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Fishery Bulletin 89|I), 1991 



value corresponding to the optimum length-at-entry 

 (Beverton and Holt 1966). The results of the model are 

 particularly sensitive to levels of M/K, asymptotic 

 weight, and market price. Interestingly, the results de- 

 pend only on the ratio of M to K, and the slow growth 

 of rockfish does not have a bearing on the equilibrium 

 benefit of the released juveniles. Three commercially 

 important species— Pacific ocean perch, yellowtail rock- 

 fish Sebastes Jlavidus, and canary rockfish S. tfinni- 

 ger— have M/K values around 0.5 and, from a popula- 

 tion dynamics standpoint, offer the most potential for 

 hatchery releases (Table 1). 



Based on the Deriso-Schnute model, the level of 

 Fmsy f° r Pacific ocean perch in Queen Charlotte 

 Sound is estimated at 0.06 per year. This value is con- 

 sistent with the finding of Archibald et al. (1983) and 

 considerably less than the F levels of 0.2-0.5 per year 

 during the depletion of the stock. Given the slow 

 growth and long lag between spawning and recruit- 

 ment to the fishery, stock recovery for rockfish is a 

 long-term process. Fishery managers must decide 

 whether the goal of the recovery program is to return 

 the stock to B M sy as quickly as possible or to follow 

 a more gradual return while allowing fishing. Under 

 both approaches, stocking reduces the time to reach 

 B MSY and increases the yield to the fishery. Both bene- 

 fits must be considered in evaluating the merits of a 

 hatchery-release program for stock recovery. As with 

 the yield-per-recruit analysis, Pacific ocean perch, 

 yellowtail rockfish, and canary rockfish are the three 

 commercial species, based on their low M/K ratios, that 

 offer the most potential for stock recovery with hatch- 

 ery releases (Table 1). 



Based on population-dynamics considerations, the 

 use of hatchery releases for fishery enhancement ap- 

 pears to have merit for certain species of rockfishes. 

 However, population dynamics represents only one 

 part of the post-release ecology, and a fuller under- 

 standing of this ecology is necessary to predict the 

 success of hatchery releases. For example, hatchery- 

 reared Kuruma prawns Penaeus japonicus were re- 

 leased in a number of similar locations around Japan 

 (Isibasi 1984). Increases in catches were documented 

 in some instances, but no changes were evident in many 

 others; researchers generally were unable to explain 

 this variation (Isibasi 1984). While this analysis as- 

 sumes that large-scale hatchery releases are possible, 

 no such releases have been done, and nothing is known 

 of the economics of a rockfish hatchery. Further, 

 hatchery-released juveniles have been assumed to have 

 the same behavior and natural mortality as wild stock. 

 This may be an overly optimistic assumption because 

 pilot hatchery releases for other species often have 

 higher and more variable natural mortality than is 

 thought to occur in wild stock (Kyokai 1983). 



Citations 



Archibald, C.P., D. Fournier, and B.M. Leaman 



1983 Reconstruction of stock history and development of reha- 

 bilitation strategies for Pacific ocean perch in Queen Charlotte 

 Sound, Canada. N. Am. J. Fish. Manage. 3:283-294. 



Beverton, R.J.H., and S.J. Holt 



1966 Manual of methods for fish stock assessment. Part II - 



Tables of yield functions. FAO Fish. Tech. Pap. 38 (Rev. 1 ), 



67 p. 

 Botsford, L.W., and R.C. Hobbs 



1984 Optimal fishery policy with artificial enhancement 

 through stocking: California's white sturgeon as an exam- 

 ple. Ecol. Modell. 23:293-312. 



Deriso, R.B. 



1980 Harvesting strategies and parameter estimation for an 

 age-structured model. Can. J. Fish. Aquat. Sci. 37:268-282. 

 Isibasi, K. 



1984 A statistical assessment on the effect of liberation of lar- 

 vae in the sea farming— I. On the effect of liberation in the 

 case of Kuruma prawn {Penaeus japonicus). Bull. Tokai Reg. 

 Fish. Res. Lab. 113:141-155. 



Ito, D.H., D.K. Kimura, and M.E. Wilkins 



1987 Status and future prospects for the Pacific ocean perch 

 resource in waters off Washington and Oregon as assessed in 

 1986. NOAA Tech. Memo. NMFS-F/NWC-113, Northwest & 

 Alaska Fish. Sci. Cent., 7600 Sand Point Way NE, Seattle 

 98115, 50 p. 



Kusakari, M. 



In press Mariculture of kurosoi, Sebastes schlegeli. Environ. 

 Biol. Fish. 

 Kyokai, S. (editor) 



1983 Tsukuru gyogyo. Norin Tokei Kyokai (Agric. For. Stat. 

 Assoc), 753 p. [in Jpn., Engl, transl. of Table of Contents only 

 by T. Otsu, 1987; full translation avail, from JJP]. 



National Marine Fisheries Service 



1989 Fisheries of the United States, 1988. U.S. Natl. Mar. 

 Fish. Serv. Curr. Fish. Stat. 8800, 116 p. 

 Pacific Fishery Management Council 



1989 Pacific coast groundfish fishery management plan, draft 

 amendment 4. Pac. Fish. Manage. Counc, Portland, OR, 52 p. 

 Sakai, K., H. Nagashima, and K. Kiso 



1985 Growth and movement of artificially reared young rock- 

 fish, Sebastes schlegeli, after release in Matsushima Bay. Bull. 

 Tohoku Reg. Fish. Res. Lab. 47:21-32 [in Jpn.. Engl, abstr; 

 Engl, transl. 125 by W.G. Van Campen, 1988, 19 p., avail. 

 Honolulu Lab., Southwest Fish. Cent.. Natl. Mar. Fish. Serv., 

 NOAA, Honolulu, HI 96822-2396]. 



Schnute, J. 



1985 A general theory for analysis of catch and effort data. 

 Can. J. Fish. Aquat. Sci. 42:414-429. 

 Ulltang, O. 



1984 The management of cod stocks with special reference to 

 growth and recruitment overfishing and the question whether 

 artificial propagation can help to solve management problems. 

 In Dahl, E., D.S. Danielssen, E. Moksness, and P. Solemdal 

 (eds.), The propagation of cod Gadus rnorhua L., p. 795-817. 

 Fl(Jdevigen rapp., 1. 



Yatsuyanagi, K. 



1982 Productive effect in stocking of prawn seedling in waters 

 adjacent to Yamaguchi Pref. and Suho-Nada. Bull. Yamagu- 

 chi Prefect. Naikai Fish. Exp. Stn. 10:1-52. 



Zheng, J., and C.J. Walters 



1988 Population dynamics and stock assessment of Wanshan 

 Spring Decapterus maruadsi (T.&S.) in South China 

 Sea. Fish. Res. (Amst.) 6:217-231. 



