DISTRIBUTIONAL PATTERNS OF FISHES CAPTURED ABOARD 



COMMERCIAL PASSENGER FISHING VESSELS 



ALONG THE NORTHERN CHANNEL ISLANDS, CALIFORNIA 



Milton S. Love.i William Westphal,' and Robson A. Collins^ 



ABSTRACT 



We surveyed fishes taken aboard commercial passenger fishing vessels alon^ the four northern Channel 

 Islands (San Miguel, Santa Rosa, Santa Cru?, and Anacapa) within the Southern California Bight. P'ourteen 

 species declined in abundance along the Northern Channel Island chain. Colder water forms decreased to 

 the east, while temperate species declined to the west. In the shallowest depth interval (0-36 m). the mean 

 lengths of four rockfish species increased toward the west. In general, the size of these four species also in- 

 creased with depth. We believe these phenomena are linked to the differences in water temperature be- 

 tween the islands- with cold, California Current water dominant in the west, and warmer Southern Califor- 

 nia Bight water entrained in the east. 



The mainland coast of California is distinguished by 

 two faunal provinces: A warm-temperate Californian 

 Province lies south of Point Conception and a cold- 

 temperate Oregonian Province exists to the north 

 (Seapy and Littler 1980). In shallow waters, the fish 

 fauna of the Californian Province is a mixture of 

 eurythermic temperate and subtropical species, 

 while the Oregonian Province is predominantly a 

 colder temperate region, with few subtropical 

 species present. 



Recent studies examining the distributional pat- 

 terns of marine intertidal invertebrates (Littler 

 1980; Seapy and Littler 1980), algae (Murray et al. 

 1980), and seabirds (Hunt et al. 1980) around south- 

 em California islands imply there is a replication of 

 these two mainland faunal provinces along the 88 

 km, east-west lying, northern Channel Islands (San 

 Miguel, Santa Rosa, Santa Cruz, Anacapa) (Fig. 1). 

 Oregonian Province species dominate the western 

 end of the chain, while the fauna of the eastern end is 

 more Californian. 



There is little published on the biogeography of 

 fishes around the northern Channel Islands. Ebeling 

 et al. (1980a, b) examined the fish populations of 

 Santa Cruz Island kelp beds, and Hubbs (1967, 1974) 

 stated that the fish communities of San Miguel were 

 closely related to those of central California, while 

 about Santa Cruz fish were typical of southern Cali- 



iVANTONA Research Group, Moore Laboratory of Zoology, 

 Occidental College, Los Angeles, CA 9004 L 



^Marine Resources Branch, California Department of Fish and 

 Game, 1301 W. 12th, Long Beach, CA 90813. 



fornia. No other work has been published on this 

 topic. 



In this paper, we describe one aspect of the north- 

 ern Channel Islands' fish fauna, utilizing data 

 gathered by the California Department of Fish and 

 Game in their Commercial Passenger Fishing Vessel 

 creel census. This census (fully described in Methods) 

 counted, measured, and noted the location and depth 

 of capture of fishes taken by hook and line on sport- 

 fishing passenger vessels in southern California. 



Data from this study could not give an unbiased 

 estimate of species composition. Most angling in- 

 volved fishing with live bait (primarily northern an- 

 chovies, Engraulis mordax) or with lures simulating 

 fishes, and angling techniques were similar along the 

 island chain. Thus, the sample was biased toward 

 relatively large-mouthed, piscivorous species. 

 However, the purpose of this study was to ascertain 

 distributional patterns of whatever species were 

 taken by these methods, rather than attempting to 

 describe entire fish communities. 



METHODS 



Fishes taken aboard commercial passenger fishing 

 vessels (CPFV) were sampled by the senior author 

 and by California Department of Fish and Game per- 

 sonnel from April 1975 to December 1978. The sam- 

 pling units (trips) were chosen randomly, and the 

 population sampled consisted of all regularly sched- 

 uled trips by CPFV's operating south of Point Con- 

 ception to the Mexican border. 



The sampler assigned to each boat boarded the 



Manuscript accepted August 1984. 



FISHERY BULLETIN: VOL. 83, NO. 3, 1985. 



243 



