Rodgveller, Cara J. and Lunsford, Chris R. and Fujioka, Jeffrey T. (2008) Evidence of hook competition in longline surveys. Fishery Bulletin, 106(4), pp. 364-374.
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Catch rates from surveys are used as indices of abundance for many fish species. Relative abundance estimates from surveys with longline gear do not usually account for possible effects of gear saturation, which potentially creates competition among fish for baited hooks and misrepresentations of abundance trends. We examined correlations between catch rates of sablefish (Anoplopoma fimbria) and giant grenadier (Albatrossia pectoralis) and between sablefish and shortraker (Sebastes borealis) and rougheye rockfish (Sebastes aleutianus) from 25 years of longline surveys in Alaska waters for evidence of competition for hooks. Sablefish catch rates were negatively correlated with giant grenadier catch rates in all management areas in Alaskan waters, and sablefish and rockfish were negatively correlated in five of the six areas, indicating that there is likely competition for hooks during longline surveys. Comparative analyses were done for trawl survey catch rates, and no negative correlations were observed, indicating that the negative correlations on the longline surveys are not due to differing habitat preferences or direct competition. Available adjustments for gear saturation may be biased if the probability of capture does not decrease linearly with baited hooks. A better understanding of each fish species’ catch probabilities on longline gear are needed before adjustments for hook competition can be made.
|Title:||Evidence of hook competition in longline surveys|
|Journal or Publication Title:||Fishery Bulletin|
|Page Range:||pp. 364-374|
|Issuing Agency:||United States National Marine Fisheries Service|
|Depositing User:||Patti M. Marraro|
|Date Deposited:||12 Jun 2012 17:55|
|Last Modified:||12 Jun 2012 17:55|
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