Black-browed albatrosses, international fisheries and the Patagonian Shelf

Albatrosses have among the most remarkable travelling capacities of any extant animal. However, previous studies regarding their movements at sea have mainly focused on breeding birds commuting between the nest site and offshore feeding grounds. In this study, we compare the move ment patterns and at-sea activity of breeding and inter-breeding black-browed albatrosses Diomedea melanophris from the Falkland Islands. Data were recorded via global location and activity sensors for 26 incubating birds (during single foraging trips lasting 6.8 d on average) and 6 inter-breeding individuals (during non-stop offshore journeys of 127.5 d on average). Our results showed that foraging black-browed albatrosses utilise vast offshore areas (the average foraging area was 102000 +/- 132 000 km(2) by incubating birds and 1552 000 +/- 970 000 km(2) by inter-breeding birds). However, mean foraging range was similar in both groups (691 +/- 330 km and 680 +/- 192 km by incubating and interbreeding birds, respectively) as were their core foraging areas and their at-sea activity patterns. Our results thus indicate that black-browed albatrosses from the Falkland Islands, which represent the largest albatross population world-wide (ca 800 000 individuals), mainly rely on marine resources avail able within the Patagonian Shelf area. Although this highly productive continental shelf is the largest of the Southern Hemisphere, rapid development of industrial fisheries currently results in the removal of over 1.4 million tonnes of fish and squid per year in this zone. As our data also show significant spatio-temporal overlap between human and albatross fishing activities within the Patagonian Shelf, we anticipate major detrimental effects on the albatross population in terms of competition for food and additional mortality caused by bird bycatch.