Patterns and influences on Dolly Varden migratory timing in the Chignik Lakes, Alaska, and comparison of populations throughout the northeastern Pacific and Arctic oceans

摘要

Dolly Varden (Salvelinus malma) are a facultatively anadromous salmonid common around much of the North Pacific Rim, but little is known about the environmental factors affecting the timing and diversity of their migration. We combined telemetry of anadromous fish with long-term monitoring of Dolly Varden upstream migration timing and environmental data in the Chignik Lakes watershed in Alaska and then compared the timing data with that of other streams where only count data were available. Telemetry revealed two upstream migration modes: midsummer and late fall at the Chignik Lakes. Weir counts indicated that timing fluctuated markedly over the monitoring period (1996-2011) and was negatively correlated with June sea surface temperature. The relationship between sea surface temperature and migration timing in other watersheds with long-term records was as follows: negative (Buskin River), positive (Auke Creek), or nonexistent (Goodnews and Kanektok rivers). Among 18 streams and rivers throughout the eastern Pacific range of Dolly Varden, median upstream migration date increased with latitude. Overall, Dolly Varden migration timing is more variable, protracted, and more strongly influenced by local sea surface temperatures than is typical of semelparous salmonids. These results are likely indicative of other iteroparous salmonids in Pacific waters that share similar environments and life-history characteristics.