Seasonal and interannual variation in the abundance and demographics of the Pacific Sand Lance (Ammodytes personatus) in the San Juan Channel

The Pacific Sand Lance Ammodytes personatus is a small, semi-demersal forage fish that plays a crucial role in the pelagic ecosystem of the Salish Sea. Despite their important trophic function, little is known about the Pacific Sand Lance relative to other local forage fish species, due to the absence of a commercial fishery for sand lance in the Pacific Northwest. Our objective for this study was to characterize the populations of Pacific Sand Lance in two different habitats during the fall of 2015: the nearshore habitat of Jackson Beach, a known spawning beach, and the offshore habitat of the San Juan Channel sand wave field. To this end, we investigated several aspects of Pacific Sand Lance population structure, including their relative abundance, condition, and age structure over both seasonal and interannual timescales. Our findings were consistent with previous studies suggesting that Jackson Beach is likely a rearing habitat for young-of-the-year sand lance, while the San Juan Channel population is dominated by fish that are one and two years old. Our findings also suggest that sand lance may undergo winter reset in their condition each year. Finally, our ongoing time series has provided evidence that sand lance may experience interannual cyclic fluctuations in population structure. The emergence of these novel interannual trends in Pacific Sand Lance population structure underscores the necessity of long-term studies of ecologically important species in the Salish Sea