SURVIVAL OF FIVE SPECIES OF CAPTIVE MARINE MAMMALS

Authors

  • Robert J. Small,

    1. National Marine Mammal Laboratory, Alaska Fisheries Science Center, National Marine Fisheries Service, 7600 Sand Point Way NE, Seattle, Washington 98115, U.S.A.
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  • Douglas P. Demaster

    1. National Marine Mammal Laboratory, Alaska Fisheries Science Center, National Marine Fisheries Service, 7600 Sand Point Way NE, Seattle, Washington 98115, U.S.A.
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Abstract

Survival in captivity was calculated for 1,707 bottlenose dolphins (BD), 72 killer whales (KW), 73 white whales (WW), 3,090 California sea lions (CSL), and 47 Steller sea lions (SSL) based on data in the Marine Mammal Inventory Report (MMIR) of the NMFS. Mean annual survival rates (ASRs) between 1988 and 1992 were 0.951, 0.937, and 0.954 for BD, KW, and WW, respectively, and 0.952 and 0.969 for CSL and SSL, respectively. These estimates represent significant increases in survival for both BD and CSL over the last 5 yr. Using all of the MMIR data (1940–1992), the ASR of BD calves (< 1 yr of age) was significantly less than the ASR of non-calves (0.666 vs.948, 0.001). Similarly, the ASR of CSL pups (< 1 yr of age) was significantly less than survival of non-pups (0.858 vs.962, 0.001). Survival of captive-born CSL was significantly higher than those born in the wild (0.962 vs.945, 0.003), but the difference was not significantly different for BD (0.948 vs.944, 0.60). For non-calf BD and KW, captive animals survived at a slightly lower rate (BD 0.944 vs.961, = 0.07; KW 0.938 vs.976, 0,001) than animals in the wild (BD: Wells and Scott 1990, KW: Olesiuk 1990). Survival of captive non-pup SSL was slightly higher (0.968 vs.930) than animals in the wild (York 1994, life-table analyses). Survival rates were significantly different among institutions for BD calves and non-calves, CSL pups and non-pups, and SSL non-pups.

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