Meeting in late June in Italy, WGVHES' main goal was to build the foundation to contribute aspects of coastal habitats quantitatively into models of population dynamics on the exploited species on two fronts – for those which ICES delivers advice on and for those that have key roles in the foodwebs of ICES species.
Twelve participants from seven counties made up the latest group get-together, which comprised scientists operating in the fields of modelling, marine ecology, fisheries management and conservation biology. Collectively they evaluated the overall importance of coastal habitats – a diverse group of natural features from shallow seawater to beaches, rock pools, and rocky shores and coves – as well as assessed the ecological functions that these provide. Such functions include nursery grounds for juvenile fish and shellfish like seagrass and kelp beds, salt marshes and rocky sea bottoms as well as feeding grounds, spawning areas, and those areas that play a part in migration.
Håkan Wennhage, who co-chairs WGVHES along with Rom Lipcius, explained:
"Shallow coastal habitats are generally believed to be important nursery grounds providing refuge from predation and scope for growth in terms of food supply and physical conditions. Many of the commercial stocks fished off-shore are found in coastal habitat during their early life-stages, but how fish stocks are affected by changes in coastal habitat quality and quantity are largely unknown."
Through its work, the group found that 44% of all ICES species utilize coastal habitats in some way, with the relevant stocks contributing 77% of all commercial landings of species for which the organization delivers advice. These statistics confirmed the significance of coastal habitats for both a self-sustaining population and potentially for fishery yields of ICES species. Overall the results show the need for more knowledge on the habitat dependence of commercially exploited species from life stage to population and ecosystem level.
"Behind these statistics are some good examples where habitat dependence has been shown, but many more where habitat dependence has been inferred rather than tested," continued Wennhage. "The review of coastal habitat use in commercial species highlighted the need for sampling, mechanistic understanding, and modelling of how habitat change affects demographic rates in fish and shellfish populations."
The group now wants to progress into further quantifying coastal habitats and management use of them. Knowledge of fish's reliance on such environments can be modelled and developed to inform spatial management decisions such as those built around Marine Protected Areas (MPAs) and the Marine Strategy Framework Directive (MSFD) as well as helping stock recovery and bycatch reduction.
According to Wennhage, factoring the habitats studied by his group in to a larger ecosystem context will be crucial in future efforts.
"Habitat dependence in commercial fish species will need to be a research priority with physical planning of the sea becoming increasingly important and with threaths to coastal habitats remaining a critical issue. We will continue to work on impacts of habitat changes on ecosystem structure and function and their role in causing recruitment and stock variability, depletion and recovery," he added.
On top of that, WGVHES efforts may aid understanding in ecosystem-level approaches, with the value of the shoreline habitats for exploited species being highly relevant to the ICES science plan given its focus on integrated ecosystem assessments and advice for ecosystem based management.
During a field trip to the Marine Protected Area off the island of Ustica to the west of Italy’s southern tip, a turtle, an animal highly dependent on coastal habitats, was found entangled in the remains of a fishing net. Showing their dedication to the cause, the turtle was retrieved from the sea floor and brought back to the boat by WGVHES members Elliot and Olivier. Later it was safely released back into the sea.