fontinalis) and rainbow trout (oncorhynchus mykiss). however, relative abundances of each species differed between fishing techniques, rainbow trout being dominant according to fisher catches and brook trout according to gill net catches. in addition, differences in size, age and spatial distribution brought about by the highly selective nature of fisher catches were clearly observed. this shows that fisher catch data can only be used to assess existing recreational patagonian lake fisheries in terms of current or historical trends in catch composition, structure and fishing pressure. studies of community composition, structure and processes leading to conservation or recreational fishery management should rely on gill net sampling designs tailored to different ecological and management questions, which can be complemented by fisher catch data.
Composición, distribución y relaciones tróficas de la ictiofauna del río Negro, Patagonia Argentina
Alvear,Pablo A; Rechencq,Magalí; Macchi,Patricio J; Alonso,Marcelo F; Lippolt,Gustavo E; Denegri,María A; Navone,Guillermo; Zattara,Eduardo E; García Asorey,Martín I; Vigliano,Pablo H;
Ecolog?-a austral , 2007,
Abstract: the patagonic ictiogeographic region is characterized by a low species diversity. despite that the negro river is the most important water body in the region, both in terms of the size of its drainage basin and of its socioeconomic importance, its fish fauna has scarcely been studied. the present paper addresses biogeographic and ecological characteristics related to its fish. gill net gangs, electro fishing and beach seine nets were used to sample seasonally five stations along the river. fish fauna composition and distribution were analyzed throughout different ecological indexes. diet composition was also analyzed to establish trophic roles, competition and piscivory. we caught seven native and six exotic species; two of them (corydoras paleatus and cyprinus carpio) represent a widening of their austral distribution. the natives odontesthes hatcheri, percychthis colhuapiensis, p. trucha and jenynsia multidentata were more important in terms of numbers in catches. ecological indexes show that the lower part of the negro river differs from the rest of the river with higher numbers of o. hatchery and j. multidentata. eight trophic groups were found as well as evidence of diet overlapping and considerable piscivory. presence and distribution of fish in the negro river is strongly influenced by introduction by men, either accidentally or intentionally. impacts by introduced species need to be addressed, specially in terms of emerging processes between native and exotic fish, taking into special consideration the negative impacts that the rainbow trout and the carp have already had in different parts of the world.
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