University of California, Santa Barbara, United States
Abstract: The giant sea bass, Stereolepis gigas, is the largest bony fish found along the California coast and is an important apex predator in kelp forest and rocky reef ecosystems. Due to their slow growing nature and annual aggregative predictability, they were nearly fished to extinction throughout their entire range: Humboldt Bay to Baja California, Mexico. Now listed as critically endangered by the International Union for the Conservation of Nature (IUCN) and protected by a fishing moratorium in California, it is believed the giant sea bass (GSB) population is recovering. However, there has been no direct population assessment of their numbers in California. Through collecting community-sourced photos of GSB via the Spotting Giant Sea Bass Project (https://spottinggiantseabass.msi.ucsb.edu/), we have been able to identify unique individuals through their spot pattern using machine learning algorithms, as GSB have idiosyncratic markings on their flanks. To date, we have identified 500 left side individuals and 480 right side individuals out of 1050 verified GSB encounters from 110 community scientists. Through capture-mark-recapture population models, the GSB population is exhibiting signs of recovery. Additionally, GSB seem to have high site fidelity with the majority of GSB being resighted at the same dive site. Assessing GSB population trends allows for evaluating current conservation efforts and with a better understanding of their spatial patterns, more effective conservation management strategies can be proposed incorporating spatial and temporal elements. These efforts may further help the recovery of GSB thus increasing population resiliency, ecosystem function, and improving local ecotourism as each GSB is valued at $2.3 million to recreational divers annually.
