The delayed mortality of discarded sea bream (Sparus aurata Linnaeus, 1758) in trawl simulation: an experimental appraisal

Abstract

This study aims to bring to light behavioral impairment and the delayed mortality of discards below legal catch rate in a simulated trawl operation. Behavioral impairment of 126 fish in the aftermath of trawling operation was tested in two different methods through observing their reflexes. In the first method, all the fish in the tank was compared with the control groups on account of their responds to different stimulants, while in the second method, reflex measurement was individually carried out. Reflexes from these two processes were taken as the extent of behavioral impairment and a relation with delayed mortality was established. A considerable number of fatalities among those returning to the water came about within 24 hours. There was a proportional connection between behavioral impairment and delayed mortality. However high the behavioral impairment might be, the mortality rate remained at a certain proportion. A considerable number of fish survived under confined medium in the laboratory tanks.