Hopf et al. (2022; preprint online at Ecological Applications) investigated the issue of year-to-year variability in the larval recruitment of kelp forest fishes, and how it affects how we assess the effectiveness of marine protected areas for conserving those fishes. Using a 20-year dataset, we found that a common kelp forest fish in southern California has periodic peaks and troughs in recruitment, with a ~6 year cycle. Then, using age-structured population models we found that whether a new marine protected area was put in place during a peak or a trough either enhanced or delayed (respectively) post-protected population increases. That makes it more difficult to determine whether the reserve is successfully enhancing the population. Helpfully we also found that using before-after control-impact designs for monitoring helped mitigate this issue.

This project is a product of the Partnership for the Interdisciplinary Study of Coastal Oceans, and we hope it will inform the assessment of marine protected areas in California and Oregon in 2023.

Email will.white@oregonstate.edu if you would like a copy of the manuscript.