overall means (12.8° and 13.3°C, respective- 

 ly). The greatest fluctuation in bottom and 

 surface salinities occurred between January 

 and May (Fig. 4), then they stabilized through- 

 out the remainder of the year. Because station 

 5 was located within the mouth of a fresh- 

 water tributary, the greatest range and 

 vertical variation in salinities were found 

 here. The overall mean for all stations was 

 31.5 & and the range 8.5-34.1%. 



Species Composition 



Thirty-seven species of larval and juvenile 

 fishes representing 17 families were collected 

 during the 12-month sampling period (Table 

 1). Of these, nine forms were not identifiable 

 beyond family and two only to superorder. 



Two were classified to genus and 24 to species. 

 The total catch of larvae and juveniles was 

 9,766, yielding an average of 0.13 larvae per 

 cubic meter of water sampled. 



The most speciose family was the Cottidae 

 with six species. Only two were identifiable; 

 the rest were present in too few numbers or 

 were not found in developmental series to 

 allow identification. In terms of abundance, 

 the bay goby, Lepidogobius lepidus, dominated 

 the catch and Pacific herring, Clupea harengus 

 pallasi, were almost as abundant; together 

 they comprised 82% of the total catch. The 

 bay goby, Pacific herring, Pacific staghorn 

 sculpin (Leptocottus armatus), longfin smelt 

 {Spirinchus thaleichthys), and the arrow goby 

 (Clevelandia ios) constituted 95% of all larvae 

 collected. 



Table 1. Species, month, size and numbers offish larvae and juveniles collected in Humboldt Bay, Calif. 



