Advances in Fishing Power: A Study Spanning 50 Years

Historical relative stock biomass abundance trends for a selected group of demersal species were analyzed considering the technological development of the fishing industry. Official records on landings from the Greek bottom trawl fishery during the past five decades were used as an example. A number of demersal stocks were found to decline at a faster pace than previously believed, while others giving the impression of rapid growth should be considered at a stable status. Using available research survey biomass indices, for the most recent period, a more realistic level of increasing fishing power for the commercial bottom trawl fishery was estimated. The present findings suggest that measuring nominal effort in conventional terms (days at sea, engine capacity, gross tonnage) may yield estimates far from the effective effort exerted by the fleet, which may further be unnoticeably escalating. Since fisheries management in the Mediterranean is predominantly effort-based, accounting for changes in fishing effort seems more decisive than in marine regions, where fisheries are managed by means of landing quotas.