Assessing the role of ontogenetic movement in maintaining population structure in fish using otolith microchemistry. Issue 16 (16th July 2018)

• Record Type: Journal Article
• Authors: Wright, Peter J.; Régnier, Thomas; Gibb, Fiona M.; Augley, Julian; Devalla, Sandhya
• Is Part Of: Ecology and evolution. Volume 8:Issue 16(2018)
• Page Start: 7907
• Page End: 7920
• Publication Date: 2018-07-16
• Subjects: Atlantic cod -- marine fish -- natal homing -- otolith chemistry -- philopatry -- population structure; Ecology -- Periodicals; Evolution -- Periodicals; 577.05
• DOI: 10.1002/ece3.4186
• Languages: English
• ISSNs: 2045-7758

Abstract

Abstract: Identifying the mechanisms maintaining population structure in marine fish species with more than a single dispersing life stage is challenging because of the difficulty in tracking all life stages. Here, a two‐stage otolith microchemistry approach to examining life‐stage movement was adopted, tracking a year‐class from the juvenile to adult stage and inferring larval sources from clustering, in order to consider the mechanisms maintaining population structuring in North Sea cod. Clustering of near‐core chemistry identified four clusters, two of which had either a southern or northern affinity and were similar to juvenile edge chemistry. The other two clusters, common to the central North Sea, had intermediate chemical composition and may have reflected either larval mixing in this region or a lack of geographic heterogeneity in the elemental signature. From the comparison of whole juvenile and the corresponding component of adult otoliths, adults from the southern North Sea mostly recruited from adjacent nursery grounds. In contrast, many adults in the northern North Sea had a juvenile chemistry consistent with the Skagerrak and juveniles from the northern Skagerrak site had a near‐core chemistry consistent with the northern North Sea. Similarities in otolith chemistry were consistent with retention of early life stages at a regional level and also juvenile and adult fidelity. The links between the northern North Sea and Skagerrak indicate natal homing, which when considered in the context of genetic evidence is suggestive of philopatry. The approach used here should be useful in exploring the mechanisms underlying population structuring in other species with multiple dispersive life stages and calcified hard parts. Abstract : This study used a two‐stage otolith microchemistry approach to examine life‐stage connectivity within populations of North Sea cod. Analyses of otolith chemistry were generally consistent with retention of early life stages in the shallow southern and deep northern North Sea, together with juvenile and adult fidelity. However, there was also evidence of natal homing from juveniles that had moved into the Skagerrak.