383 



Abstract — Although bocaccio iSe- 

 bastes paucispinis) was an economi- 

 cally important rockfish species along 

 the west coast of North America, 

 overfishing has reduced the stock 

 to about TAVc of its former unfished 

 population. In 2003, using a manned 

 research submersible, we conducted 

 fish surveys around eight oil and gas 

 platforms off southern California as 

 part of an assessment of the potential 

 value of these structures as fish habi- 

 tat. From these surveys, we estimated 

 that there was a minimum of 430,000 

 juvenile bocaccio at these eight struc- 

 tures. We determined this number to 

 be about 20% of the average number 

 of juvenile bocaccio that survive annu- 

 ally for the geographic range of the 

 species. When these juveniles become 

 adults, they will contribute about 

 one percent (0.8%) of the additional 

 amount offish needed to rebuild the 

 Pacific Coast population. By compari- 

 son, juvenile bocaccio recruitment to 

 nearshore natural nursery grounds, 

 as determined through regional scuba 

 surveys, was low in the same year. 

 This research demonstrates that a 

 relatively small amount of artificial 

 nursery habitat may be quite valuable 

 in rebuilding an overfished species. 



Potential use of offshore marine structures 

 in rebuilding an overfished rockfish species, 

 bocaccio (Sebastes paucispinis) 



Milton S. Love^ 



Donna M. Schroeder' 



William Lenarz^ 



Alec MacCalP 



Ann Scarborough BulH 



Lyman Thorsteinson^ 



' Marine Science Institute, University ol California 

 Santa Barbara, Calilornia, 93160 

 E-mail address (for M, S. Love: ioveia'lifesci.ucsbedu 



2 P.O. 251 



Kentlield, California 94914 



3 NOAA/NfVIFS Santa Cruz Laboratory 

 Santa Cruz, California 95060 



" U.S. Minerals Management Service 

 770 Paseo Camarillo 

 Camarillo, California 93010 



^ Western Fisheries Research Center 

 U.S. Geological Survey 

 6505 NE 65'^' St 

 Seattle, Washington 98115 



Manuscript submitted 2 September 2005 

 to the Scientific Editor's Office. 



Manuscript approved for publication 



26 September 2005 by the Scientific Editor. 



Fish. Bull. 104:383-390 (2006). 



Beginning in 1995, annual surveys of 

 fish assemblages at oil and gas plat- 

 forms and natural reefs throughout 

 southern California were conducted 

 with a research submersible (summa- 

 rized in Love et al., 1999, 2000, 2003). 

 Many California oil and gas platforms 

 harbor three fish assemblages: those 

 that occupy the shell mound area sur- 

 rounding the base of the platform; 

 those that occupy the waters adja- 

 cent to the platform bottom, and those 

 that occupy the midwater. Rockfishes 

 (genus Sebastes), of about 35 spe- 

 cies, dominate these assemblages. 

 The shell mound assemblage is com- 

 posed primarily of juvenile rockfishes, 

 dwarf rockfishes, and other species; 

 the platform bottom assemblage is 

 composed of adult and subadult fishes; 

 and the midwater assemblage of most 

 platforms (and the bottoms of some 

 mid-depth platforms) is dominated 

 by young-of-the-year (YOY) and older 

 juvenile rockfishes that comprise at 

 least 28 species. These fishes are 

 rarely more than 20 cm long (total 



length). In the midwaters of most Cal- 

 ifornia platforms, there are only low 

 densities of predatory reef fish species, 

 such as kelp bass (Paralabax clath- 

 ratus) and cabezon (Scorpaenichthys 

 marmoratus), or semipelagic, large 

 predatory species, such as Pacific bar- 

 racuda (Sphyraena argentea) and yel- 

 lowtail (Seriola lalandi). The proper 

 disposition of the approximately 6000 

 marine offshore oil and gas platforms 

 and associated structures now in ser- 

 vice worldwide is in dispute. There 

 are 27 platforms off California and, 

 as in other parts of the world, there is 

 considerable debate over the ultimate 

 fate of these structures once they are 

 uneconomical to operate (Schroeder 

 and Love, 2004). In this article, we 

 focus on the role that some artificial 

 structures play as rockfish nursery 

 habitat off California. 



During some years, we have noted 

 particularly high densities of YOY bo- 

 caccio {Sebastes paucispinis), widow 

 (S. entomelas), squarespot (S. hop- 

 kinsi), and blue (S. mystinus) rock- 



