Seabird Research

Coordinator

Prof. Peter Ryan

Research Team

Dr Timothée Cook (PFIAO), Dr Rob Crawford (Marine and Coastal Management), Dr John Croxall (British Antarctic Survey, Cambridge, UK), Mr John Cooper (Avian Demography Unit, UCT) Dr Marienne de Villiers (Avian Demography Unit, UCT), Mr Benedict Dundee (Department of Zoology, UCT) Dr David Grémillet (CNRS, Strasbourg, France), Dr Geoff Hilton (Royal Society for the Protection of Birds, UK), Dr Deon Nel (WWF-SA), Dr Colleen O'Ryan (Molecular and Cell Biology Department, UCT), Ms Samantha Petersen (WWF-SA), Dr Mareile Techow (PFIAO, UCT), Dr Ross Wanless (PFIAO), Mr Barry Watkins (Marine and Coastal Management).

Projects

• The demographic impact of longline bycatches of Wandering Albatrosses on the population breeding at Marion Island
• What causes the male bias among seabird bycatch in the fishery for Patagonian Toothfish?
• Factors determining seabird bycatch rate on longlines, and the efficacy of mitigation measures

The demographic impact of longline bycatches of Wandering Albatrosses on the population breeding at Marion Island

Research Team: Deon Nel, Peter Ryan

This project, funded by the Department of Environment Affairs and Tourism through the South African National Antarctic Programme, examines the demographic impacts of longline fishing mortality. It builds on studies of colonies of individually-marked Wandering Albatrosses at Marion Island since the early 1980s. Significant numbers of Wandering Albatrosses have been killed by tuna longline fisheries for at least the past 30 years, and since 1997 they have been affected by fishing for Patagonian Toothfish around the Prince Edward Islands. Studies of the birds’ foraging ranges, diet and the genetic structure of the islands’ populations will provide useful input to fisheries management options. One of the key products will be a demographic model of the Wandering Albatross population at the Prince Edward Islands.

What causes the male bias among seabird bycatch in the fishery for Patagonian Toothfish?

Research Team: Deon Nel, Peter Ryan

Approximately 80% of adult birds killed on longlines fishing for Patagonian Toothfish at the Prince Edward Islands are male. Limited data from the South Georgia fishery suggests the same bias occurs there. 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.

Factors determining seabird bycatch rate on longlines, and the efficacy of mitigation measures

Research Team: Peter Ryan, Deon Nel

Fisheries observers record the numbers of birds killed on each longline set in the toothfish fishery around the Prince Edward Islands. 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.