provides a topical forum for the coordination (i.e. those species which use
both freshwater and marine environments to complete their life cycles), like
eel, Atlantic salmon, sea trout, lampreys, shads, smelts etc. The Group
considers progress and future requirements in the field, organizes other Expert
Groups, Theme Sessions and Symposia, and helps to deliver the ICES Science Plan.
There is a significant role in co-ordinating with other science and advise
working groups, science steering groups under SCICOM and also ACOM.
species face a number of common problems. Destruction of freshwater and coastal
habitats has decreased survival and productivity of diadromous fish
populations. Migration obstacles, water abstractions and other activities are
reducing the freshwater habitat available for the species. Various human
interests to utilize both freshwater and marine environments are in conflict
with the well-being of these species. Moreover, several diadromous species are
highly valued commercially and it is a major challenge to keep exploitation of
these species at sustainable level. The species do not usually have a
significant quantitative role in a marine ecosystem, but they are one of the
few concrete linkages between freshwater and marine ecosystem and serve as
indicators of the status and the functionality of both ecosystems. A persistent
decline in marine survival has been common to several of these species
resulting in a need for international collaboration and advice.
research on diadromous species ranges from developing specific assessment
methodologies suitable for the life histories and migratory behaviour to
addressing research questions related to the well-being of the species. The human dimension is often strongly present e.g. conflicts between energy production using
hydropower/wind power and wave energy vs. preserving and restoring habitats and
their connectivity for the species. ICES’s role as a promoter of the international
coordination in these research fields is central.
many of the diadromous species are protected under international laws or
conventions (IUCN, Habitats Directive, Species at Risk Act, USA) and
increasingly more information is being sought on the status of these species
and activities which cause difficulties for survival and sustainability.
Copyright: Pekka Tuuri, Finland