LOVE ET AL.: DISTRIBUTIONAL PAITERNS OF FISHES 



the western islands. Similarly, fishes more charac- 

 teristic of the Oregonian Province (Ophiodon 

 elongatus, Sebastes caurimcs, S. nebulosus) were less 

 abundant or absent off Santa Cruz and Anacapa. 

 Evidence from Miller and Lea (1972) bolsters this 

 impression. Nineteen species have geographic range 

 limits along the island chain; of these, 9 (Anoplar- 

 chus purpurescens, Artedius harringtoni, 

 Chirolophis nugator, Hippoglossus stenolepis, 

 Nautichthys oculofa^ciatus, Radulinus vinculiis, 

 Sebastes nebulosics, Stichaeopsis'? sp., Synchirus gilli) 

 are temperate and 10 {Alloclinus holderi, Caranx 

 caballus, Chaenopsis alepidota, Cryptotrema coral- 

 linum, Gibbonsia erythra, Gnathephis catalinensis, 

 Gobiesox rhessodon, Leiocottus hirundo, Mobula 

 japonica, Paraclinus integrippinis) are subtropical 

 or tropical. With only one exception (Radulinus virv- 

 cuhis), species on the list typical of the Oregonian 

 Province have their southern limit about San Miguel 

 or Santa Rosa, while most southern forms are 

 limited to Anacapa and Santa Cruz. 



Around Anacapa and the eastern end of Santa 

 Cruz, six species [Ophiodon elongatus, Sebastes 

 caurinus, S. miniatu^, S. mystinus, S. paucispinis, 

 S. serranoides) found in shallow water (0-36 m) to 

 the west were more abundant over deeper (37-72 m) 

 reefs. This is an example of "isothermic submer- 

 gence" (Briggs 1974). Discussing the mainland 

 southern California fish fauna, Briggs noted that 

 cooler preferring, temperate species sought deeper, 

 cooler waters in the warmer parts of their ranges. 

 All six species are temperate forms, all are found in 

 shallower waters off central California than along 

 the mainland of the Southern California Bight. 

 ' The increased length of four rockfishes (Sebastes 

 caurinus, S. mystinus, S. paucispinis, S. ser- 

 ranoides) in shallow water around the western 

 islands is at least partially due to a variant of iso- 

 thermic submergence. Among rockfishes, juveniles 

 are more eurythermic than adults (Miller and Geibel 

 1973; Love 1978), favoring shallower, warmer 

 waters. Juveniles of these four species were found in 

 shallow waters along all the islands (though in 

 decreasing abundance toward the warmer east), 

 while adults were abundant in shallow waters only in 

 the cooler, more westerly part of the island chain. 



Might the trend toward decreased mean sizes in 

 the eastern section be, in part, due to relatively high 

 fishing pressure? There are no records of total fish- 

 ing effort, stratified by depth, around these islands. 

 However, the California Department of Fish and 

 Game does have data on total angler-hours within 

 each block, derived from operator log-book records. 

 We present these data for 1975-78 in Table 5. It is 



Table 5. — Partyboat effort about the northern Channel 

 Islands, 1975-78. 



249 



