Ted Potter, Co-Chair of the Workshop of Sea Trout 2 (WKTRUTTA2)
'The term 'transitional waters' came into general use in 2000 with the publication of the EU Water Framework Directive and was designed to provide an ecologically relevant definition of the continuum between freshwaters and coastal marine waters. For the purposes of legislation they are defined as 'bodies of surface water in the vicinity of river mouths which are partially saline in character as a result of their proximity to coastal waters but which are substantially influenced by freshwater flows'.
These waters include a diverse range of ecosystems types, such as lagoons, fjords, brackish wetlands and river mouths, and are therefore important to a wide array of species that may reside in them or use them as, for example, spawning or nursery habitats. For sea trout and other diadromous (migrating between fresh and salt water) species such as salmon, eel, shads and lampreys, they are often thought of simply as migration pathways between freshwater and marine environments, but conditions in transitional waters may be critical for these species during this important stage in their lives.
Unfortunately transitional waters are under severe stress from anthropogenic pressures such as port activities, dredging, renewable energy schemes, and pollution from urban, industry, agriculture and aquaculture, and are considered to be among the most impacted and 'at risk' ecosystems. The behaviour, distribution and habitat utilization of many species in these areas is poorly understood making it difficult to safeguard them from the potential impacts of environmental modification as a result of infrastructure developments.'