Abstract

While movements of organisms have been studied across a myriad of environments, information is often lacking regarding spatio-seasonal patterning in complex temperate coastal systems. Highly mobile fish form an integral part of marine food webs providing linkages within and among habitats, between patches of habitats, and at different life stages. We investigated how movement, activity, and connectivity patterns of Atlantic cod (Gadus morhua) are influenced by dynamic environmental conditions. Movement patterns of 39 juvenile and subadult Atlantic cod were assessed in two coastal sites in the Swedish Skagerrak for 5 months. We used passive acoustic telemetry and network analysis to assess seasonal and spatial movement patterns of cod and their relationships to different environmental factors, using statistical correlations, analysis of recurrent spatial motifs, and generalized linear mixed models. Temperature, in combination with physical barriers, precludes significant connectivity (complex motifs) within the system. Sea surface temperature had a strong influence on connectivity (node strength, degree, and motif frequency), where changes from warmer summer waters to colder winter waters significantly reduced movement activity of fish. As the seasons changed, movement of fish gradually decreased from large-scale (km) linkages in the summer to more localized movement patterns in the winter (limited to 100s m). Certain localized areas, however, were identified as important for connectivity throughout the whole study period, likely due to these multiple-habitat areas fulfilling functions required for foraging and shelter. This study provides new knowledge regarding inshore movement dynamics of juvenile and subadult Atlantic cod that use complex, coastal fjord systems. The findings show that connectivity, seasonal patterns in particular, should be carefully considered when selecting conservation areas to promote marine stewardship.

Keywords

acoustic telemetry; coastal seascape ecology; fish movement; network analysis; seagrass habitat

Published in

Ecology and Evolution
2019, Volume: 9, number: 16, pages: 9076-9086
Publisher: WILEY

SLU Authors

• Hammar Perry, Diana

  • Department of Aquatic Resources (SLU Aqua), Swedish University of Agricultural Sciences
    
  • Stockholm University

UKÄ Subject classification

Fish and Aquacultural Science


Publication identifier

DOI: https://doi.org/10.1002/ece3.5453

Permanent link to this page (URI)

https://res.slu.se/id/publ/101186