In marine systems, non-native species are usually introduced by accident. Many marine species have a larval-like life stage during which they swim or float in the water column. These organisms can be transported by ballast water, which ships store in large tanks. Species can also be transported by attaching themselves on hard, wetted surfaces such as hulls, propellers, and anchors. We refer to this mechanism as “fouling”. As ships travel from one port to another, they can transport fouling and ballast water organisms thousands of miles and inadvertently introduce them to new regions. Understanding where ships are coming from and where they are arriving can allow us to identify potential ports of introduction for non-native species into the Bering Sea.
We described shipping patterns for commercial and fishing vessels arriving in Bering Sea ports between 2014 and 2016. These two vessel types constitute most of the shipping traffic in the Bering Sea.
Data from: National Ballast Information Clearinghouse
Data from: NOAA Vessel Monitoring System
Dutch Harbor received the greatest amount of traffic from both commercial and fishing vessels. Nome received the second highest amount of traffic from commercial vessels, and Akutan ranked second for fishing vessel traffic. Most commercial vessels originated from outside the state of Alaska, with California, Washington, and South Korea accounting for most of the traffic. In contrast, most fishing vessels originated from ports in the Gulf of Alaska.