Decade-scale spatio-temporal variability in maturity of Pacific hake, Merluccius productus, along the US West Coast Environmental Biology of Fishes

Pacific hake, Merluccius productus, is the most abundant groundfish in the California Current Large Marine Ecosystem and plays a vital role in predator–prey dynamics. Hake population dynamics are driven by large annual fluctuations in recruitment and intense levels of harvest. The sustainability of harvests relies on stock assessment models reflecting accurate population trends and life-history parameters, such as the size or age at maturity and the rate at which mature adults fail to spawn. We evaluated biological and functional maturity of Pacific hake from 2009 to 2021 using histological samples collected along the West Coast of North America. Maturity parameters were estimated using a standard asymptotic logistic curve and a more flexible cubic spline to evaluate reductions in functional maturity at older ages. We uncovered temporal variability in maturity across years (length and age at 50% functional maturity ranging from 29.89 to 37.89 cm and 1.93 to 3.24 years). There were also significant increases in functional maturity for fish north of Pt. Conception, CA (nearly 9 cm larger and 1 year older). Pacific hake were found to spawn batches throughout the year and along the entire US West Coast, extending previous reports of spawning occurring primarily in southern California from January to February. To support sustainable fisheries management, biological collections should provide data that allow for consideration of non-stationary life history parameters in stock assessments, such as spatio-temporal differences in maturity.