Batten down the hatches: Opportunities to protect Alaska from biological invasions through watercraft trade and traffic

Invasive species are spreading into northern latitudes and threatening food and water security. Alaska’s aquatic environments support some of the world’s most productive wild salmon fisheries. Yet, the influx of invasive species increases the strain on the ecosystems, cultures, and economies that depend on these fisheries. Especially worrisome is the potential transmission of aquatic invasive species (AIS) such as zebra mussels (Dreissena polymorpha), quagga mussels (Dreissena bugensis), or Asian clams (Corbicula fluminea) through the trade and traffic of recreational watercraft from AIS-infested regions. Since neither invasive mussels nor clams have been found in Alaska waters, there is opportunity to prevent introductions of invasive molluscs and avoid catastrophic impacts to some of the world’s last intact ecosystems. To date little data are available to guide human response to reducing the risk of transmitting freshwater AIS that affect critical natal habitat for Alaska’s salmon fisheries. This study triangulated existing data on watercraft registrations and inspections with key informant interviews to establish a first estimate of introduction rates for watercraft-related AIS. Results show that at least 129 used and motorized watercraft are estimated to enter Alaska annually from dreissenid-infested regions with an estimated 47 reaching Alaska freshwater uninspected. These watercraft are entering Alaska through both land and marine pathways. The study points toward the need for a collaborative response among state, federal, tribal, and local agencies, and watercraft owners to devise effective prevention. Response opportunities include inspections and decontaminations at critical control points, and an increased outreach and education campaign for watercraft users. Policy implications for salmon fisheries are discussed should AIS become established in Alaska. Also, the costs, and the long-term sustainability of a prevention program are discussed.