Habitat restoration and protection effects on european lobsters (Homarus gammarus): the livø stone reef marine protected area, Limfjorden

The Limfjorden has a significant European lobster (Homarus gammarus) population since the mid- 2000’s, following 4 decades of being virtually absent, supporting the largest Danish lobster fishery currently at 45 tonnes and 7 Mio.kr. per year, with significant economic and cultural value to local coastal communities. The Livø stone reefs (LR) were established in 2016 to restore a rare, degraded habitat and associated ecosystem services. A small, protected area (MPA) surrounding the reefs and closed to fishing was created in 2018. The effects of the LR-MPA on lobsters by providing rare reef habitat as well as fishing protection, were evaluated in 2021. Higher abundance, larger sizes and increased reproductive potential were observed in the LR-MPA relative to fished areas, as well as indication of sex specific habitat and protection effects. Lobsters showed high-site fidelity, occasionally with significant movements between LR-MPA and adjacent non-MPA areas. A clear positive effect of LR-MPA on the lobster population was thus observed after only 3 years since its implementation, likely resulting from increased survival and growth but also immigration and retention of large lobsters.