DeMARTINI ET AL: DISTRIBUTION PATTERNS OF QUEENFISH 



Neomysis kadiakensis, a mysid more abundant at 

 depths corresponding to those frequented by adult 

 queenfish at night (Clutter 1967; Bernstein and 

 Gleye^), was a nontrivial component of the diet of 

 adult queenfish that ranked third by weight in 

 both males and females (although <1% of the total 

 IRI for each sex). None of the immature queenfish 

 that we sampled, however, had eaten any A^. 

 kadiakensis, even its juvenile stages (which also 

 occur offshore, Bernstein and Gleye footnote 9). 

 Nearshore prey, such as L. trispinosa and the de- 

 mersal meroplankter, D. tenuis, were generally 

 more important by weight and frequency of occur- 

 rence, if not numbers, in the diet of immature 

 versus adult queenfish (Table 4). The tendency for 

 immatures to remain closer to shore than adults 

 and to feed on meroplankton (that are more abun- 

 dant in sheltered areas closer to shore) has been 

 noted for many species of nocturnal zooplank- 

 tivorous fishes on tropical coral reefs (Hobson and 

 Chess 1978). 



Both immature and adult queenfish are concen- 

 trated nearshore during the day, probably in re- 

 sponse to pressure from diurnal predators (Hobson 

 1978; Allen and DeMartini 1983). Several species 

 of voracious carnivores including Pacific mack- 

 erel. Scomber japonicus; Pacific bonito, Sarda 

 chiliensis (Allen and DeMartini 1983); and 

 California halibut, Paralichthys californicus, of 

 piscivore-size (Plummer et al. 1983) are less abun- 

 dant nearshore in the San Onofre-Oceanside re- 

 gion. The California halibut is a known predator of 

 queenfish (Frey 1971; Plummer et al. 1983). The 

 kelp bass, Paralabrax clathratus, another species 

 known to prey on queenfish (Young 1963; E. De- 

 Martini^®), is most abundant in and near beds of 

 giant kelp, Macrocystis pyrifera, that occur at 

 10-15 m bottom depths in the region (Larson and 

 DeMartini 1984). 



Overall, our data indicate that the nocturnal 

 offshore dispersal of adults and the less contagious 

 distribution of immatures nearshore at night are 

 primarily for feeding. Allen and DeMartini (1983) 

 reviewed and discussed the possible advantages of 

 dispersal for feeding in schooling, zooplank- 

 tivorous fishes. To these we add the possible 

 benefit (for adult queenfish) of foraging in regions 



where M kadiakensis, a species of large mysid, is 

 more abundant. It is also likely that the rate at 

 which individual queenfish encounter planktonic 

 prey is enhanced by foraging in regions farther 

 offshore, where longshore currents are, on aver- 

 age, stronger (Reitzel"). 



The nighttime, nearshore distribution of small 

 immature queenfish also may be due to either or 

 both of the following factors. First, small queen- 

 fish are undoubtedly incapable of making as ex- 

 tensive diel migrations as adults because of body 

 size limitations. Hence the nearshore daytime dis- 

 tribution of immatures, probably set primarily by 

 the influence of diurnal predators offshore, might 

 limit the offshore movements of immatures at 

 night. Second, predation pressure from nocturnal 

 predators located farther offshore could restrict 

 immature queenfish to nearshore regions. Poten- 

 tial nocturnal predators of immature queenfish 

 include California halibut (Allen 1982) and 

 California scorpionfish, Scorpaena guttata (Hob- 

 son et al. 1981). The nocturnal habits of other po- 

 tential predators (Pacific mackerel. Pacific bonito, 

 and Pacific barracuda, Sphyraena argentea) of 

 small, immature queenfish are unknown. Large 

 (>70 mm SL, Fig. 3) immature queenfish move 

 offshore to some extent at night, which is also 

 consistent with offshore dispersal to feed on larger 

 prey, since size of prey is strongly related to 

 queenfish body size (Tables 4, 6). Offshore disper- 

 sal of large immatures is nonetheless consistent 

 with relaxed predation pressure, since susceptibil- 

 ity to predation must be inversely proportional to 

 body size. 



Rigorous evaluation of offshore dispersal for 

 spawning would require censuses of the onshore, 

 offshore distribution of recent spawning products. 

 However, we are at present unable to routinely 

 distinguish queenfish eggs or yolk-sac larvae 

 <2.2-2.3 mm long (~4 d old or less) (Watson^'^). 



In summary, we conclude that, as might be ex- 

 pected, the distributional (including migration) 

 patterns of queenfish have feeding, predator 

 avoidance, and perhaps other functions such as 

 breeding. 



'Bernstein, B. B., and L. G. Gleye. The ecology of mysids in 

 the San Onofre region. A study submitted to the Marine Review 

 Committee of the California Coastal Commission, April 30, 

 1981. Unpubl. rep., 72 p. Marine Ecological Consultants of 

 Southern California, 531 Encinitas Boulevard, Encinitas, CA 

 92024. 



'"E. DeMartini, Marine Science Institute, University of 

 California, Santa Barbara, CA 93106. Unpubl. data. 



"J. Reitzel. 1979. Physical /chemical oceanography. In 

 Interim Report of the Marine Review Committee of the Califor- 

 nia Coastal Commission. Part II: Appendix of Technical Evi- 

 dence in Support of the General Summary, March 12, 1979, p. 

 6-23. Unpubl. rep. Marine Review Committee Research 

 Center, 531 Encinitas Boulevard, Suite 106, Encinitas, CA 

 92024. 



'^W. Watson, Marine Ecological Consultants of Southern 

 California, Inc., 531 Encinitas Boulevard, Suite 110, Encinitas, 

 CA 92024, pers. commun. May 1983. 



183 



