CETACEAN DISTRIBUTIONS AND OCEANOGRAPHIC FEATURES NEAR THE KERGUELEN PLATEAU

Cetacean surveys were conducted in the austral summer during World Oce an Circulation Experiment hydrolegs 18S and 19S in the southeastern In dian Ocean. The highest density of cetaceans occurred along the southe rn flank of the Kerguelen Plateau and northern edge of the Princess El izabeth Trough, where the distribution of whales coincides with the me an positions of the Southern Front of the Antarctic Circumpolar Curren t (ACC) and southern water mass boundary (Southern Boundary) of the AC C. The topographic steerage of these features of the ACC around the so uthern edge of the Kerguelen Plateau brings shoaled, nutrient-rich Upp er Circumpolar Deep Water (UCDW) to higher latitude than in adjacent b asins. The higher concentrations of cetaceans near the Kerguelen Plate au suggests that whales benefit from a cascade of trophic dynamics ass ociated with the poleward extent of UCDW, the marginal ice edge zone, and the proximity of several oceanographic features: the high latitude penetration and close alignment of the Southern Front and Southern Bo undary of the ACC; the unique poleward extent of the Southern Boundary as it is topographically steered around the plateau; the entrainment of macronutrients into the surface mixed layer near the Southern Bound ary; isopycnal shoaling in cyclonic eddies; the presence of complex ba thymetry; and the advection of a tongue of ice northward along the eas tern side of the plateau. The association between these concurrent oce anographic features and whales suggests that the southeastern edge of the Kerguelen Plateau is a predictably productive foraging location fo r cetaceans and their prey.