co 



<1> 



E 



o 



> 



<0 



C 



o 



2.5 



2.0 



1.5 



-^ Sep. 1980 



*---* Sep. 1983 



• • Dec. 1980 



• • Dec. 1983 



6.0 6.1 



In (total length-mm) 



6.2 



1980 were not expected. December is later than the 

 normal period of sexual activity for males, but the 

 unexpected gonad volume results may be caused by 

 delayed mating. The gonad stage data indicated that 

 male sexual activity was later in 1983 than in 1980. 

 While fish condition and reproduction were dif- 

 ferent in 1983 than in the preceding non-El Nino 

 years, the documentation of such differences for 

 marine fish is uncommon. The season of parturition 

 of yellowtail rockfish is more variable than we 

 realized when the study was designed and the data 

 on fish condition and gonad volume should have been 

 collected over a wider period of time. The results 

 of our study indicate that the assumption of constant 

 adult fish condition and reproductive effort that is 

 usually made in models of the population dynamics 

 of fish is questionable. 



5.0 



■= 4.0 



<D 



E 



o 



> 



■D 



CO 



c 

 o 



3.0 



2.0 



1.0 



* * Sep. 1980 



*- — ■* Sep. 1983 



• «Dec. 1980 



• ^Dec. 1983 



5.9 6.0 6.1 6.2 6.3 

 In (total length-mm) 



Figure 2.— Relationships between In (gonad volume) and In (total 

 length) for yellowtail rockfish in 1980 and 1983. (Top) males; 

 (bottom) females. 



Table 3.— Percent of yellowtail rockfish females with eyed-larvae 

 observed in samples collected in central and northern California, 

 1981-1984. 



The lower ovary volumes in 1983 than 1980 could 

 have been related to either delayed parturition 

 and/or lower reproductive effort. Wootton (1979) 

 described relationships between feeding conditions 

 and fish fecundity. The significantly higher gonad 

 volumes for males in December 1983 compared with 



Literature Cited 



BOEHLERT, G. W., AND M. M. YOKLAVICH. 



1984. Reproduction, embryonic energetics, and the maternal- 

 fetal relationship in the viviparous genus Sebastes (Pisces: 

 Scorpaenidae). Biol. Bull. (Woods Hole) 167:354-370. 



Guillemot, P. J. 



1982. Seasonal cycles of fat content and gonad volume in 

 species of northern California rockfish (Scorpaenidae; 

 Sebastes). M.A. Thesis, San Francisco State Univ., San 

 Francisco, CA, 167 p. 



Guillemot, P. J., R. J. Larson, and W. H. Lenarz. 



1985. Seasonal cycles of fat and gonad volume in five species 

 of northern California rockfish (Scorpaenidae; 

 Sebastes). Fish. Bull., U.S. 83:299-311. 



Kleinbaum, D. G., and L. L. Kupper. 



1978. Applied regression analysis and other multivariable 

 methods. Duxbury Press, North Scituate, MA, 556 p. 



Lorz, H. V., W. G. Pearcy, and M. Fraidenburg. 



1983. Notes on the feeding habits of the yellowtail rockfish, 

 Sebastes flavidus, off Washington and in Queen Charlotte 

 Sound. Calif. Fish Game 69:33-38. 



Pereyra, W. T., W. G. Pearcy, and F. E. Carvey, Jr. 



1969. Sebastodes flavidus, a shelf rockfish feeding on meso- 

 pelagic fauna, with consideration of the ecological implica- 

 tions. J. Fish. Res. Board Can. 26:2211-2215. 

 Phillips, J. B. 



1964. Life history studies on ten species of rockfish (genus 

 Sebastodes). Calif. Dep. Fish Game, Fish Bull. 126, 70 p. 

 Rasmusson, E. M. 



1984. El Nino: the ocean/atmospheric connection. Oceanus 

 27 (2):5-12. 



Wootton, R. J. 



1979. Energy costs of egg production and environmental 

 determinants of fecundity in teleost fishes. Symp. Zool. 

 Soc. Lond. No. 44, p. 133-159. 



William H. Lenarz 

 Tina Wyllie Echeverria 



Southwest Fisheries Center Tiburon Laboratory 

 National Marine Fisheries Service, NOAA 

 3150 Paradise Drive 

 Tiburon, CA 94920 



745 



