English Sole Spawning Migration and Evidence for Feeding Site Fidelity in Puget Sound, U.S.A., with Implications for Contaminant Exposure

Abstract

English sole is used as a sentinel species for contaminant studies in Puget Sound because it is abundant, easily sampled, and broadly distributed in the northwestern United States. Moreover, this species exhibits a number of well-documented effects of polycyclic aromatic hydrocarbon (PAH) exposure. To assess the potential for contaminant exposure during spawning migrations and to track the localized movements of adult English sole in the vicinity of Eagle Harbor, we used acoustic telemetry. In August 2007, we collected 19 English sole from Eagle Harbor, a small embayment of Puget Sound with a long history of PAH contamination and subsequent remediation actions. Fish were surgically implanted with uniquely-coded acoustic transmitters and their movements were tracked via an array of eight submersible receivers inside Eagle Harbor and near its entrance. In addition, we obtained detection data from over 70 other receivers throughout Puget Sound that were maintained by a consortium of regional researchers. All tagged fish were detected immediately after release, and 18 were detected outside of Eagle Harbor at a variety of locations in Puget Sound. Some of these fish made rapid movements across the sound and traveled minimum distances of 32 to 106 km. Half of the fish detected outside Eagle Harbor returned to their capture site in spring 2008, approximately eight months after tagging. This fidelity to summer feeding habitats has important implications for both contaminant studies and flatfish management. In addition, our results illustrate the power of data sharing and the value of pooling resources to maintain large arrays of acoustic receivers.