Valle et al.: Habitat use by Paralichthys cahfornicus and Paralabrax nebulifer 



657 



found that initial settlement patterns for some fishes 

 in seagrass beds were altered considerably by move- 

 ment to other areas. Our results indicate that this may 

 be also true for barred sand bass because significantly 

 larger fish were found at Belmont Shore, indicating 

 that movement to this site from the site nearest the 

 entrance after initial settlement may have occurred. 

 However, we are not able to resolve why barred sand 

 bass were absent from the inner part of the bay. 



Densities of newly settled and juvenile California 

 halibut in our study were much greater than those 

 reported by others using similar gear in other bays. 

 Kramer (1990) obtained maximum monthly means 

 for shoreline habitats in Agua Hedionda Lagoon of 

 3.7 newly settled California halibut per 100 m-^ for 

 all stations combined and 9.2 per 100 m' for a single 

 station. These densities are approximately 25'7f and 

 11"^, respectively, of the values we obtained for 

 Alamitos Bay. Our maximum monthly mean num- 

 ber of newly settled California halibut was approxi- 

 mately four times greater than that obtained for 

 nearby Anaheim Bay in 1989 (Allen and Herbinson, 

 1990). Thus, our results support the conclusion by 

 Allen and Herbinson ( 1990) that there is a great deal 

 of annual variability in numbers of newly settled and 

 juvenile California halibut within and among 

 embayments in southern California. 



Although the beam trawl may capture demersal 

 fishes such as California halibut less effectively in 

 eelgrass beds than in unvegetated areas, this seems 

 an unlikely explanation for the great differences in 

 habitat specific fish abundances that we observed. 

 First, we collected large amounts of eelgrass blades 

 (occasionally with attached rhizome) in many tows, 

 and SCUBA observations indicated that the beam 

 trawl maintained continuous contact with the sub- 

 strate in both habitats. Second, staghorn sculpin, 

 which rest on the substrate, and shadow goby, which 

 often burrow in the sediment, were frequently cap- 

 tured in both habitats. Because we collected data only 

 at low tides during daylight hours, we have no infor- 

 mation on how sampling at different tide heights and 

 times of the day would have affected our results. Diel 

 differences in fish abundance can occur in southern 

 California bays (Horn, 1980; Hoffman^); however, 

 there are no data to suggest that these differences 

 are related to habitats or locations within the bay. 



Other species 



Alamitos Bay was typical of other temperate bay- 

 estuarine environments in having relatively few spe- 

 cies account for a large proportion of the total num- 

 ber of individuals collected (reviewed in Allen and 

 Horn, 1975: Horn, 1980; Allen, 1982; Onuf and Quam- 



men, 1983; Allen and Herbinson, 1991; Hoffman-*; MBC 

 Applied Environmental Sciences'^). Species composition 

 and abundance were very similar to data collected us- 

 ing similar gear in Anaheim Bay and Agua Hedionda 

 Lagoon (Allen and Herbinson, 1991; MBC Applied En- 

 vironmental Sciences''). Our results, however, lacked 

 high abundances of northern anchovy (Engraulis 

 nwrdox), slough anchovy (Anchoa delicatissima), 

 deepbody anchovy (Anchoa compressa ), and California 

 killifish iFuiidulus pafvipinnis) found by other stud- 

 ies in the inner part of Alamitos Bay and Newport Bay 

 (Allen and Horn, 1975; Allen, 1982). Differences in sam- 

 pling gear and location are probably responsible, but 

 other factors may also play a role. As noted by Allen 

 and Horn ( 1975), the abundance of northern anchovy 

 may have been due to high periods of recruitment. In- 

 deed, recruitment biomass of northern anchovy (age 

 zero at 1 July ) off southern California during their stud- 

 ies (1973 and 1979) was 2.6-3.1 times greater than 

 during 1992-94 ( Jacobson et al.*^) 



For most species, greater abundances of individu- 

 als in either eelgrass or unvegetated areas suggested 

 habitat preferences or differential mortality for these 

 species in shallow water of Alamitos Bay. The large 

 numbers of species and individuals in eelgrass beds 

 indicated the importance of this habitat for many 

 fishes, especially juveniles during spring and sum- 

 mer. Many of the fishes also differed in abundance 

 across sites. More species were found near the bay 

 mouth owing in part, to the occasional presence of 

 more typical nearshore residents, but more individu- 

 als of several species were found farther inside the 

 bay. However, the differences in eelgrass physical 

 characteristics among sites did not appear to affect 

 the abundances of most fishes. For example, abun- 

 dances of bay blenny, bay pipefish, and shadow goby 

 were not significantly different between Bay En- 

 trance and Belmont Shore, although eelgrass den- 

 sity and blade lengths were significantly different 

 between these sites. In addition, giant kelpfish and 

 spotted kelpfish were most abundant at Belmont 

 Shore, the site with the lowest eelgrass density and 



'' Hoffman, R. S. 1986. Fishery utilization of eelgrass (Zos^era 

 marina) beds and non-vegetated shallow water areas in San 

 Diego Bay. National Marine Fisheries .Service, Southwest Re- 

 gion. .50"l W. Ocean Blvd. Suite 4200. Long Beach. CA. 

 90802. Admin. Rep. SWR-86-4, 29 p. 



^ MBC Applied Environmental Sciences. 1990. Distribution of ju- 

 venile California halibut iPaj-alichthys californicus) and other 

 fishes in bay and coastal habitats of Los Angeles, Orange, and 

 San Diego counties in 1989. MBC Applied Environmental Sci- 

 ences, 947 Newhall Street. Costa Mesa, CA 92627. Final Rep. 

 90-RD-09. 27 p. 



*^ Jacobson. L. D.. N. C. H. Lo. S. F Hemck Jr. and T. Bishop. 1995. 

 Spawning biomass of the northern anchovy in 1995 and status of 

 the coastal pelagic fishery during 1994. Southwest Fisheries 

 Science Center. National Marine Fisheries Service. NOAA, P. O. 

 Box 271, La Jolla, CA 92038. Admin. Rep. U-95-11, 49 p. 



