Diadromous species use freshwater environment for reproduction and marine as a feeding area or vice versa. While some diadromous fish species (e.g. salmonids, eel) are famous around the globe and highly valued, others attract far less attention from policy-makers, scientists, or stakeholders but are likely to make crucial contributions to complex marine, transitional, and freshwater ecosystems.
Many diadromous fish species have threatened status and suffer from environmental degradation and human-induced changes, especially in reproduction areas. The main threats to diadromous fish include migration barriers (e.g. dams), river construction, local inputs to rivers, lagoons, and estuaries (pollution, eutrophication, acidification), habitat loss, and overfishing.
The latest publication in ICES Cooperative Research Reports series, CRR No.348 Data-limited diadromous
species – review of
European status, updates the status and distribution of selected species that have completely or partially diadromous populations.
The report has been researched by the Working Group on Data-Limited Diadromous Species (WGDAM), a subgroup of ICES Working Group on the Science Requirements to Support Conservation, Restoration and Management of Diadromous Species (WGDIAD).
The group has identified biological knowledge gaps and key stressors of diadromous species and the report delivers fundamental information for further work on development of systematic monitoring and stock assessment of key diadromous species or species groups.
Editors Lari Veneranta, LUKE, and Karen Wilson, University of Southern Maine, say the report provides a good review package of information on data-poor diadromous fish, mainly in Europe. "Maybe these species will be a bit less data-poor now for stakeholders, for example environmental and fisheries authorities" states Veneranta.
Diadromous fish are also in focus at ICES Annual Science Conference 2019 which takes place in Gothenburg next week. Theme session N looks at Advances in data-limited assessment methodologies for marine and diadromous stocks.
One week old anadromous whitefish (Coregonus lavaretus) from River Perho in western Finland.