Spatial, temporal, and environmental influences on Atlantic cod Gadus morhua offshore recruitment signals in Newfoundland

Abstract

Numerous studies demonstrate the utility of information from coastal seine surveys for monitoring juveniles of Atlantic cod Gadus morhua, but few studies have linked such surveys to older ages within cohorts. We related juvenile (age-0 and -1) cod population components at a long-term monitoring site in Newfoundland to offshore pre-adult (age-3) cod recruitment at multiple spatial scales and explored some environmental and biological factors that affect juvenile-recruit relationships. Our models revealed significant relationships between juvenile and pre-adult abundance. The strength of these relationships varied with distance from nursery habitats and among fisheries management zones. Additionally, chlorophyll a concentration and body length during early life stages appeared to influence the strength of the relationship between juvenile and age-3 abundance. The potential to use juveniles as general indicators of future pre-adult abundance can aid in planning for low recruitment years and improve inferences about the response of cod population abundance to environmental changes. This study contributes to the growing body of knowledge demonstrating the utility of juvenile surveys in anticipating future year-class strength.