MEPS 284:293-303 (2004)  -  doi:10.3354/meps284293

Availability of deep-water fish to trawling and visual observation from a remotely operated vehicle (ROV)

Verena M. Trenkel1,*, R. I. C. Chris Francis2, Pascal Lorance3, Stéphanie Mahévas1, Marie-Joëlle Rochet1, Dianne M. Tracey2

1Laboratoire MAERHA, IFREMER, Rue de l’Ile d’Yeu, BP 21105, 44311 Nantes Cedex 03, France 2National Institute of Water and Atmospheric Research Ltd, Private Bag 14901, Wellington, New Zealand 3Laboratoire Ressources Halieutiques, Ifremer, BP 70, 29280 Plouzané, France

ABSTRACT: Visual observations were collected using video from a remotely operated vehicle (ROV) for a number of deep-water species on the continental slope of the Bay of Biscay, Northeast Atlantic. Relative trawl availability was defined as the ratio of population density estimates from a scientific bottom-trawl survey to those derived from visual strip transects. Several natural and reaction behaviour variables were explored to explain between-species variation in relative trawl availability. The variable with most explanatory power was spatial dispersion, with aggregating species showing lower relative availability than those that were randomly or uniformly distributed. This variable was also strongly correlated with ROV density estimates (aggregated species had the highest densities). Mean distance off the ground and mean body length of a species were positively related to relative trawl availability. In contrast, the way different species reacted to the ROV did not appear to be correlated with relative trawl availability.

KEY WORDS: Remotely operated vehicle · ROV · Catchability · Spatial distribution · Continental slope

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