Ecological performance of young-of-the year blue rockfish (Sebastes mystinus) associated with oil platforms and natural reefs in California as measured by daily growth rates.

Abstract

Decommissioning alternatives regarding offshore oil platforms include leaving some or all of the platform structure in place. However, despite the high numbers of fishes that can reside around offshore platforms, little is known about the comparative ecological performance of fishes living on platforms compared to those inhabiting natural habitats. It would be expected that sites where fishes exhibited better growth, increased reproduction, or greater survival rates would be beneficial to regional fish populations. We determined and compared the birthdate distributions and daily growth rates of 116 young-of-the-year (YOY) blue rockfish (Sebastes mystinus Jordan and Gilbert, 1881) among two platforms and two natural reefs in the Santa Barbara Channel region. We found a significant though modest lunar pattern in birthdates where blue rockfish produced (or successfully recruited) more larvae in the week leading up to the full moon. Mean growth rates were significantly different across sites. At one of the two site pairs (platform-natural reef), YOY rockfish growth rates were significantly higher at the platform habitat; there was no statistical difference in growth rates between fish living at the other site pair. This study demonstrates that, as measured by daily growth rates, blue rockfish living around oil and gas production platforms may perform at least as well as those fish living on natural reefs, and supports previous research implying that some platforms may benefit regional fish populations.