Juvenile Rockfish Recruitment in Trinidad Bay, California

Abstract

This study is the first to describe the relative interannual abundance and timing of nearshore juvenile rockfish, Sebastes spp., recruiting to nearshore kelp beds in Trinidad Bay, California. Recruitment refers to the number of individuals arriving onshore from pelagic larval habitat. Documenting recruitment at new sites may provide insight into coastwide patterns, providing resolution to competing hypotheses that describe why annual recruitment varies. However, recruitment can be patchy along the coast, requiring exploratory research to identify recruitment sites before beginning long-term monitoring. The objective of this study is to provide the first description of the timing and abundance of nearshore juvenile rockfish entering kelp beds in Trinidad Bay. Fish were sampled weekly over the summers of 2010 and 2011 with two artificial reefs, Standard Monitoring Units for the Recruitment of Fishes (SMURFs). The number of fish sampled varied annually, averaging 3,464 (n = 2, SD = 315) fish sampled per SMURF in 2010 and 447 (n = 2, SD = 8) sampled per SMURF in 2011. Of the fish sampled, 46% and 23% were juvenile Black Rockfish S. melanops in 2010 and 2011, respectively. The order in which species arrived onshore was consistent between the years and matched the order of parturition among species. We conclude Trinidad Bay would be a valuable site for long-term monitoring of rockfish recruitment in northern California and discuss our observations within the context of habitat selection, larval transport, and open-ocean survival.

Received August 25, 2013; accepted November 6, 2013

ACKNOWLEDGMENTS

Financial support for this project came from the following sources: the James Joseph Inter-America Tropical Tuna Association, the Boomer Esiason Foundation, The Golden West Women's Flyfisher Society, The Granite Bay Flycaster's Society, The Marin Rod and Gun Club, and the Malcolm Oliphant Marine Science Scholarship. Mooring buoys were provided by the Trinidad Rancheria. Affiliates of the University of California Santa Cruz, including Thomas Laidig, Arnold Ammann, Karah Ammann, and Alex Macleod, assisted in designing SMURFs and fish identification. Additional thanks to Arnold Ammann for reviewing an earlier draft of this manuscript and to Cedar Morton for creating the map of Trinidad Bay.