The Channel Islands and Monterey Bay National Marine Sanctuaries seek to preserve the biodiversity, cultural history, scenic beauty, and economic productivity of California’s most precious ocean treasures. Both sanctuaries are visited annually by a plethora of migratory cetaceans, pelagic fish, and seabirds. Unfortunately, oceans are facing increasing anthropogenic pressures, and noise pollution is a growing concern. Exposure to acute sound sources poses a significant risk to acoustically sensitive cetacean species protected under the Marine Mammal Protection Act and the Endangered Species Act.

This project will provide a targeted analysis of the acoustic impacts of a legal marine mammal acoustic deterrent known as a “seal bomb”. These deterrents are underwater explosives used in purse seine fisheries, such as the California market squid fishery, to deter marine mammals from interfering with commercial fishing operations. Seal bombs alter the natural ocean soundscape and are believed to cause indirect acoustic impacts to cetaceans within the same vicinity. Therefore, this project will analyze squid fishing dynamics and associated seal bomb use through passive acoustic monitoring systems within both sanctuaries. Spatial overlap between recorded seal bomb explosions and existing cetacean habitat distribution  will elucidate times and regions where cetaceans may be experiencing increased risk. Our analysis will also assess the dynamics of seal bomb use by overlaying squid fishing activity with confirmed seal bomb detonations.

We aim to provide recommendations to the National Marine Fisheries Service, Office of National Marine Sanctuaries, and the State of California by outlining best management practices to mitigate the impact on cetaceans within Monterey Bay and Channel Islands National Marine Sanctuaries, highlighting regions where seal bombs can be used with minimal impacts to marine organisms and where use should be monitored or restricted.

Data was provided from a variety of different sources:

• Squid Ticket Landings, California Department of Fish & Wildlife
• Seal Bomb Detections, NOAA SanctSound & Monterey Bay Aquarium Research Institute
• Fishing Vessel Detections, NOAA ONMS, model output from VIIRs Satellite Data
• Cetacean Distrubution Data, NOAA Fisheries
• Cetacean Biologically Important Areas, NOAA CetSound

Data was pre-processed to align spatial and temporal resolution of datasets and then analyzed using R, and ArcGIS.