Salish Sea Ecosystem Conference

Monitoring the movements of a critical marine resource: tracking a forage fish in Puget Sound

Room 613-614

Forage fish are small, schooling, pelagic fish that form a critical link in marine food webs between plankton and larger fish, marine mammals, and seabirds. In Puget Sound, the forage fish assemblage includes Pacific herring, Pacific sand lance, surf smelt, and northern anchovy. There are significant information gaps on basic life history, distribution, movements, and stock abundances for these species, making management of this resource challenging. To begin addressing some of these gaps, we initiated a study of the movements of surf smelt during their spawning period in November 2012. We captured fish near a well-documented spawning beach in Sinclair Inlet (Ross Point), implanted them with acoustic transmitters, and monitored their movements around central Puget Sound. Inasmuch as telemetry studies have not previously been conducted for surf smelt, the goals of this initial effort were to: 1) assess methods to handle, anesthetize, and surgically implant acoustic transmitters into surf smelt, 2) describe the movements of tagged fish in Sinclair Inlet and Central Puget Sound, and 3) document the risk of recapture by recreational or commercial fishing effort in Sinclair Inlet. We collected, tagged, and released 12 adult smelt (mean 167 mm FL, 43 g) at Ross Point and implanted them with acoustic transmitters that had an expected battery life of 73 days. Study fish were given a secondary mark for easy visual identification, and we established a reward for the return of tagged fish captured through recreational or commercial fishing effort. We deployed 13 acoustic telemetry monitoring stations including near the spawning beach at Ross Point, Port Washington Narrows, Port Orchard, Rich Passage, Agate Passage, Liberty Bay and Eagle Harbor. In addition to these sites the tagged fish could have been detected by compatible acoustic telemetry stations deployed in Puget Sound by other agencies, for example, at Admiralty Inlet, the Strait of Juan de Fuca, and in the San Juan Islands. All study fish were detected within a few days of their release, suggesting that the fish handling, anesthesia, and tagging procedures that were developed for this species did not result in significant short-term mortality. Study fish were only detected at Ross Point (all individuals) and at the Port Washington Narrows (one individual). Although the reward program was well advertised and recreational fishing pressure at Ross Point was consistent throughout the study period, none of the tagged fish were returned through recreational or commercial fishers. More intensive monitoring of surf smelt movements in Sinclair Inlet is planned for 2014 to build upon this initial work.