6533b870fe1ef96bd12cef7e

RESEARCH PRODUCT

Age is not just a number – senescence affects how fish populations respond to different fishing regimes

subject

description

Abstract The presence of senescence in natural populations remains an unsolved problem in biology. Described as an age-dependent increase in natural mortality (known as actuarial senescence) and an age-dependent decrease in fecundity (known as reproductive senescence), the role of senescence in nature is still poorly understood. Based on empirical estimates of reproductive and actuarial senescence, we explored how senescence affects the population dynamics of Coregonus albula, a small, schooling salmonid fish. Using an empirically-based eco-evolutionary model, we investigated how the presence or absence of senescence affects how the fish population responds to pristine, intensive harvest, and recovery phases. Our results showed that at an individual level, the presence of senescence was accompanied by life-history trade-offs, i.e. lower asymptotic length and smaller size and younger age at maturity, both in the presence and absence of fishing. At the population level, the response to different fisheries selection patterns depended on the presence or absence of senescence. Importantly, the results indicate that through the lifehistory trade-offs between early reproduction and late life survival, the young and small individuals can have an important role in population recovery, especially when senescence is present. Since most life-history and fisheries models ignore senescence, they may be over-estimating reproductive capacity and under-estimating natural mortality. Our results highlight the need for increasing biological realism in these models to ensure the successful management of our natural resources.