Behaviour of epibenthic scavengers feeding on discarded fish: inter- and intraspecific competition effects

Type: 
Master Thesis subject (30 ECTS)
programme: 
EMBC+
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 epibenthic scavengers in the decomposition of discarded plaice, a quota-regulated species that dominates the beam trawl discards. Epibenthic scavengers and ‘discarded plaice’ will be collected on-board the Research Vessel ‘Simon Stevin’ using a 3-m beam trawl and potentially during sea trials on-board the RV ‘Belgica’. The epibenthic community of the investigated research station (115bis) in the Belgian Part of the North Sea will be characterised using the 3m beam trawl hauls. Key scavenger species will be selected and brought to the lab to set up a mesocosm experiment. Based on experience of the scavenging behaviour of individual epibenthic scavengers and on the densities of the epibenthic community in station 115bis, an experiment will be set up in a flume (large aquarium) that will investigate the scavenging behaviour of one versus many individuals of one species. What is the effect of density on the scavenging behaviour of Common starfish (Asterias rubens) for instance? The scavenging behaviour may be further influenced by competitive interactions between two scavenging species (e.g. Common starfish and velvet swimming crab, Necora puber). As such, this study will investigate the effect of density and competitive interactions on epibenthic feeding behaviour on ‘discarded’ plaice.
prerequisites: 
At least part of the thesis will be conducted in Oostende, because of the availability of lab facilities.
Number of students: 
1
academic year: 
2016-2017
contact person first name: 
Jochen Depestele
Other people involved: 
Ulrike Braeckman (Ulrike.Braeckman@UGent.be) Jan Vanaverbeke (jvanaverbeke@naturalsciences.be)
Reference Number: RP-39671