Seasonal Movements of European Sea Bass in Local Waters

Jim Crocker
12th June, 2024

Seasonal Movements of European Sea Bass in Local Waters

Image Source: Natural Science News, 2024

Key Findings

  • The study tracked 171 mature European sea bass in the English Channel, southern North Sea, and Irish Sea using electronic tags
  • Sea bass showed distinct seasonal movements, staying in shallower areas during warmer months and moving to deeper spawning areas in colder months
  • Some sea bass remained in the North Sea year-round, suggesting possible spawning in this region, challenging previous assumptions
Understanding the movements and behaviors of mature European sea bass (Dicentrarchus labrax) in UK waters has been a long-standing challenge. The Centre for Environment, Fisheries and Aquaculture Science (Cefas) recently conducted a study to address this knowledge gap by tagging and tracking sea bass to gather detailed data on their seasonal migrations and habitat use[1]. In the study, 171 mature sea bass, each over 42 cm in length, were internally tagged with electronic devices that recorded temperature and depth. These fish were released in three distinct locations: the English Channel, the southern North Sea, and the Irish Sea. To date, 48 of these tags have been returned, providing valuable data on the movements and behaviors of these fish over an average of 370 days, with recoveries averaging 172 km from their release points. The majority of tags were recovered from beaches (54%) and via fisheries (44%). The data revealed that sea bass exhibit distinct seasonal movements. During the second and third quarters of the year, they were found in shallower areas, while in the fourth and first quarters, they moved to deeper spawning areas. This pattern was accompanied by changes in vertical swimming speeds and water temperatures, with average temperatures of 8.5°C in the English Channel and Irish Sea, and lower temperatures in the North Sea. These findings suggest a high level of connectivity between the Celtic Sea/Irish Sea and the North Sea, indicating that sea bass migrate extensively between these regions. Interestingly, the study also found that some sea bass remained resident within the North Sea throughout the year, with a strong indication that spawning might be occurring in this area. This discovery challenges previous assumptions and highlights the complexity of sea bass behavior and habitat use. The findings of this study have significant implications for the sustainable management of sea bass stocks in UK waters. By understanding the seasonal movements and habitat preferences of sea bass, fisheries managers can develop more effective conservation strategies to protect this valuable species. The use of electronic tags in this study builds on previous research that employed mark-recapture methods to study fish movements[2]. The combined use of both techniques provided a comprehensive view of sea bass behavior and habitat use. Additionally, the study's findings align with earlier research on the movement patterns of other marine species, such as the starry smooth-hound shark, which also exhibited seasonal changes in habitat use and geographical distribution[2]. Furthermore, the study's methodology of using electronic tags to collect high-resolution data on fish movements is similar to approaches used in other studies, such as the investigation of European sea bass depth time series through spectral analysis and hidden Markov models[3]. These advanced techniques allow researchers to extract and quantify complex behaviors from movement data, providing valuable insights into the underlying processes driving animal movements. In conclusion, the Cefas study on mature European sea bass in UK waters provides critical information on their seasonal migrations and habitat use. By leveraging electronic tagging technology, the researchers were able to uncover detailed patterns of sea bass behavior that have important implications for the sustainable management of this species. The study also highlights the value of combining different research methods to gain a comprehensive understanding of marine animal movements and behaviors.

EcologyAnimal ScienceMarine Biology

References

Main Study

1) Seasonal migrations of the European sea bass (Dicentrarchus labrax L.) in UK and surrounding waters

Published 11th June, 2024

https://doi.org/10.1186/s40462-024-00482-w

Related Studies

2) Horizontal and vertical movements of starry smooth-hound Mustelus asterias in the northeast Atlantic.

https://doi.org/10.1371/journal.pone.0239480

3) Coupling spectral analysis and hidden Markov models for the segmentation of behavioural patterns.

https://doi.org/10.1186/s40462-017-0111-3


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