>Life History Introduction l Strandings l Fishery Observer Program l Blubber Steroid Hormones l Frozen Tissue Archive
Fishery Observer Program
Shortbeak common dolphin
Fishery observer programs provide a unique opportunity to collect data about a species from the habitat in which they live. These programs in conjunction with stranding networks have provided most of the data we have about cetacean species living off California and in the eastern tropical Pacific. Fishery observers are trained to collect biological samples from incidentally killed marine mammals. The suite of data collected includes species identification, gender, and total body length, as well as samples of skin for genetics, gonads for reproductive status determination, stomachs for documenting prey, teeth for age, and the skeleton for morphological studies.
Currently, the Southwest Region monitors the drift gillnet and pelagic longline fisheries. We process biological samples collected from marine mammals, cetaceans and pinnipeds, from the driftnet fishery that operates off the California coast. Observers are placed on about 20% of all fishing trips and are instructed to sample marine mammals that are accidentally killed in gillnets. Recently imposed time/area closures to protect turtle species have resulted in reduced incidental marine mammal takes. Short-beaked common dolphin are the most frequently taken species in the fishery, but since the observer program started in 1990, most of the cetacean species living off the coast have been entangled in gillnets including sperm whales, fin whales and several beaked whale species.
We have also begun to work with the Hawaii region, Pacific Islands Area Office, to incorporate the collection of skin samples from cetaceans entangled or accidentally killed in long line fishing gear. Several cetacean species have been observed entangled in the gear and little is known about these species from that area. We hope that the collection of skin for molecular genetic analyses will at least help us improve our understanding about the impacted species’ population structure.
For more information on fishery interactions:
EEZ Fishery Bycatch and Mortality
Fishery Effects on Dolphin Reproduction
stained cross section of tooth, below; looking at tooth on the image analyzer
Stock determination for Short-beaked common dolphin, Delphinus delphis, on U.S. West Coast.
Most recent estimates of mortality and description of life history data collected from the California drift gillnet fishery:
Carretta, J.V., and L. Enriquez. 2007. Marine mammal and sea turtle bycatch in the California/Oregon thresher shark and swordfish drift gillnet fishery in 2006. Administrative Report LJ-07-06, available from Southwest Fisheries Science Center, 8604 La Jolla Shores Drive, La Jolla, CA 92037. 9 pp.
Carretta, J.V., and L. Enriquez. 2006. Marine mammal bycatch and estimated mortality in California commercial fisheries during 2005. Administrative Report LJ-06-07, available from Southwest Fisheries Science Center, 8604 La Jolla Shores Drive, La Jolla, CA 92037. 16 pp.
Carretta, J.V., S.J. Chivers, and K. Danil. 2005. Preliminary estimates of marine mammal bycatch, mortality, and biological sampling of cetaceans in California gillnet fisheries for 2004. Administrative Report LJ-05-10, available from Southwest Fisheries Science Center, 8604 La Jolla Shores Drive, La Jolla, CA 92037. 17 pp.
Additional information about the California drift gillnet fishery:
Chivers, S. J., Robertson, K. M. and Henshaw, M. D. 1997. Composition of the incidental kill of cetaceans in two California gillnet fisheries: 1990-1995. Rep. Int. Whal. Comm. 47:909-15.
Hanan, D. A., Holts, D. B. and Coan, Jr., A. L. 1993. The California drift gillnet fishery for sharks and swordfish. Calif. Dept. of Fish and Game, Fishery Bulletin 175. 95 pp.
Jefferson, T. A., Myrick, Jr., A. C. and Chivers, S. J. 1994. Small cetacean dissection and sampling: A field guide. U. S. Department of Commerce, NOAA-Technical Memorandum-NMFS-SWFSC-198. 46pp.
Julian, F. and Beeson, M. 1998. Estimates of marine mammal, turtle, and seabird mortality for two California gillnet fisheries: 1990-1995. Fishery Bulletin 96:271-284.
Carretta, J.V., Price, T., Petersen, D., and Read, R. 2005. Estimates of marine mammal, sea turtle, and seabird mortality in the California drift gillnet fishery for swordfish and thresher shark, 1996-2002. Marine Fisheries Review 66(2):21-30.