Systematic review of somatic growth patterns in relation to population structure for Pacific Sardine (Sardinops sagax) along the Pacific Coast of North America

Management of the Pacific Sardine (Sardinops sagax) in the U.S. recognizes two biological subpopulations along the Pacific coast of North America based on the hypothesis formalized by Marr (1960), with presumed heritable differences in somatic growth patterns used as supporting evidence. Consistent with this hypothesis, length-at-age data and growth information are used as corroborative evidence for a habitat model that apportions Pacific Sardine sampled from scientific surveys and commercial catches to each subpopulation for use in annual stock assessments. We completed a systematic review of published scientific studies that examined somatic growth in Pacific Sardine along the Pacific coast, with an emphasis on those focused on population structure. We summarized the methods, results, and conclusions of each study and the prevailing hypothesis linking growth to population structure. We then evaluated the evidence in support of heritable growth patterns versus alternative explanations based on the quality of each study in light of best practices.