Marine mammal and seabird bycatch in California gillnet fisheries in 2010
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Marine mammal and seabird bycatch in California gillnet fisheries in 2010

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  • Description:
    Observed and estimated bycatch of marine mammals and seabirds is reported for the California swordfish and thresher shark drift gillnet fishery and the California halibut and white seabass set gillnet fishery from fishery observer data collected in 2010. Estimates of bycatch are generated using ratio estimation methods. There was no observed bycatch of sea turtles in California fisheries in 2010. Observations in the swordfish and thresher shark fishery include 59 sets during 12 fishing trips, from an estimated 492 sets fished by all vessels (11.9% observer coverage). Observed bycatch included three short-beaked common dolphin (Delphinus delphis), one long-beaked common dolphin (Delphinus capensis), one northern right whale dolphin (Lissodelphis borealis), one common bottlenose dolphin (Tursiops truncatus) and two sperm whales (Physeter macrocephalus). All marine mammals were dead upon retrieval, with the exception of one sperm whale that was released seriously injured with trailing gear. Estimated bycatch is 25 (CV=0.64) short-beaked common dolphins, 8 (CV=1.00) long-beaked common dolphins, 8 (CV=0.98) northern right whale dolphins, 8 (CV=0.96) bottlenose dolphins, and 16 (CV=0.95) sperm whales. Observations in the halibut and white seabass fishery include 216 sets during 57 fishing trips, from an estimated 1,724 sets fished by all vessels (12.5% observer coverage). Observed bycatch included one long-beaked common dolphin (Delphinus capensis), 25 California sea lions (Zalophus californianus), three harbor seals (Phoca vitulina), two common murres (Uria aalge), one double-crested cormorant (Phalacrocorax auritus), one Brandt's cormorant (Phalacrocorax penicillatus), one unidentified gull (family Laridae) and three unidentified birds. Estimated bycatch is 7 (CV=1.07) long-beaked common dolphin, 199 (CV=0.30) California sea lions, 23 (CV=0.59) harbor seals, 15 (CV=1.05) common murres, 7 (CV=1.15) double-crested cormorants, 7 (CV=1.13) Brandt's cormorants, 7 (CV=1.00) unidentified gulls, and 23 (CV=1.03) unidentified birds. Other fisheries observed in 2010 include the CA yellowtail, barracuda, and white seabass drift gillnet fishery (11 sets, approximately 5% observer coverage) and the CA pelagic longline fishery (at 100% observer coverage) that operates outside of the U.S. Exclusive Economic Zone. There was no marine mammal, sea turtle, or seabird bycatch observed in either fishery in 2010. Data confidentiality regulations preclude the reporting of set data for the California pelagic longline fishery, as only one vessel was active.
  • Content Notes:
    James V. Carretta and Lyle Enriquez.

    "February 2012."

    System requirements: Adobe Acrobat Reader.

    Includes bibliographical references (pages 6-7).

  • Rights Information:
    Public Domain
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