DARK: AGE AND GROWTH OF PACIFIC HAKE 



migration to the south which terminates in the 

 spawning area off southern California and 

 Mexico. The eggs and larvae drift onto the con- 

 tinental shelf and the young inhabit the waters of 

 California and Oregon as l-to-3 yr-olds. Some 3- 

 yr-olds and most 4-yr-olds become sexually mature 

 (Best 1963) and are recruited to the adult popula- 

 tion. 



Pacific hake were landed in small quantities in 

 California ports as early as 1879. California land- 

 ings from 1916 to 1951 varied from about 0.2 to 90 

 metric tons. An animal food fishery developed in 

 1952 creating an increased demand for low value 

 species and hake landings increased to about 590 

 metric tons in 1956. From 1956 to 1968, landings 

 averaged about 200 metric tons annually. 



Prior to 1965 Washington and Oregon fishermen 

 did not purposefully fish for hake and, in fact, 

 considered them a nuisance species. In 1965 a small 

 fishery was initiated under the guidance of the 

 U.S. Bureau of Commercial Fisheries (BCF)- to 

 examine the feasibility of efficiently harvesting 

 Pacific hake off Washington and Oregon. Four 

 vessels began fishing commercially in 1966 because 

 favorable results were obtained from the 

 feasibility study and a new fish reduction plant 

 had begun operations at Aberdeen, Wash. During 

 the same year a large Soviet trawl fleet appeared 

 off the Washington-Oregon coast fishing for 

 rockfish, Sebastes spp., and Pacific hake. Competi- 

 tion from the Soviet fleet was so severe that it 

 seriously threatened the existence of the U.S. 

 fishery. Negotiations between the United States 

 and the Soviet Union in February 1967 resulted in 

 an agreement which restricted the size of the 

 Soviet fishing area off the southern Washington 

 coast. The U.S. fleet was more successful in 1967 

 because of a reduction of Soviet competition and 

 increased efficiency of U.S. vessels. This greater 

 efficiency stemmed from the increased experience 

 of fishermen, improved fishing gear, and greater 

 scouting capability. The total U.S. catch in 1967 

 was 8,381 metric tons (catch-per-unit-effort 

 [CPUE] = 4.5 metric tons/h), as compared to a 

 total catch of 1,694 metric tons (CPUE = 3.0 me- 

 tric tons/h) in 1966 (Nelson 1970). Soviet catches in 

 1966 and 1967 were about 136,050 and 170,590 me- 

 tric tons, respectively. Since 1967 the Soviets have 

 continued to fish for Pacific hake and annual 

 catches have averaged about 140,000 metric tons. 

 The U.S. fishery was discontinued in 1968 when the 



Presently, the National Marine Fisheries Service. 



reduction industry, facing a depressed fish meal 

 market, was unable to give vessel owners prices 

 that were competitive with those offered by the 

 shrimp and groundfish processors (Pereyra and 

 Richards 1970). 



An agreement pertaining to the joint exploita- 

 tion of groundfish in the northeast Pacific Ocean 

 was negotiated between the United States and the 

 Soviet Union in 1967 and renegotiated in 1969 and 

 1971. Scientific meetings have been held annually 

 to discuss problems of mutual concern such as as- 

 sessing the size of the Pacific hake population, de- 

 termining the effects of the fishery, and estimat- 

 ing rates of growth, mortality, and maximum 

 sustainable yield. Recommendations resulting 

 from the scientific meetings provide a basis for 

 modification of the bilateral fishery agree- 

 ment—which can be done every 2 yr. 



Initial growth estimates were based on 

 preliminary data but served to provide essential 

 real time estimates of maximum sustainable yield. 

 Subsequently, additional data have been collected 

 allowing for refinement of early growth estimates. 

 The objectives of the present study were to 

 provide new estimates of the growth rate of 

 Pacific hake and to examine some of the potential 

 sources of variation. An analysis was made of the 

 reliability of the age determination method used 

 since age information is basic to growth studies. 

 The variability in the age structure of the Pacific 

 hake population was also examined since age 

 composition is frequently used to evaluate relative 

 year class strengths, mortality rates, and the ef- 

 fects of fishing. 



SAMPLING 

 Collection Methods 



Biological data were collected from two sources: 

 "commercial" samples from the commercial 

 fishery and "research" samples taken aboard 

 research vessels. 



Commercial samples were taken mainly in 

 1966-67 when a U.S. hake fishery was conducted 

 off the Washington coast during May-September. 

 A sampling station was established at the reduc- 

 tion plant in Aberdeen, Wash., where essentially 

 all hake taken off Washington and Oregon were 

 landed. An attempt was made to man the station 

 every other week and to sample the catches as they 

 were unloaded at the plant. Irregular landing 

 schedules, especially in 1966, resulted in sporadic 



337 



