By Tristin McHugh, Reef Check California North Coast Manager
Reef Check California’s North Coast Kelp Forest Restoration project has begun! Since 2014, bull kelp in northern California, primarily along the Sonoma and Mendocino county coastline, has declined more than 90% due to a combination of extreme warm water events and multiple ecological stressors, including significant increases in purple sea urchin populations, which feed upon the kelp. This has led to a large-scale shift from bull kelp forests to urchin barrens across most of the region. This shift has caused significant losses of kelp forest biodiversity and ecosystem services, resulting in the collapse of the North Coast commercial red urchin fishery ($3 Million ex-vessel value) beginning in 2015 and the closure of the recreational red abalone fishery (estimated at $44 Million non-market value) in 2018.
Earlier this month, Reef Check and partners began to remove purple urchins (Strongylocentrotus purpuratus) from a restoration area in North Noyo Harbor, Fort Bragg (Caspar Cove is the next site this effort will target). The goal of this collaborative project is to ultimately catalyze a phase shift from urchin barren to kelp forest on targeted reefs. Furthermore, we are assessing if purple urchin densities can be reduced and maintained over time to allow kelp to grow and serve as a kelp oasis, providing spores (kelp seeds) to surrounding areas. This project will play a vital role in determining how resource managers choose to move forward with kelp restoration strategies statewide, thus helping to evaluate the costs and benefits of human intervention in a dynamic oceanic environment.
Prior to urchin removal efforts, Reef Check divers collected ecosystem information (such as fish, invertebrate and algae densities) to get a picture of what reefs looked like at the time at which restoration began in areas to be restored and in other areas that will not be touched. Following the removal of urchin, Reef Check divers will conduct quality control surveys to assess the effectiveness of the effort and ecosystem surveys to compare reefs before and after restoration with reefs that will not be restored. Making these comparisons will allow us to evaluate the outcome of the restoration efforts. This provides Reef Check and managers with the information necessary to help guide where resources and urchin removal efforts are most needed and effective.
After urchins are removed from the restoration area, they are taken back to Noyo Harbor where Reef Check staff and volunteers further process the urchins and measure a number things such as weight and size of urchins and bycatch to better understand the methods used to remove urchin and also investigate the biology of the urchin occupying the reef. Stay tuned in the coming year as we further develop this program (Funding Source: Ocean Protection Council).