Author: Natasha Benjamin, Marine Research and Exploration (MARE)
Sea cucumbers are an important component of the sub-tidal zone, feeding on benthic waste and recycling nutrients. They are the “earth worms” of the seafloor. Similar to other sea cucumber fisheries around the world, demand is increasing in California, while the resource is becoming less abundant. MARE joined forces in a unique partnership with the California Department of Fish & Wildlife (CDFW) the National Park Service, and commercial sea cucumber fishermen to understand more about these critters.
This collaborative research project gathered information to inform the management of the warty sea cucumber (WSC) commercial dive fishery in California’s northern Channel Islands. The project brought together commercial fishermen, a deep diving robotic submarine and state and federal agency biologists to gather data and identify strategies to sustainably manage the warty sea cucumber fishery.
Ongoing SCUBA density surveys conducted by CDFW and the National Parks Service have documented differences inside and outside of protected areas, with WSC much less abundant in fished areas. In addition, a seasonal differential was also documented, with the highest WSC densities observed during spring spawning periods and the lowest densities occurring in the fall.
Anecdotal reports from the commercial dive fishery have suggested that WSCs undergo a seasonal migration from deep to shallow waters in spring, but the degree to which WSCs utilize deeper waters during this spring spawning period remained unknown. This information was needed to determine the role that deeper areas play in supporting WSC populations, since areas beyond SCUBA diver depth have historically been considered to provide an element of deep-water refuge. To research this, MARE and CDFW conducted a deep water ROV expedition to better understand the seasonal abundance inside and outside of protected areas and to examine seasonality of abundance in these deeper depths.