INVESTIGADORES
CASAUX Ricardo Jorge
congresos y reuniones científicas
Título:
The CCAMLR Ecosystem Monitoring and Management Working Group
Autor/es:
CASAUX R.; RAMÓN A.
Reunión:
Workshop; CHANGES IN THE DIET OF THE SOUTH GEORGIA SHAG Phalacrocorax georgianus AT THE SOUTH ORKNEY ISLANDS ALONG FOUR CONSECUTIVE YEARS; 2000
Resumen:
The
diet of the South Georgia Shag Phalacrocorax
georgianus at Laurie Island, South Orkney Islands, was studied by the
analysis of 337 pellets (regurgitated casts) collected during the 1995, 1996,
1997 and 1998 breeding seasons. Demersal-benthic fish were by far the main
prey, followed by molluscs (mainly octopods and bivalves) and polychaetes. Harpagifer antarcticus (in 1995 and
1998) and Lepidonotothen nudifrons
(1996 and 1997) were the most frequent preys followed by Gobionotothen gibberifrons or Trematomus
newnesi. Harpagifer antarcticus,
followed by L. nudifrons or T. newnesi, was the most numerous prey
in all of the seasons and predominated in mass in 1995 and 1996, followed by Notothenia coriiceps and L. nudifrons. In 1997 G. gibberifrons and N. coriiceps were the species that most contributed to the diet
whereas N. coriiceps and H. antarcticus did in 1998. Our results
differ from those reported also for the South Orkney Islands in previous
studies. These differences could be due to the use of different diet analysis
methods and to shags-related and/or fisheries-related changes in the food
availability. If assumed that the fisheries carried out in the area affected
the structure and abundance of the fish populations, the comparison of our
results with historical data may be indicating a recovery of G.
gibberifrons in inshore waters around the archipelago.