HEADY. E. O.. AND. J. L. DILLON. 



1972. Agricultural production functions. Iowa State Univ. 

 Press. Ames, 667 p. 



papoulis, a. 



1965. Probability, random variables and stochastic pro- 

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 TOMOVIC. R.. AND M. VUKOBRATOVIC. 



1972. General sensitivity theory. .■Xm. Elsevier, N.Y., 258 p. 

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1972. Introductory systems engineering. McGraw Hi 

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Southeast Fisheries Center Miami Laboratory 

 National Marine Fisheries Service, NOAA 

 75 Virginia Beach Drive. Miami, Fla. 

 Present address: Department ofEngineeri 

 Stanford University, Stanford, CA 94305 



from preserved fish. Ovaries were histologically 

 classified into four stages (Table 1). 



Table l. — Monthly di.stribution (percent) of ovarian stages in 

 the yearly spawning cycle of Peprilus simillimus, September 

 1978-August 1979. 



Regressed or Pre- Pre- 



Month N regressing vitellogenic Vitellogenic spawning 



Results 



SEASONAL SPAWNING CYCLE OF 



THE PACIFIC BUTTERFISH, 



PEPRILUS SIMILLIMUS (STROM ATEI DAE) 



There is little information on the reproductive bi- 

 ology of the Pacific butterfish, Peprilus simillimus , 

 which ranges from Magdalena Bay, Baja Califor- 

 nia, to the Fraser River, British Columbia, and 

 occurs at depths of 9-91 m (Miller and Lea 1972). It 

 is commercially fished with purse seine, lampera, 

 and bait net (Fitch and Lavenberg 1971). In 1976, 

 34.18 t were taken in California (Oliphant 1979). 

 Fitch and Lavenberg (1971) reported spawning oc- 

 curs in spring and extends perhaps into July. Horn 

 (1970) studied the systematics and biology of the 

 genus Peprilus. My purpose is to describe his- 

 tologically the seasonal spawning cycle of the 

 Pacific butterfish. 



Methods 



Fish were collected with the use of a lampera net 

 between depths of 2 and 20 m from the vicinity of 

 Oceanside, southern California (lat. 33°10' N, 

 long. 117°25' W), during the period September 

 1978 through August 1979. Only female specimens 

 were examined. Fish were fixed and preserved in 

 10% Formalin. 1 Ovarian histological sections from 

 232 specimens were cut at 8 /zm and stained with 

 iron hematoxylin. Seasonal gonosomatic indices 

 (ovary weight/fish weight x 100) were calculated 



'Reference to trade names does not imply endorsement by the 

 National Marine Fisheries Service. NOAA. 



FISHERY BULLETIN: VOL. 78. NO. 4, 1981. 



Ovaries were regressed ( Stage 1 ) during autumn 

 (September- November) and consisted of primary 

 oocytes <100 /u,m in diameter (Table 1). Gonosomat- 

 ic indices (Figure 1) were reduced at this time. 

 The first signs of ovarian activity for the new 

 spawning cycle were noted during December. This 

 was determined by an abundance of previtel- 

 logenic (vacuolated) (Stage 2) oocytes (130-200 

 fjLTn) which typically appear before yolk deposition 

 begins (Table 1). Enlarging (Stage 3) vitellogenic 

 oocytes (yolk deposition in progress) were first 

 noted in January. The first ripe (prespawning or 

 gravid) (Stage 4) females with ovaries containing 



12.0 



o 

 o 



>- 



Q 

 O 



m 



>- 

 cr 

 < 

 > 

 o 



10.0 



8.0 



SEP OCT NOV DEC JAN FEB MAR APR MAY JUN JUL AUG 

 1978 1979 



Figure l. — Seasonal gonosomatic indices for Peprilus similli- 

 mus. Vertical line = range: horizontal line = mean: rectangle = 

 95*7^ confidence interval. Sample size above each month. 



977 



