Distribution of bocaccio (Sebaste paucispinis) and cowcod (Sebastes levis) around oil platforms and natural outcrops off California with implications for larval production

Abstract

There is increasing evidence that some California oil platforms form important
habitats for a number of economically important fishes. We asked to what extent
might platforms be important as producers of larvae of several overfished species
(bocaccio, Sebastes paucispinis Ayres, 1854 and cowcod, Sebastes levis Eigenmann
and Eigenmann, 1889) on a local or regional basis. We compared adult densities
and potential larval production of these species at platforms and natural outcrops
in California. Densities of mature bocaccio and cowcod were highly variable among
survey sites, but were generally very low at both natural reefs and platforms. However,
the mean densities for both species were higher around platforms than at natural
reefs. Two of the three platforms (Gail and Hidalgo) that harbored mature bocaccio
had larger mature individuals than did any natural reef. Platform Gail had by far
the highest densities of both mature bocaccio and cowcod of any natural or human-
made habitat and the potential larval production of both species at Platform
Gail was much higher than at any other site surveyed. We estimated the removal of
Platform Gail would be the equivalent of removing 12.57 ha of average-producing
natural habitat in southern California for cowcod or 29.24 ha of average-producing
natural habitat for bocaccio. These results may have implications for the platform
decommissioning process.