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BIBTEX RIS

A comparison of methods for estimating relative abundances in bottom longline fishery surveys

2007; Elsevier BV; Volume: 85; Issue: 1-2 Linguagem: Inglês

10.1016/j.fishres.2007.01.003

1872-6763

Manuel Haimovici, Antônio Olinto Ávila-da-Silva,

Fish Ecology and Management Studies

Longlines lose fishing power with soaking time due to bait losses and hooked fishes. Because logbook records and dockside interviews usually do not include detailed data on fishing power loss, relative densities in commercial fishing are estimated as the number or weight of fishes caught per hook and unit of time. To investigate the influence of the fishing power loss of bottom longlines on relative density estimates, data of 188 standardized hauls of 1000 hooks, baited with squid and soaked for 3 h in average were analyzed. The estimates given by the number of fish caught per 1000-hook-hour (CPUE) were compared to those from the partial removal instantaneous rates (λ) caused by each species, an index that requires detailed information that takes into account the progressive decrease in the number of baited hooks available to fish. It was found that, for relatively short hauls observed in commercial fishing operations in Southern Brazil, the patterns of bathymetric and latitudinal distribution of the three most numerous species in the catch did not differ significantly when calculated in either units. Nevertheless, high initial catch rates resulted in lower correlation between both measures. It was concluded that the analysis of CPUE from bottom longline commercial fishing catches can result in reliable information on the distribution and relative abundance of the target species in the fishery.