ICES and NASCO require countries with natural stocks of Atlantic salmon to set criteria against which to give advice on stock status and to manage and conserve individual river stocks. In England and Wales, conservation limits (CLs) have been developed to indicate the minimum spawning stock levels below which stocks should not be allowed to fall. In the South West region there are 20 rivers selected as main salmon rivers representing 2299ha of accessible wetted area for salmon. These rivers range in size and characteristics throughout the region.
All 20 main salmon rivers in the South West have salmon action plans (SAP). These contain an agreed list of actions that the Environment Agency, in partnership with outside interests who support the plan, are committed to address in order to meet locally the objectives of its sea trout and salmon strategy “better sea trout and salmon fisheries” launched in 2008.
7 of these rivers are also designated as special area of conservation (SAC) under the EU Habitats Directive (92/43/EEC) on Conservation of Natural Habitat and of Wild Fauna and Flora with salmon being the “qualifying species”. This stipulates that member states maintain or restore habitats and species to favourable conservation status and maintain additional protection measures.
Map of salmon rivers in the South West
Salmon populations have declined in most rivers in the region, however this varies in each river catchment and with the weather patterns each year. There was a slight improvement in numbers of returning fish and spawners in 2000 and 2001 and again in 2004, but the general trend has been downward since the late 1980s and the numbers in 2009 are estimated to be the lowest in the time series.
There is concern about environmental degradation in rivers, mainly in rural areas, caused by changing land use practices, especially agriculture and forestry. Issues of particular concern are siltation resulting from soil and bank erosion, pesticides from sheep dip chemicals, acidification and changes in river flows. The relative importance of these effects vary around the country and in each river catchment. The extent and nature of soil erosion impacts are being investigated and national water abstraction licence legislation is under review.
Changes in the British climate are predicted to become more pronounced and the most likely scenarios are for higher temperatures, wetter winters, drier summers and more extreme events of flooding and drought. In the future we are likely to need to introduce measures to reduce river temperatures as much as possible, especially on the chalk streams but also on the rain-fed rivers of Devon & Cornwall. Changes in climate are global and the increased natural mortality of salmon at sea in recent years may also be linked to climate change.
Conservation limits and management targets form only one part of the assessment of the status of a stock. Management decisions are never based simply on a compliance result alone. Because stocks are naturally variable, the fact that a stock is currently exceeding its CL does not mean that there will be no need for any management action. Similarly, the fact that a stock may fall below its CL for a small proportion of the time may not mean there is a problem. Thus, a range of other factors are taken into account. These include the structure of the stock and any evidence concerning the status of particular stock components, such as tributary populations or age groups. It is based on patterns of run-timing and the production of juveniles in the river sub-catchments.
Hampshire Avon and Dorset rivers
The Frome has been consistently around or above its CL for a number of years but its compliance probably not at risk, even though in 2003 & 2005 it recorded slightly below 100%. In 2014 its compliance is also predicted to be probably not at risk. The Hampshire Avon, Stour and Piddle all failed their CLs compliance and all of them are “at risk” in 2014.
Proportion of conservation limit attained from 1998 to 2009 in Hampshire Avon and Dorset salmon rivers
East Devon rivers
The River Exe has been above 100% since 1998 but its compliance is listed as uncertain because it is categorised 'probably not at risk' in the management objective. The Teign has recorded above 100% in the past 4 years except 2009. In 2009, current compliance on the Teign is “probably at risk”, however both the Exe and Teign are predicted to be “probably not at risk” in 2014. The Axe failed it compliance in 2007 and is currently “at risk” and predicted to be “probably at risk” in 2014.
Proportion of conservation limit attained from 1998 to 2009 in East Devon salmon rivers
South Devon rivers
The River Avon in Devon passed its compliance for a number of years, however 2009 did not achieve it. In 2009, current compliance is “probably not at risk”, and is predicted to maintain that in 2014. The Dart, Erme and Yealm have all recorded above 100% in the past but have all failed in 2009, and are currently “at risk”. In 2014 all are predicted to be “probably at risk”.
Proportion of conservation limit attained from 1998 to 2009 in South Devon salmon rivers
Tamar, Lynher, Tavy and Plym rivers
The Tamar has the highest CL limit set in the South West. In 2007 and 2008 it recorded below 100% compliance. In 2009 it is designated as “probably at risk”. The prediction of compliance in 2014 for the Tamar is to remain “probably at risk”. The Lynher compliance has been 6 years of passing 100%. It is currently in 2009, and predicted in 2014 to be, and remain at “probably not at risk”. The Plym and Tavy both failed the 2009 compliance. The Plym in 2009 is “at risk”. Due to the not passing its compliance level in the past 9 years, it is predicted to remain “at risk” in 2014. The Tavy passed in 2008, and failed in 2009. It is noted in 2009 as “probably at risk”, and looks to remain as this in 2014 predictions.
Proportion of conservation limit attained from 1998 to 2009 in the Tamar, Lynher, Tavy and Plym salmon rivers
Fowey and Camel rivers
The Fowey and the Camel both 'pass' the 2009 compliance and both consistently record over 100% since the scheme started. Current and predicted compliance in 2014 is “not at risk” for both rivers.
Proportion of conservation limit attained from 1998 to 2009 in the Fowey and Camel salmon rivers
North Devon rivers
The Taw has only recorded below the 100% CL twice since 1998, in 2001 and 2005 respectively which has caused its compliance to be listed as “probably not at risk”. It is predicted to be “probably not at risk” still in 2014. The Torridge and Lyn both failed in 2009 to reach compliance limits. They are both designated at “probably at risk” in both 2009, and predicted to remain there in 2014.
For further explanation please refer to Annex 2 in the Annual Assessment of Salmon Stocks and Fisheries in England and Wales 2007.
Proportion of conservation limit attained from 1998 to 2009 in North Devon salmon rivers
Compliance with management objectives
Compliance is based on the probability of the river meeting the management objective. It can be basically explained that the stock should be meeting or exceeding its CL in at least four years out of five. Status of the main salmon river catchments against their management objectives in 2009.
In the South West compliance with the management objective in 2009 was:
- 2 rivers (10%) were classified as ‘not at risk’ – i.e. had a high probability (> 95%) of meeting the management objective
- 5 rivers (25%) were classified as ‘probably not at risk’ – i.e. had a probability of between 50% and 95% of meeting the management objective
- 5 rivers (25%) were classified as ‘probably at risk’ – i.e. had a probability of between 5% and 50% of meeting the management objective
- 8 rivers (40%) were classified as ‘at risk’ – i.e. had a very low probability (<5%) of meeting the management objective.
In England and Wales compliance with the management objective in 2009 was:
7 rivers (11%) were classified as ‘not at risk’ – i.e. had a high probability (> 95%) of meeting the management objective
18 rivers (28%) were classified as ‘probably not at risk’ – i.e. had a probability of between 50% and 95% of meeting the management objective
17 rivers (27%) were classified as ‘probably at risk’ – i.e. had a probability of between 5% and 50% of meeting the management objective
22 rivers (34%) were classified as ‘at risk’ – i.e. had a very low probability (<5%) of meeting the management objective
Status of the main salmon river catchments against their management objectives in 2007