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Keywords:

  • Hawaiian monk seal;
  • Monachus schauinslandi;
  • foraging habitat;
  • CRITTERCAM;
  • endangered species

Abstract

The Hawaiian monk seal (Monachus schauinslandi) is thought to be a foraging generalist, preying on numerous species in diverse habitats of the subtropical Northwestern Hawaiian Islands. At the atoll of French Frigate Shoals, recent evidence of emaciation and low survival in monk seals prompted a search for their specific prey communities and foraging habitat.

A video camera (National Geographic Television's CRITTERCAM) fitted to 24 adult male seals documented benthic and demersal foraging on the deep slopes (50-80 m) of the atoll and neighboring banks. The number of bottom searches for prey was compared by year, time of day, type of bottom, individual seal, and length of bottom time. Analysis of variance identified a significant interaction of seal and bottom type, explaining 65% of the total variance. Seals fed on communities of cryptic fauna (fish and large invertebrates) in transitional “ecotone” regions of low relief where consolidated substrate, rubble, and talus bordered areas of sand. Independent areal surveys of bottom types throughout the atoll and neighboring banks suggest that the type of bottom selected as foraging habitat represents a relatively small percentage of the total benthic area available.