Mussel populations (Mytilus edulis) around the coasts of Europe and the North Atlantic are often ephemeral and have notably experienced a large decline in abundance. Identifying factors that govern the fluctuation and longevity of mussel populations is important for the management of the fishery, setting conservation targets, and coastal restoration purposes. Since 1993, annual blue mussel stock surveys have been carried out in the Limfjorden, Denmark. We used the stock survey data combined with electronic monitoring fishing data and a Mechanistic Model for Limfjorden, providing environmental data, to investigate the longevity of subtidal mussel beds. Multiple factors were found to affect the longevity of subtidal mussel beds in Limfjorden. Our study reveals that predation by starfish, fishing activities, and consecutive days of oxygen depletion are significant factors, negatively impacting bed stability. Conversely, increased biomass and the presence of multiple cohorts demonstrate stabilizing effects on mussel beds. These analyses can help inform environmental, conservation, and fisheries managers on the long-term trends of population dynamics and factors contributing to the variability in population stability in the context of declining stocks.

Primary Presenter: Isabelle Johansson, Denmark technical university (DTU aqua) (isjoh@aqua.dtu.dk)

Authors:

Isabelle Johansson, Technical University of Denmark  (isjoh@aqua.dtu.dk)

Camille Saurel, Technical University of Denmark  (csau@aqua.dtu.dk)

Daniel Taylor, Technical University of Denmark  (dtay@aqua.dtu.dk)

Jens Petersen, Technical University of Denmark  (jekjp@aqua.dtu.dk)

Pernille Nielsen, Technical University of Denmark  (peniel@aqua.dtu.dk)