Rockfishes of the family Scorpaenidae form one of the im- 

 portant and largest fish families off California. Rockfishes are 

 also considered a much underutilized fishery resource of Cali- 

 fornia in terms of abundance (Frey 1971). This family is repre- 

 sented by three genera in California, with at least 55 species of 

 Sebastes spp., a single species of Scorpaena, and 2 species of 

 Sebastolobus (Phillips 1964; Frey 1971). 



No estimate of the rockfish biomass has been made. It is 

 known in general terms as a large resource, and because rock- 

 fish are a highly desirable food resource they are subjected to 

 both commercial and sportfishing pressure. The larvae of 

 Sebastes spp. have consistently ranked third or fourth in abun- 

 dance in the CalCOFI survey area (Ahlstrom 1968). The com- 

 mercial catch reached a maximum of 8 million kg in 1958 but 

 since has dropped to about 4 million kg (Fig. 14). CalCOFI 

 surveys show that the larvae of various species of rockfish oc- 

 cur in great abundance and are widely distributed along the 

 coast as far as 500 km offshore. During their pelagic existence, 

 rockfishes sometimes form a large and important part of the 

 diet of chinook salmon, Oncorhynchus tshawytscha; albacore; 

 and petrale sole, Eopsetta jordani (Phillips 1957). 



Perhaps because of the numerous head spines of rockfishes, 

 fur seals have always beheaded the adult rockfishes before 

 swallowing them as only bodies have been found in their stom- 

 achs. This was generally the situation off Washington when 

 rockfish was the principal prey species during February, 

 March, and April (Table 6). As previously mentioned, most 

 rockfish taken by fur seals off California were juveniles. Lar- 

 val and juvenile rockfish were available from the surface to 

 140 m depth during CalCOFI survey cruises (Ahlstrom 1965). 















* 

 + 



b Eureka 



* 



+ 



O 

 V 

 < 



O 



\ 



V 

 ^s/S San Francisco 

 + + f Monierey 



# + * X 



+ 1 



Pt. Conception 



Jack mackerel. — Jack mackerel is among the leading forage 

 species of fur seals collected during April and June off Califor- 

 nia. The principal locations where this fish occurred, as indi- 

 cated in stomachs of fur seals, are shown in Figure 23. The 

 jack mackerel was second only to the anchovy in frequency of 

 occurrence in midwater trawl catches conducted by CalCOFI 

 scientists, with the highest catch rates and largest catches made 

 in the southern and northern California regions (Mais 1974). 

 Jack mackerel larvae are abundant in offshore regions from 

 March through July (Kramer and Smith 1970). 



Although the jack mackerel is widely distributed through 

 the eastern North Pacific Ocean from Baja California, Mex- 

 ico, to the Aleutian Islands (Fig. 24), it occurred in only one 

 stomach of a fur seal north of California during 1958-74, 

 probably because jack mackerel prefer warmer water and 

 migrate into the Gulf of Alaska only in summer. Very few seals 

 have been collected during summer in areas outside the Bering 

 Sea. 



Jack mackerel exhibit both coastal (north-south) and inshore- 

 offshore movements. The larger and older fish are found off- 

 shore in deeper water, whereas the younger fish are generally 

 found over rocky banks and shallow coastal areas (MacCall et 

 al. 1980). Juvenile jack mackerel stay inshore (0-90 km) for the 

 first 3 to 6 yr of their lives, gradually moving farther offshore 

 with increasing age and size. Young fish commonly school 

 beneath floating kelp in the open ocean (Mais 1974). Fur seals, 

 which are often found in association with floating kelp, may 

 be attracted by these juvenile jack mackerel. 



The entire jack mackerel resource of the eastern Pacific 

 Ocean was estimated between 2.1 and 4.8 million tons and the 

 California and Baja California resource at 1.4 to 2.4 million 



Figure 23. — Locations off California where 114 northern fur seals were collected 

 whose stomachs contained jack mackerel, 1958-66. 



i r 



l 1 i r 



30° - 



1 and 2 Gillnet catches 

 3 and 5 Eggs and larvae 



4 Night light stations 



20°" 1 1 1 1 1 I I 'I'l 



160° 150° 140° 130° 120° 1 10 



Figure 24. — Distribution of the jack mackerel resource (modified from MacCall et 

 al. 1980). 



19 



