The current European Union fisheries policy encourages improving
handling practices to increase the survival of discards. Trawling on the
Mediterranean upper slope often generates over 30% of discards of the
total catch. Among other species, Nephrops norvegicus juveniles are abundantly returned to the sea, sometimes exceeding 40% of discarded biomass. N. norvegicus discard survival probability has been recently shown to be related to
vitality on board and to vary seasonally, being especially low during
the summer (0.06). Environmental characteristics (especially, high
on-deck temperature in summer) make it necessary to improve vitality on
board in order to increase discard survival. We therefore tested new
discard handling methodologies for a Mediterranean mixed trawl fishery,
with N. norvegicus as the target species. The results showed a
survival rate on board higher than 0.8 resulting from vitality status
improvements achieved by immersing N. norvegicus in cooled
seawater on board during the catch selection and discard time. The
implementation of this method would make an important contribution to
more sustainable Mediterranean trawl fisheries. |