Salmon stocks threatened by decline in fry numbers
Some salmon stocks in Wales are facing an ‘unprecedented’ threat after a dramatic decrease in the numbers of salmon fry in several Welsh rivers.
Routine monitoring by Natural Resources Wales (NRW) officers revealed fry numbers (young salmon hatched in the spring of 2016) at critically low levels on the Usk, Tywi and Clwyd in most of the sites fished. These are rivers which previously produced consistent fry numbers.
In the Tywi catchment fisheries surveys this year found salmon to be absent from 31 of the 37 sites monitored and of the 13 survey sites on the Usk, eight had no salmon fry at all and the remaining five had very low numbers, while not only have no salmon fry been recorded on the Clwyd but the catchment is also seeing its worse trout fry numbers on record.
Thankfully, surveys on the Tawe, Glaslyn and Wye are at normal levels.
Peter Gough, NRW Principal Fisheries Advisor, said:
“These initial survey results are unprecedented in Wales in 30 years of monitoring and are clearly very concerning, especially as our salmon and sea trout stocks already face serious challenges.
“The decline in fry numbers will not only harm the biodiversity of our rivers but could also have an economic impact on the angling and tourism sector.
”It is therefore imperative that we continue our investigations to discover the cause of the decline and put in place actions to ensure the maximum number of fish are able to spawn this winter and in future.”
Each year NRW monitors the juvenile fish stocks across Wales. This monitoring has an important role to play in the sustainable management of natural resources to help us understand, enhance and manage our fish stocks. Fish population surveys are carried out predominately using electric fishing to record the number of fish caught, the species and individual lengths.
At the moment the cause of the decline remains a mystery but possible reasons include extremes of river flow over the winter and high water temperatures in the affected rivers. The possibility of disease or parasites is also being considered but is thought most unlikely.
NRW’s fisheries team is stepping up its monitoring programme as part of its investigations into the cause of the decline, carrying out fish health checks and is consulting with the Centre for Environment, Fisheries and Aquaculture Science (Cefas) and the Environment Agency to establish whether there are similar problems in England.
“At the moment we are trying to establish the level of threat to Welsh salmon stocks and we will be working with the angling community to protect our existing stocks.
“We are working closely with our partners and sponsoring Government departments to investigate the causes. It is too early to be sure on the cause or causes, however we note that December 2015 was the warmest and wettest December since records began.”
Dr Stephen Marsh-Smith, Chief Executive of Afonydd Cymru, (the association of rivers trusts in Wales) added:
“It’s important to understand that this finding by NRW will not immediately impact on returning salmon and sea trout numbers but will be evident in two to four years’ time.
” It is crucial that NRW, the Rivers Trusts and Welsh Government get together to press forward a recovery programme for this valuable resource as well as a full investigation into the cause and effects.”
“In the meantime, it is vital that every salmon and sea trout is left to spawn this year and of course in the coming years. We are therefore appealing to anglers to build on their excellent response to earlier appeals, and ensure that they release all of their fish as well as strongly encouraging others to do the same.”