Spatiotemporal Dynamics of Pacific Sand Lance (Ammodytes hexapterus) Populations in the San Juan Archipelago during Fall Season

Abstract

The Pacific sand lance (Ammodytes hexapterus) is an ecologically important forage fish in the Salish Sea serving as a link between secondary consumers and top predators. In this study we investigated variation in length, stomach fullness, condition factor, and catch per unit effort (CPUE) through the fall season in 2013 in order to infer the timing of overwintering dormancy. We also tested for differences between locations. Population structure and variation through the fall season were compared between populations at the San Juan Channel wave field and Jackson Beach and between past year’s findings (2006, 2010, 2012). The wave field population was significantly larger and was in greater condition than the population at Jackson Beach. Through the fall season for the wave field population: length remained stabled, stomach fullness remained stable, condition factor declined, and CPUE remained stable. For the Jackson Beach population: length remained stable, stomach fullness declined, condition factor remained stable, and CPUE decline. These results suggest an earlier shift into overwintering dormancy for the wave field population compared to Jackson Beach.