From trawl to pots: a bio-economic analysis of gear change
Résumé
Poor selective gears like bottom trawlers are known to induce joint productions ie catch of several categories of fish by targeting one category in particular. Joint productions can be inter-species or intra-species. They can be retained to be sold or discarded most of the time with high mortality rates when caught by trawlers. Joint productions make management more complicated as they make classical solutions known to reduce or negate the effects of negative externalities difficult to apply. In this paper, the bio-economic impact of changing gear to reduce joint productions and so limit the external effects is studied in the case of the Nephrops trawl fishery in the bay of Biscay. The example of the Nephrops pot fishery of Loch Torridon (Scotland) compared to the Nephrops trawl fishery in the bay of Biscay enables to discuss the exploitation conditions leading to the success of an alternative gear. An alternative Nephrops pot métier for the Nephrops trawler fleet is parameterized and the bio-economic implications of a gear changement are analyzed in the case of a normative trawl interdiction and under several economic regulations inciting to gear changement.