Reference | Nakamura, R. 1991. A survey of the Pacific hagfish resource off the Central California Coast. Final report to the Secretary of Environmental Affairs, Office of Environmental Protection, Marine Fisheries Impacts Programs (Contract agreement A-800-184), Biological Sciences Department, CA Polytechnic State U., San Luis Obispo, CA. |
Abstract | A field survey and laboratory study of Pacific hagfish was conducted to characterize the population(s) off the Central California Coast. The results of the study indicate hagfish are most abundant between the 35-50 and 150 fathom isobaths. No major seasonal changes in overall population size structure were observed. Hagfish become reproductively mature at a size smaller (12.8 inches) than that targeted optimum size (13.8 inches) of the buyer and processor. Thus fish landings probably consist mainly of fish which have spawned at least once. However, it should be noted that many younger fish are also caught with many being discarded and probably lost from the population through handling associated mortality. Although numerous immature eggs can be found in a mature female. Pacific hagfish do not produce many mature eggs in spawning cycle, averaging only about 23-24 eggs per cycle. While tagging and other studies suggest very high population densities (300,000 to 442,697 sq. km.), it should be noted that a large spawning population is absolutely essential to balance off the low egg production of individual fish per spawning cycle. Limited growth data and preliminary extrapolation suggest yearling hagfish to be about 4.8” while the targeted 14 inch hagfish may range between 5+ to 9+ years in age. Preliminary 1990 catch statistics show landings in Morro Bay and Port San Luis of over 608,000 lbs., which is estimated to be composed of 3.8 million fish between 11.8 and 21.8 inches respectively. Long term maintenance of the stock requires special consideration of low egg production rates/female/cycle and the necessity for a large spawning population. It should also be noted that virtually nothing is known of the development time and location of eggs and newly hatched hagfishes. |
Tag | Coded Wire Tag (CWT) |
Objective | Population estimates |