The role of infaunal and epibenthic scavengers in the decomposition of fisheries’ discards

Master Thesis subject (30 ECTS)
Beam trawl fisheries catch a wide variety of fish species and benthic invertebrates. The catches are sorted on-board and subsequently returned to the sea or discarded. While we know that discarded fish is eaten by a number of seabirds, there is very limited knowledge on the fate of a discarded fish, once it arrives at the sea floor. With the introduction of a new European legislation, the Landing Obligation, European fisheries managers envisage the elimination of discards of quota-regulated fish species. Several thousands of tonnes of discards will be extracted from the sea and brought to land. The new legislation will reduce the feeding opportunities of a vast range of benthic scavengers, assumed to feed on discarded fish on the sea floor. This could result in possible knock-on effects on competing scavenger populations, and requires understanding the decomposition of fisheries’ discards by various scavengers. This thesis will investigate the role of infaunal and epibenthic scavengers in the decomposition of discarded plaice, a quota-regulated species that dominates the beam trawl discards. A representative sample of infaunal benthic communities will be taken on-board the Research Vessel ‘Simon Stevin’ using Van Veen grabs. Key scavenger species of epibenthic communities will be selected and collected from at-sea trials using beam trawling. The infaunal benthic community and the key scavengers of epibenthic communities will be brought to the lab to set up a mesocosm experiment. This experiment is designed to investigate simultaneously (1) the effect of different faunal groups (scavengers versus non-scavenging infauna) on the decomposition process of the discarded fish, and (2) the effect of the discarded fish on the infauna.
Number of students: 
academic year: 
contact person first name: 
Jochen Depestele
Other people involved: 
Ulrike Braeckman ( Jan Vanaverbeke ( or
Reference Number: RP-39462