Trophic spectrum of southern right whale Eubalaena australis by means of faecal analysis.

MENÉNDEZ, M.C.; BERASATEGUI, A.A.; LINDNER, M.S.; DIODATO, S.L.; FERNÁNDEZ SEVERINI, M.D.; HOFFMEYER, M. S

Buenos Aires

Jornada; VIII Jornadas Multidisciplinarias de la SAB; 2006

Sociedad Argentina de Biología

Eubalaena australis lives in Nuevo Gulf (Chubut) from April to middle of December after a long migration from its feeding areas at high latitudes. It was thought that E. australis did not feed at this breeding zone at all. However, trophic behaviours of whales have been recently observed in both Nuevo and San José Gulfs, especially during the springtime. Also, faeces of whales have been detected from whalewatching ships in the northeastern coasts of Nuevo Gulf. Faeces collected in October 2004 were qualitatively analyzed as part of a large project aimed to evaluate the plankton availability related to whale’s trophic behaviour. Faeces preserved in alcohol 70% were homogenized and three 5 ml-subsamples were taken to identify the strong remains of food items. They were treated with glycerine and methyl blue to improve the viewing of food remains under stereo and optical microscopes. Some of this material belonged to mandibles and coxae of Calanus australis and/or Calanoides carinatus, large Calanidae copepods that live in this zone. Pieces of crustacean segments and antennae were also observed, some of which would probably correspond to euphausiids. In terms of relative abundance, copepod mandibles were the most abundant remains (>70%), non identified tegument parts were abundant (30- 70%) whereas copepod coxae and prosomes were scarce (<30%). These findings, obtained for the first time in Argentina, are a clear evidence of whale-foraging either in this breeding area or previously into the shelf. The foraging on large copepods agrees with that reported for the northern right whale Eubalaena glacialis on Calanus finmarchicus in the North West Atlantic feeding areas.