Determinants of stream life, spawning efficiency, and spawning habitat in pink salmon in the Auke Lake system, Alaska

Variation in stream life, spawning efficiency, and spawning habitat among adult pink salmon (Oncorhynchus gorbuscha) in the Auke Lake system, southeastern Alaska, was best explained by stream discharge, stream temperature, and a combination of stream temperature and discharge. We estimated these attributes of female pink salmon spawners in samples of daily cohorts tagged as they entered fresh water and used generalized linear models to analyze variation in the attributes with respect to environmental factors. Spawners varied in stream life (5-11 days), spawning efficiency (30-70% of females in daily entry cohorts retained less than 500 eggs at death), and spawning habitat (30-70% spawned in the lake outlet stream rather than the lake inlet stream). Observed variation of habitat (proportionately more use of the cooler inlet stream early in the spawning season when stream temperatures are warm and development is rapid) would contribute to synchronicity of fry emigration, which is known to be positively correlated with subsequent survival in Auke Lake pink salmon.