Evaluating drivers of spatial variability in lingcod, Ophiodon elongatus, reproduction along the US West Coast

Abstract

Examining variation in reproduction (estimates of maturity and adult skip spawning) over time and space provides vital information on stock structure for managing coast-wide species; however, it is equally important to identify the drivers of variability, i.e., fishing pressure, genetics, and oceanographic conditions. The 2021 lingcod, Ophiodon elongatus, stock assessments used separate population models, north and south of 40°10′ N, based on evidence of distinct population clusters and historical fishery trends. We collected 1035 lingcod ovaries along the US West Coast over seven years (2013–2019) to evaluate trends in reproduction and inform stock management decisions. We estimated biological (physiological maturity) and functional (potential spawners) length (L₅₀) and age (A₅₀) at 50% maturity across eight regions: coast-wide, between management areas (north and south of 40°10′ N), genetic stocks (north and south of 38°17′ N), and among important biogeographic regions including Cape Mendocino, California (north of 40°10′ N), the Central coast (40°10′–34°26′ N), and Pt. Conception, California (south of 34°26′ N). Regional biological L₅₀ and A₅₀ maturity estimates (43.36–52.75 cm and 1.66–2.88 years) were smaller than functional maturity (46.31–56.65 cm and 1.89–3.23 years). Overall, regional analyses showed a decline in size and age at 50% maturity with decreasing latitude, with females south of Pt. Conception reaching maturity at much smaller sizes and younger ages than their northern counterparts. These regional estimates of maturity add to the growing body of literature that seeks to determine the best spatial management plan for lingcod sub-populations.