The collapse of the scallop Euvola ziczac (Linnaeus, 1758) (Bivalvia: Pectinidae) fishery in Brazil: changes in distribution and relative abundance after 23 years of exploitation

Abstract

In Brazil, an industrial trawling fishery directed to Euvola ziczac started in 1973 and collapsed after 1980, when scallop landings reached 8,800 t. Since 1995 E. ziczac landings have not surpassed a few hundred kilograms. Based on surveys carried out in 1974-1975 and in 1995-1996, this work assesses temporal changes occurred in scallop distribution and relative abundance patterns and analyzes the current stock situation under the present management regimes applied to the local demersal trawling fishery. In the 1970's E. ziczac was concentrated in a main bed extending from southern São Paulo to northern Santa Catarina States and between 30 and 50 m depth. This pattern changed dramatically during the 1990's, when only two very small and low-density concentrations were found in the region. Cumulative effects of reducing areas and density within the remnant concentrations produced a reduction in the stock biomass of 98%. Management of the local double rig trawler fishery has always focused on its first main target, the shrimps Farfantepenaeus paulensis and F. brasiliensis. Additional measures have not been implemented, even after substantial part of the fleet has directed its effort to alternative shelf and slope resources. The collapse of the Brazilian scallop fishery provides a striking example of irreversible damage caused by uncontrolled fishing redirection allocated to other resources, demonstrating the need of changes in the Brazilian demersal fishery management model.