Project: MARHAB – The Marine Habitats Project

Six European research institutions will join forces to find answers on how to improve the status of our marine habitats. They will adopt an ecosystem perspective, with focus areas like Skagerrak and Kattegat.

Although the EU Habitats Directive was agreed upon 30 years ago, several marine habitats and species still don’t meet the Directive’s objective of favorable conservation status. The situation is particularly pressing in Northern Europe, where the conservation status of marine habitats in the Kattegat-Skagerrak region is consistently poor.

“The state of marine habitats in Europe and elsewhere is tightly linked to fisheries, both via the direct physical impact of fishing – for example caused by bottom trawling, but importantly also via indirect effects of fishing” – says Even Moland, a researcher at the Norwegian Institute of Marine Research (IMR) and leader of the project.

Greater focus on the lack of large predatory fish

Particularly, the loss of large predatory fish and their regulating role causes so-called “trophic cascades”; where the loss of predatory fish disrupts the functioning of the ecosystem and leads to a deterioration of habitats. Studies have shown that the disappearance of predatory fish has similar effects as eutrophication.

While nutrient enrichment and oxygen depletion has received much scientific attention – and been a central focus for management efforts over several decades, the lack of large predators in coastal marine ecosystems has not received the same focus. 

“Marine protected areas (MPAs) are effective tools for biodiversity conservation – they provide protection to habitat, the animals that live there, and their interactions. Fisheries management has tools designed to ensure sustainability in fisheries, but maintenance of trophic dynamics should also be considered in future fisheries management” – says Moland.

To succeed in obtaining healthier marine ecosystems, we must promote broad size and age structure of harvested species - large and old individuals must also be protected. Functionally important species must be allowed to thrive and perform their essential roles in the ecosystem, regardless of management regime.