FORAGING OF JUVENILE MONK SEALS AT FRENCH FRIGATE SHOALS, HAWAII |
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| Authors: | Frank A Parrish Gregory J Marshall CharlesL Littnan Mike Heithaus Suzanne Canja Brenda Becker Robert Braun George A Antoneijs |
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| Institution: | Pacific Islands Fisheries Science Center, NOAA Fisheries 2570 Dole Street, Honolulu, Hawaii 96822–2396, U.S.A. E-mail:;National Geographic Television, 1145 17th Street N.W., Washington, DC 20036–4688, U.S.A.;Pacific Islands Fisheries Science Center, NOAA Fisheries 2570 Dole Street, Honolulu, Hawaii 96822–2396, U.S.A.;Florida International University, North Miami, Florida 33181, U.S.A.;Aquatic Farms, 2570 Dole Street, Honolulu, Hawaii 96822–2396, U.S.A.;Pacific Islands Fisheries Science Center, NOAA Fisheries 2570 Dole Street, Honolulu, Hawaii 96822–2396, U.S.A.;Joint Institute for Marine and Atmospheric Research, University of Hawaii, 2570 Dole Street, Honolulu, Hawaii 96822–2396, U.S.A.;Pacific Islands Fisheries Science Center, NOAA Fisheries 2570 Dole Street, Honolulu, Hawaii 96822–2396, U.S.A. |
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| Abstract: | Emaciation and poor survivorship of juvenile Hawaiian monk seals at French Frigate Shoals atoll prompted a study of their foraging, using video camera technology ( crittercam ). Nine juveniles between the ages of 1 and 3 yr (six males, three females) were fitted with crittercam to identify their foraging habitat and feeding behavior. All feeding was directed at small (≤ 10 cm), cryptic, benthic prey. Older seals (ages 2 and 3), varied in their foraging intensity with most of their attention directed at shallow atoll depths (10–30 m). In contrast, the three yearlings focused all their feeding in the sand fields (50–100 m) on the atoll's outer slope. Bottom trawls were used to assess the prey abundance of the sand habitat and found 70% of the numerical catch was flounder ( Bothidae ). Extrapolating the yearlings' prey capture rate (0.13/min, derived from the crittercam video) over their total bottom time yielded an estimated 1–1.3 kg/day of flounder. The mean size of flounder (5 ± 1.7 cm) caught in the bottom trawls was close to the size at which larval flounder settle from the plankton (3 cm), suggesting that localized changes in oceanography could directly impact the seals' prey supply. Extensive use of sand communities by young seals may be the strongest link yet identified between juvenile survivorship and oceanographic dynamics. |
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| Keywords: | Hawaiian monk seal Monachus schauinslandi forage habitat crittercam endangered species sand communities |
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