Assessing the effects of changes in reproductive condition on the survival of anadromous Dolly Varden ( <i>Salvelinus malma</i> ) using Bayesian multistate capture–recapture modelling

Understanding the interrelationship between the survival and reproductive states of salmonids is important for both management and conservation purposes; however, their complex life history introduces challenges. The survival probabilities of anadromous Dolly Varden ( Salvelinus malma) are influenced by their reproductive cycle, while predicting their reproductive state in successive years is difficult as it can vary based on an individual’s sex. We developed a Bayesian multi-state capture–recapture model that estimates reproductive state transition probabilities, survival probabilities, and the effect of sex on state transitions using the Cormack–Jolly–Seber model. We applied the model to Dolly Varden data collected from five river systems in the western Canadian Arctic. We demonstrate sex-specific state transition probability differences, with females exhibiting higher transition rates into reproductive states. Moreover, survival probabilities were influenced by both sex and reproductive status. Across all rivers, survival probabilities for both sexes decreased by approximately 50% while spawning compared to non-spawning. This study provides important insights into how reproduction and sex affect survival among stocks, which improves their assessment to ensure management and conservation goals.