Depredation by antarctic fur seals (Arctocephalus gazella), sperm whales (Physeter macrocephalus) and orcas (Orcinus orca) were studied in a Patagonian toothfish (Dissostichus eleginoides) fishery operating around South Georgia. While sperm whales come in contact with about one third of longlines (averaged over 1997 and 2012), depredation events from this species were considered insignificant. Orcas interacted with only 5% (averaged over 1997 and 2012) of longlines, but can remove over half the catch during an interaction. Interactions with orcas are spatially limited to migration routes; however, fishing is concentrated in these areas during migrations times. Interactions with fur seals were the most frequent until 2009, averaging just under 9% from 1997-2012. The catch-per-unit-effort of toothfish was higher when no mammals were observed near longlines.
Year
Journal/Publisher Name
PLoS ONE
Volume (Issue #)
10
Page #s
14
Contact information
marta.soffker@cefas.co.uk
Summary
Field Studies
The impact of predation by marine mammals on Patagonian toothfish longline fisheries
Study Type
Field study in the wild
Location
South Georgia
Target catch
Patagonian toothfish
Effect on bycatch species
Sperm whales interacted with longlines 25% of the time; orcas interacted only 5% of the time could remove half of the catch; fur seal interactions have declined since 2009
Effect on target catch
Catch rates were lower when marine mammals were present
Bycatch species
Fishing Gear