Ms. Jessica Freeman1, Prof. Brice Semmens1, Dr. Andrew Thompson2
1Scripps Institution Of Oceanography, UC San Diego, La Jolla, United States, 2NOAA Fisheries Service, Southwest Fisheries Science Center, La Jolla, United States
Although it is well established that Marine Protected Areas (MPAs) are effective tools for augmenting the abundance of fished species, effects on biodiversity and community structure are less clear. Many rockfish species were overfished in the California Current Ecosystem at the turn of the 21st century, and establishment of two large MPAs in the Southern California Bight, the Cowcod Conservation Areas (CCAs), alongside environmental conditions that facilitated spawning and recruitment, helped rebuild overfished rockfish stocks by 2019. We evaluated the impacts of the CCAs and environment on rockfish diversity and assemblage structure using a 16-year time series (1998-2013) of genetically-identified rockfish larvae. We found that while rockfish richness generally increased across the time series, the greatest increases occurred inside CCAs when temperature was low and dissolved oxygen high. We also found a clear species assemblage shift after the 2001 CCA implementations driven largely by increased presence/abundance of rockfishes targeted by fisheries. The 2002 change in assemblage structure was most likely initially driven by the maturation of a strong 1999 year class and sustained by protection from fishing and favorable environmental conditions. Our results suggest that the large and sustained MPAs along the southern California coast have induced increases in the diversity of rockfish reproductive output, driven largely by the direct effects of fishing cessation on targeted species.
Presentation Slides – Brice Semmens
Biography:
Dr. Brice Semmens is a Professor at Scripps Institution of Oceanography, UC San Diego, and is the Director of the California Cooperative Oceanic Fisheries Investigations (CalCOFI) program. CalCOFI is the world’s longest running ocean ecosystem monitoring program. Dr. Semmens’ research interests include quantitative ecology, fisheries and conservation, and climate impacts on oceanography.
