FISHERY BULLETIN: VOL. 83, NO. 4 



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c 

 a 



cn 



Q 



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o 



_co 

 o" 



_CD 

 O 



o 

 O 



Oceanic-Davidson 



Females 



30-49 mm 

 n = 2l 



PRfls 



30-49mm 

 n=20 



30-49mm 

 n=27 



Id D^» r« 



50-59mm 

 n=l3 



Current Periods 



Males 



40-49mm 

 n=6 



50-69mm 

 n=45 



50-69mm 

 n=5 



50-69mm 

 n=6 



o 30-49mm 

 ^ n=24 



50-69mm 

 n=38 



^ 30 -49 mm 

 S n=40 



50-69mm 

 n=20 



70-79mm 

 n=4 



Figure 4.— Sex-specific ontogenetic and among year variation in Oligocottus snyderi feeding habits during the 

 three ODC (Oceanic-Davidson Current) periods encompassed by this study. Prey are represented as percent 

 total prey weight; only prey composing >1% total prey weight are shown. Asterisks indicate prey occurring 

 in only one individual. Abbreviations are as in Figure 3, with the addition of E (eggs); An (sea anemones); 

 and Bi (bivalves). 



after 1 yr (Jones 1962; Tksto 1975). Oligocottiis 

 snyderi and 0. maculosus apparently are best 

 characterized by the short hfespan, early matura- 

 tion, life history pattern. This conclusion is based 

 on growth rate data coupled with the scarcity of in- 

 dividuals older than 1.5 yr, and data showing early 

 maturation and high reproductive effort for 0. 

 snyderi (deVlaming et al. 1982). 



The majority of age 0+ 0. snyderi at Dillon Beach 

 attained sufficient size to spawn during their first 

 year; it is less certain what proportion of these in- 

 dividuals survive to spawn in their second year. 

 Grossman and deVlaming (1984) indicated that, at 

 Dillon Beach, females mature at about 40 mm SL 

 and contain vitellogenic oocytes from October 

 through May. These females also probably spawn 

 more than once, primarily during winter and spring 

 (Grossman and deVlaming 1984). Length-frequency 

 distributions from March and May 1979 and March 

 and April 1980 show that a single age class 

 dominated the population. Hence, assuming that 

 recruitment primarily was derived from this popula- 



tion, age 1+ individuals (recruited the previous 

 spring and summer) must have been responsible for 

 nearly all spring spawning. The paucity of large in- 

 dividuals (i.e., >60 mm SL) in winter or spring 

 samples indicates that if individuals spawned in their 

 second year, this reproduction must have occurred 

 prior to January. Substantial numbers of age 1 -i- in- 

 dividuals were captured from October to December 

 1979 and in November 1980. Although the earliest 

 recruitment observed at Dillon Beach occurred in 

 March 1980, Moring (1981) captured newly recruited 

 individuals as early as January. This suggests that 

 fall spawning may occur in more northerly popula- 

 tions of 0. snyderi. 



Reproduction apparently is timed to insure that 

 larvae metamorphose during upwelling. Grossman 

 (1982) found a significant correlation between up- 

 welling activity and the number of resident species 

 with young-of-the-year present at Dillon Beach. 

 Grossman and deVlaming (1984) also observed that 

 0. snyderi recruitment was strongly correlated with 

 productivity; the authors pointed out that the early 



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