Summer abundance of pack ice seals in the vicinity of Primavera Station, Danco Coast, Western Antarctic Peninsula

NEGRETE JAVIER; CARLINI PEDRO; LEONARDI MARÍA SOLEDAD; BOBINAC MAGALÍ; GUERRERO ALICIA; ROGERS TRACEY. L

Leuven

Simposio; XIITH SCAR BIOLOGY SYMPOSIUM; 2017

SCAR

Antarctic pack ice seals are top predators that depend of sea ice to breed, moult, and rest. Therefore, the knowledge of their abundance and trends may be useful to detect changes in the Southern Ocean environment. During 4 consecutive austral summers seasons (January ?February) we counted pack ice seals observed in ice floes. Counts were made from zodiac boats between 10 am and 16 pm (local time) in an area of 14 nautical mile2 in the vicinity of the Argentinean station Primavera. The study area includes three coves (Cierva, Escondida y Santucci Cove) and a series of islands. Climate during summer use to be benevolent providing shelter to seals that hauling out in floes. Except for 2014 season, the most abundant species during the study period (2012-2015) was the leopard seal (Hydrurga leptonux) with a mean annual density that range from 0.7 to 1.3 seals per n.m-2. Crabeater seal´s (Lobodon carcinophaga) mean annual density range from 0.1 to 3.4 seals per n.m-2 while Weddell seals (Leptonychotes weddelli) density range from 0.2 to 0.4 seals per n.m-2. A negative trend in the number of leopard seals was observed for the study period (F = 7.14 P = 0.01, r2 = 0.37) while the numbers of crabeater seals increased (F = 6.43 P = 0.01, r2 = 0.35). These opposite trends in the abundance of leopard and crabeater seals might reflect competition for resources. Particularly, for animals captured and sampled in this the study area Rogers et al (2014) observed changes in the diet of leopard seals that shifted from eating penguins and seals to a krill based diet. Therefore, it is possible that leopard seals are looking for new areas to moult in order to avoid competition for the same prey with a specialized krill eating species that use to forage in great pods. Considering that crabeater seals are highly mobile species with seasonal migration for foraging, a long time survey could elucidate the trends observed in this short period. Nevertheless, the data presented here is of a great value since represent the first report of seals abundance for the waters surrounding the Antarctic Specially Protected Area N°134 ?Punta Cierva?.