ABStrACt. the annual migration of bowhead whales (Balaena mysticetus) past Barrow, Alaska, has provided subsistence hunting to Iñupiat for centuries. Bowheads recurrently feed on aggregations of zooplankton prey near Barrow in autumn. the mechanisms that form these aggregations, and the associations between whales and oceanography, were investigated using field sampling, retrospective analysis, and traditional knowledge interviews. Oceanographic and aerial surveys were conducted near Barrow during August and September in 2005 and 2006. multiple water masses were observed, and close coupling between water mass type and biological characteristics was noted. Short-term variability in hydrography was associated with changes in wind speed and direction that profoundly affected plankton taxonomic composition. Aggregations of ca. 50 -100 bowhead whales were observed in early September of both years at locations consistent with traditional knowledge. retrospective analyses of records for 1984 -2004 also showed that annual aggregations of whales near Barrow were associated with wind speed and direction. euphausiids and copepods appear to be upwelled onto the Beaufort Sea shelf during e or Se winds. A favorable feeding environment is produced when these plankton are retained and concentrated on the shelf by the prevailing westward Beaufort Sea shelf currents that converge with the Alaska Coastal Current flowing to the northeast along the eastern edge of Barrow Canyon. hydrographie était liée à des changements relatifs à la vitesse et à l'orientation du vent qui avaient de fortes incidences sur la composition taxonomique du plancton. Des agrégations d'environ 50 à 100 baleines boréales ont été observées au début septembre des deux années à des emplacements cadrant avec les connaissances traditionnelles. les analyses rétrospectives des données recueillies de 1984 à 2004 ont également montré que les agrégations annuelles de baleines boréales près de Barrow étaient liées à la vitesse et à l'orientation du vent. les euphausias et les copépodes semblaient remonter vers le plateau de la mer de Beaufort lorsque les vents étaient de l'est ou du sud-est. un milieu alimentaire favorable est créé lorsque le plancton est retenu et concentré sur le plateau par les courants de direction ouest du plateau de la mer de Beaufort qui convergent avec le courant côtier de l'Alaska s'écoulant vers le nord-est le long de la rive est du canyon de Barrow.
[1] Satellite and hydrographic observations of oceanographic conditions in the northwestern Gulf of Alaska indicate that anticyclonic eddies propagating adjacent to the continental shelf alter the structure of the shelf break front and, in doing so, influence the shelf-slope exchange of biota and water mass properties. Eddies typically form in the northern Gulf of Alaska during fall and winter and propagate southwestward within an $200 km wide corridor along and above the continental slope. Eddy activity within this corridor diminishes in the downstream direction. The trajectories of faster propagating (>4 km/day) eddies tend to lie closer to the shelf break than do the trajectories of slower propagating ($1.5 km/day) eddies. The interaction between azimuthal eddy currents and the shelf break frontal jet (1) establishes an upwelling zone, associated with the leading flank of the eddy, that strengthens cross-slope gradients, (2) weakens cross-slope gradients and promotes shelf-slope exchange where the eddy is adjacent to the shelf, and (3) reestablishes a weak upwelling zone associated with the trailing flank of the eddy.
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