The site comprises a 50 km stretch along the north-eastern side of Trondheimsfjord, the third largest fjord in Norway, from south of Levanger to north of Steinkjer. This is a network of 10-12 key wetlands, some of which would qualify as IBAs individually. The main habitats are extensive shallow subtidal areas, intertidal mudflats and the mouths of two large rivers, Verdalselva and Steinkjerelva, as well as those of several smaller ones. Land surrounding the fjord is mainly cultivated, but semi-natural meadows remain intact in a few places. The site includes `Gjørv, Borgenfjorden', an IBA that was listed individually (as site NO030) in the previous European IBA inventory (Grimmett and Jones 1989).
Most or all of the Svalbard population of Anser brachyrhynchus (30,000 birds) probably stages in the area in May during spring migration, thus this is probably one of the most important stop-over sites in Norway for the species (c.3,000 stage at Gjørv [Borgenfjorden] alone). The geese forage on the mudflats, but spend the nights on the water. The area is notable as a staging area for other seabirds, waders and ducks as well. Seaduck such as Melanitta nigra, M. fusca, Bucephala clangula and Clangula hyemalis occur in large numbers on spring migration. The estimated number of geese, ducks, waders and gulls staging in the whole area is 35,000-60,000.
Pressure/threats to key biodiversity
Land-claim for industrial development, a horse-racing track and agriculture have destroyed some mudflats in the past. Aquaculture and military activities affect one site each. Local authorities have recently allowed a private land-owner to extract a total of 350,000 m³ of sand and gravel from the sea-bottom at Ørin. This will most probably result in habitat degradation for seaduck, especially for Melanitta nigra. Recreation and illegal hunting are also widespread problems. The County Governorate is carrying out a conservation plan for seabird areas (breeding, migrating/moulting and wintering seabirds). In addition to the four areas that are protected already, a further eight areas of mudflat and shallow sea will be protected within a few years. In addition, several islets important for breeding birds will probably be protected by law. There are annual counts of wintering seabirds, as a part of the `National Monitoring Programme for Seabirds', in the Trondheimsfjord. At two sites there are weekly bird counts between April and October, as part of other projects conducted by NOF.
National Low International None40 ha of IBA covered by Nature Reserve (Hammeren, 40 ha). 210 ha of IBA covered by Nature Reserve (Rinnleiret, 210 ha). 49 ha of IBA covered by Nature Reserve (Ørin, 49 ha). 230 ha of IBA covered by Flora and Fauna Protection Area (Eidsbotn, 230 ha).