This project compares the diets and foraging strategies of affected seabird species to assess whether there are any clear sex-linked differences which could account for the differential mortality. It will also model the implications of sex-biased mortality on seabird demography. Skippers on hake longline vessels also are required to report bird bycatches. Both fisheries also report the time and conditions prevailing when each set took place. This project uses generalised linear modelling to assess the contributions of several interacting factors in determining seabird bycatches with a view to setting regulations to minimise bycatch.
Specific experimentation is underway using a sub-surface setting device.
This behaviour predisposes them to be caught on baited hooks used in longline fisheries. There are many anecdotal reports of feeding hierarchies among scavenging seabirds, but few studies have been conducted on this phenomenon. We shall experimentally manipulate the amounts and nature of discards to investigate the influence these factors have on seabird assemblages and their foraging hierarchies. This project should provide useful insights into the differential bycatch rates of seabirds in various longline fisheries, and provide guidelines for the most appropriate way to discard fishery wastes. The impact of the hake Merluccius spp.