806 



Fishery Bulletin 101(4) 



500 



400 



^ 300 



200 



100 



Females (OR, McClure, 1982) 



Males (OR, McClure, 1982) 



■Miller and Geibel (1973) 

 -MacGregor (1983) 



9 



Age (yr) 



12 



15 



Figure 7 



Growth models from five published studies of blue rockfish (Sebastes mystinus). 



from 0.04/year for female silvergrey rockfish to 0.62/year 

 for the shorter-lived dwarf Puget Sound rockfish, with the 

 average range of ^ values occurring from 0.1 to 0.3/years 

 (Love et al,, 1990; Beckman et al., 1998). This considerable 

 longevity and relatively slow growth rate have significant 

 effects on the ability of many rockfish stocks to withstand 

 exploitation. 



The age and growth relationships described in this 

 study indicate that both recruitment of blue rockfish to 

 the fishery and their maturity occur at younger ages than 

 previously reported. Blue rockfish enter the fishery at a 

 size of approximately 200 mm (Miller et al., 1967; Miller 

 and Geibel, 1973). This length equates to ages of 2-4 years 

 as determined in our study compared to 3-5 years as es- 

 timated by Miller et al. (1967). The new estimates for age 

 at which 50% of individuals are mature (using fish lengths 

 from Miller and Geibel, 1973) are even more striking: our 

 estimated age at 50% maturity is 5-6 years for males and 

 5 years for females, whereas estimates from Miller and 

 Geibel ( 1973) and Echeverria ( 1986) were 7 years for males 

 and 7-8 years for females. Similarly, the youngest mature 

 males and females in these early studies were 4-5 years, 

 whereas we estimated the age to be 3 years. 



The changes observed in our study in age-at-length, 

 maximum age, recruitment age, and age at 50% matu- 

 rity have important implications for stock assessments. 

 Accurate information on age composition, weight-at-age, 

 age specific availability to the fishery, and maturity-at-age 

 is crucial to the proper functioning of the stock synthe- 

 sis model (Methot, 1990), which is used for Pacific coast 

 groundfish. If incorrect age data are used, it could lead to 



erroneous estimates of population size, and subsequently 

 to either overfishing or an unnecessary reduction in allow- 

 able catch. 



Acknowledgments 



We would like to thank all the port samplers who collected 

 the CPFV catch data. We also thank the crew and scientific 

 personnel aboard the RV David Starr Jordan for collecting 

 samples. We thank James Chess, Edmund Hobson, Dan 

 Howard, and Kelly Silberberg for braving the cold waters 

 of the Pacific Ocean to collect the nearshore specimens. 

 We also thank Churchill Grimes and Mary Yoklavich for 

 their many constructive comments and the reviewers of 

 this manuscript. 



Literature cited 



Beamish, R. J., and D. A. Fournier. 



1981. A method of comparing the precision of a set of age 

 determinations. Can. J. Fish. Aquat. Sci. 38:982-983. 

 Beamish, R. J., and G. A. MacFarlane. 



1987, Current trends in age determination methodology. In 

 Age and growth of fish (R. C. Summerfelt and G. E. Hall, 

 eds), p. 15-42. Iowa State Univ, Press, Ames, lA, 

 Beckmann, A. T., D, R. Gunderson, B. S. Miller, R. M. Buckley, 

 and B. Goetz. 



1998. Reproductive biology, growth, and natural mortality 

 of Puget Sound rockfish, Sebastes emphaeus (Starks, 1911). 

 Fish, Bull. 96:352-356. 



