North Atlantic Salmon Conservation Organization | est 1984

NASCO Rivers Database

The NASCO Rivers Database

Welcome to the NASCO Rivers Database.

Atlantic salmon occur in rivers from Spain and Portugal in the south to Arctic Russia in the north, on the eastern side of the Atlantic, and from New England, USA in the south to Ungava Bay in the north on the western side. Conditions in these rivers vary markedly as does the status of the salmon stocks they contain.

In the Rivers Database you can view salmon rivers on the interactive map including their stock status. The data included were provided by Parties / jurisdictions between late 2017 and early 2019. A total of 2,359 rivers are reported on. The three tables below explain the data provided. Not all Parties were able to populate all fields for all rivers.  

  • Table 1. The fields displayed and a description of the data in each field;
  • Table 2. The stock classification system used by each Party; and
  • Table 3. The stock classification score.

Table 1. The fields displayed and a description of the data in each field

Field Name Description
River A river is named as the main stem of the system of rivers and tributaries where it reaches the sea
Salmon Stock Category Status of the salmon stock relative to conservation limits, or, where these have not been established, other reference points or indicators of abundance
Country Country
Region / Province Region or province
Latitude 2 digits of degrees plus 2 digits of minutes, zero-padded where required e.g. 0464, not 464
Longitude 2 digits of degrees plus 2 digits of minutes, zero-padded where required
Catchment Area Square kilometres (km2)
Total River Length Kilometres (km)
Axial River Length Kilometres (km)
Accessible River Length Kilometres (km)
Mean Annual Flow Cumecs (m3s-1)
Main Impact Factors A description of the main factors adversely affecting the salmon stock
Total Conservation Requirement Total number of salmon
1SW Conservation Requirement Number of 1 sea-winter salmon
MSW Conservation Requirement Number of multi-sea-winter salmon
Special Stock Characteristics For example, run timing
Other Information For example, details of any designations; protected areas

Stock Classification

Many rivers are classified using the Stock Classification Score developed by the Working Group on Stock Classification, CNL(16)11. However, some Parties / jurisdictions used alternative approaches. The data included were provided by Parties / jurisdictions between late 2017 and early 2019. Details are provided in Table 2. 

Table 2. The stock classification system used by each Party

Party / jurisdiction Stock Classification used
Canada A ‘read across’ from national river assessments
Denmark (in respect of the Faroe Islands and Greenland) Greenland Taken from the Implementation Plan
European Union (except Spain) 2016 Stock Classification Score
EU – Spain Taken from the Implementation Plan
Norway 2016 Stock Classification Score
Russian Federation 2016 Stock Classification Score
United Kingdom (except Scotland) 2016 Stock Classification Score
UK – Scotland UK – Scotland’s stock classification data have been generated by creating a simple read across from Scotland’s national gradings, which are defined by the probability of the stock meeting its conservation limit over a 5-year period. Further information is available here.
USA 2016 Stock Classification Score

The 2016 Stock Classification

For those rivers categorised using the 2016 Stock Classification Score, it is based on:

  • Conservation limits Attainment Score (CAS): based on available information concerning the extent to which the conservation limit is being attained; and
  • Impacts Assessment Score (IAS): based on a range of factors including: habitat degradation e.g. deterioration in water quality or obstacles to migration; over-harvest or selective harvest; diseases and parasites, e.g. sea lice; G. salaris; impacts on genetic integrity e.g. due to aquaculture escapees; or a steadily declining stock trend where the causes are unknown.

The CAS and IAS are added together to assign a Stock Classification Score to a river.

Table 3. The 2016 Stock Classification

Stock classification for Rivers Database 2016

Amalgamated data from the Rivers Database was used in the State of North Atlantic Salmon Report.

A history of the Rivers Database can be found in the Report of the Working Group on Stock Classification, CNL(16)11.