Publication Date:
2021-06-30
Description:
In 1999 trap fishermen and environmental groups testified at a Fish and Game Commission (Commission) meeting that they were concerned about high levels of bycatch in the spot prawn trawl fishery. Environmental representatives requested that the Commission consider adopting regulations that would phase out the spot prawn trawl fishery by 2004 and convert spot prawn trawl permits to spot prawn trap permits.Also in 1999 the Department reported to the Commission the results of six observed spot prawn trawl tows in March 1999, including the ratio of weight of finfish bycatch toweight of spot prawns (7.4 to 1). Based primarily on the above factors, the Commission initially directed the Department to develop, as part of a package of regulatoryproposals for the spot prawn trap and trawl fisheries, a proposal to phase out the spot prawn trawl fishery and convert trawl permits to trap permits.Subsequently the Department recommended that, instead of phasing out the spot prawn trawl fishery, information on the relative amount and type of bycatch in the trawl and trap fisheries be determined through an on-board observer program.An observer fee structure was proposed and adopted, and an observer program was in effect for all vessels landing spot prawns from July 14, 2000 to March 31, 2001. Vessels were required to purchase and possess a spot prawn observer fee permit in order to take and land spot prawns. Funds from the program were used to support on board observers and to digitize and analyze the data. Some fishing trips wereobserved after the requirement for the observer fee had expired.A total of 86 spot prawn trawl tows (71 from northern California-based vessels and 15 from southern California- based vessels) was observed on nine vessels duringthe period September 26, 2000 to September 19, 2001. Observed vessels fished from the ports of Fort Bragg, San Francisco, Monterey, Morro Bay, and Ventura.For northern California trawl vessels, the top five finfish species observed in the bycatch, in decreasing frequency of occurrence, were Pacific hake (whiting), Doversole, sablefish, English sole, and splitnose rockfish, comprising 53.9% of all fishes by weight. Twenty-eight species of rockfishes were observed, comprising 28.1% byweight of all fishes. The weight ratio of total finfish bycatch to total spot prawn catchfrom all tows combined was 7.5 to 1. The ratio of total rockfish bycatch to total spot prawn catch was 2.1 to 1.For southern California trawl vessels, the top five finfish species observed in the bycatch, in decreasing frequency of occurrence, were Pacific sanddab, Pacific hake, slender sole, shortbelly rockfish, and Dover sole, comprising 83.1% of all fishes by weight. Fifteen species of rockfishes were observed, comprising 8.8% by weight of all fishes. The ratio of total finfish bycatch to total spot prawn catch from all tows combined was 17.7 to 1. The ratio of total rockfish bycatch to total spot prawn catch was 1.5 to 1.The ratio of total trawl bycatch, including invertebrates, to spot prawn catch was 8.8 to 1 in northern California and 20.6 to 1 in southern California.The National Marine Fisheries Service has determined the following rockfish species to be overfished and require rebuilding: bocaccio, canary, cowcod, darkblotched, widow, and yelloweye. Bocaccio, cowcod, darkblotched, and widowrockfishes were observed in multiple tows, and yelloweye and canary each were observed in a single tow. In general, the relative abundance of overfished rockfish species was low compared with other finfishes. However, expansions by weight of finfishes from observed tows to all spot prawn tows, based on the ratio of total to observed spot prawn landings, indicated that the estimated total bycatch of overfishedrockfishes was significant in terms of allowable catch levels (optimum yields) established by the Pacific Fishery Management Council (Council). Other overfishedspecies observed in the sampled catch including Pacific hake (whiting) and lingcod.Results from these trawl observations relative to bycatch levels were consistent with the few previous studies conducted. That is, the total observed bycatch in thetrawl fishery was more than four times that of spot prawns by weight.A total of 27 trap vessels paid the required observer fee, and 23 of these landed spot prawns during the period in which the observer fee was required. Passage wassecured on 16 of these 23 vessels for observations of bycatch. An additional vessel that had not paid the fee was sampled after the fee requirement period had expired. Atotal of 262 spot prawn trap strings (88 from northern California vessels and 174 from southern California vessels) was observed from 16 vessels during the study. Observedvessels fished out of the ports of Monterey, Morro Bay, Channel Islands Harbor, Ventura, Terminal Island, Newport Beach, Dana Point, Oceanside, and San Diego.For northern California trap vessels, the top five finfish species observed in the bycatch, in decreasing frequency of occurrence, were sablefish, rosethorn rockfish,greenblotched rockfish group, spotted cusk eel, and filetail catshark, comprising 77.7% of all fishes by weight. Seventeen species of rockfishes were observed, comprising25.5% by weight of all fishes. The ratio of total finfish bycatch to total spot prawn catch from all strings combined was 0.15 to 1. The ratio of total rockfish bycatch to total spot prawn catch was 0.04 to 1.For southern California trap vessels, the top five finfish species observed in the bycatch, in decreasing frequency of occurrence, were lingcod, greenblotched rockfishgroup, threadfin sculpin, sablefish, and swell shark, comprising 66.4% of all fishes by weight. Twenty-two species of rockfishes were observed, comprising 32.5% by weightof all fishes. The ratio of total finfish bycatch to total spot prawn catch from all strings combined was 0.22 to 1. The ratio of total rockfish bycatch to total spot prawn catch was 0.07 to 1.The ratio of total trap bycatch, including invertebrates, to spot prawn catch was 1.0 to 1 in northern California and 2.0 to 1 in southern California. Most invertebrates and many fish species other than rockfishes could be returned to the water alive.Overfished rockfish species were observed infrequently, and expansions of observed bycatch data to all trap strings yielded relatively low total estimated bycatch weights for these species.In northern California, the relative amount of bycatch for all finfishes and rockfishes was 50 and 52 times greater, respectively, in the trawl fishery compared withthe trap fishery. In southern California, the relative amount of bycatch for all fishes and rockfishes was 80 and 21 times greater, respectively, in the trawl fishery compared with the trap fishery. (Document has 88 pages)
Keywords:
Management
;
Fisheries
;
Biology
;
bycatch
;
trawl fishery
;
trap fishery
;
spot prawns
;
California
Repository Name:
AquaDocs
Type:
monograph
Format:
application/pdf
Format:
application/pdf
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