NOTES Love and Westphal Fish populations around oil platforms off Santa Barbara, California 



605 



In review). Their subadults make ontogenetic shifts into 

 deeper water. Secondly, fishing pressure around the 

 platforms probably crops many larger individuals. 

 Lastly, it is possible that artificial habitat in some 

 unknown way discourages adult rockfish. F. Matthews 

 (Dep. Oceans and Fish., Pacific Biol. Stn., Nanaimo, 

 B.C., Canada V9R 5K6, pers. commun.. May 1989) 

 found that only immature rockfish occurred on an ar- 

 tificial reef in Puget Sound. Natural reefs supported 

 both juveniles and adults. 



As discussed before, most rockfish species (including 

 S. entomelas and S. paucispims) recruit to shallow 

 water, then migrate into deeper zones as they mature. 

 Based on catch rates, we have noted on several occa- 

 sions that large aggregations of these species were 

 present around the platforms for months, only to sud- 

 denly disappear. Hartmann (1987) tagged juvenile S. 

 paucispinis around these platforms and noted recov- 

 eries from as much as 148 km away. In all cases the 

 fish were taken in water considerably deeper than tag- 

 ging depths. Thus, it is quite possible that some rock- 

 fish species settle out around these platforms, live there 

 for a few years, and leave for deeper adult habitats, 

 perhaps at considerable distances from the original 

 recruitment site. 



Conclusions 



Platforms were important fishing locations for the 

 sportfishing party vessel surveyed. About 18% of its 

 total fishing time and 17% of the total catch occurred 

 around the platforms. This compares with about 21% 

 of fishing time and 31% of total catch at the nearby 

 natural reefs. Rockfish dominated the catch at both the 

 platforms and at the natural reefs. Confirming what 

 we had first observed, there were significant differ- 

 ences in catches between the platforms and natural 

 reefs. Juvenile rockfish composed most of the platform 

 catch, while mature rockfish were more abundant over 

 reefs. While midwater rockfish species were abundant 

 at both platform and natural reefs, species composi- 

 tions were different, with those benthic rockfish char- 

 acteristics of high-relief substrata absent or rare 

 around the platforms. 



This work was sponsored by NOAA, Office of Sea 

 Grant, U.S. Department of Commerce, under grant no. 

 04-7-158-44121 (Project r/f-39). 



Citations 



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Acl<nowledgments 



I thank Alfred W. Ebeling for reviewing this manu- 

 script. Fred Benko of Sea Landing Sportfishing graci- 

 ously allowed me space on the Hornet. I particularly 

 thank partyboat operators Chet Phelps, Irv Grisbeck, 

 Frank Hampton, George Kelly, and Dick Clift for mak- 

 ing sampling possible. 



