Catching nearly 9,000 wild Atlantic salmon parr might sound like a fisherman’s dream come true. But catching this number of young fish on the River Frome in Dorset this autumn is no dream, it is part of a unique research project being run by scientists from the Game & Wildlife Conservation Trust (GWCT) who have spent the past 40 years helping to unravel the mystery surrounding the dramatic 70 per cent decline of this iconic fish.
Each of these thousands of small Atlantic salmon parr that are caught in this research project is individually tagged with tiny chips known as Passive Integrated Transponders (PIT tags). These electronic tags enable the fish to be monitored by specially adapted tag detection equipment straggling the river in order to follow each individual fish through its complete life-cycle from leaving the river in spring for the sea to when they return to the river as adults in one to four years’ time when they are ready to spawn.
However, this year, the GWCT researchers found it hard to capture a sufficient number of young salmon to tag. The GWCT’s project team have been electronically tagging and monitoring fish in the river since 2005 and most years they anticipate catching more than 10,000 young fish as part of the long-term monitoring programme.
Dr Rasmus Lauridsen, who leads the GWCT’s salmon research on the river Frome, explains, “We had a very poor run of grilse (salmon that has spent one year at sea) in 2013, because of a very poor smolt run in 2012. The difficulty in capturing young salmon is likely a result of the low number of returning adults in 2013 resulting in less young salmon in 2014. However a number of other factors like the unprecedented long-term high water levels last winter might have had an impact by affecting egg and parr survival.”
This long-standing research is already identifying some surprising results on salmon migration strategies, which will help to inform future management of our rivers for the benefit of salmon populations and importantly their potential survival at sea.
Dr Lauridsen explains, “We noticed a substantial number of young salmon parr starting to migrate down the river in the autumn. Normally, this migration takes place in the spring when the salmon parr have reached a threshold size after one to five years. At this stage, they will undergo a physiological transformation into smolts, which is when they are ready to migrate to sea. Although these very early autumn migrations of young salmon parr have been noticed on other rivers in Europe and North America, it was the scale of this migration on the River Frome that was surprising; averaging more than 30 per cent of the recorded down-stream tagged fish. The autumn migration appears to be triggered by increases in flow in October and November and occurs mainly at night.”
The scientists initially thought that this indicated that the young salmon were undertaking an early migration to sea, but tests revealed that these autumn migrating parr were unable to tolerate salt water and were unable to leave the river at this early stage in their development.
Dr Lauridsen explains the potential impact of this early migration, “It is evident that a significant proportion of the Frome salmon parr population inhabit the lower river during the winter, which might be the case on other rivers too. Discovering this early migration therefore has potentially important management implications, indicating that certain habitats in the lower reaches of rivers need increased protection to enhance the over-winter survival of salmon parr. This could have long term significance for their survival and performance at sea.”
To gain further insight on the dramatic plight of Atlantic salmon, the GWCT fisheries scientists on the River Frome are collaborating with French scientists from the National Institute for Agricultural Research (INRA) in Brittany*.
This cross-border project called Morfish (Monitoring for Migratory Fish) is funded by the EU Interreg IV4A Channel Area Programme* and will run until June 2015. The aim of Morfish is to ensure that data from the three rivers – rivers Frome in Dorset, the Oir in Normandy and the Scorff in Brittany are collected in a similar way to facilitate their combined analysis. This will help to better understand drivers underlying changes in populations of migratory fish, particularly Atlantic salmon.
The tagging project is carried out in patnership with Cefas (Centre for Environment, Fisheries & Aquaculture Science), who assisted the GWCT during tagging.
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Photocaption: Using a special technique called electro-fishing, scientists from the GWCT’s Salmon & Trout Research Centre on the river Frome caught and attached electronic tags to nearly 9,000 young salmon parr this autumn as part of a research programme that is investigating the 70 per cent decline of Atlantic salmon.
Notes to editors
The Game & Wildlife Conservation Trust’s Salmon & Trout Research Centre on the river Frome is directly involved in the international effort to research wild Atlantic salmon declines and their causes. The entire river catchment has been transformed into an impressive natural river laboratory. To date, this research facility, which comprises the most technically advanced scientific monitoring equipment of any river in the country has collected more than 40 years of data, which will have an important input in the future management of adult salmon. Approximately 10 per cent of the Frome salmon population is fitted with PIT tags and this technology in conjunction with the electronic adult counter and the smolt trapping makes the River Frome salmon population one of the most comprehensively studied in Europe.
The Game & Wildlife Conservation Trust (GWCT) – providing research-led conservation for a thriving countryside. The GWCT is an independent wildlife conservation charity which has carried out scientific research into Britain’s game and wildlife since the 1930s. We advise farmers and landowners on improving wildlife habitats and we lobby for agricultural and conservation policies based on science. We employ 22 post-doctoral scientists and 50 other research staff with expertise in areas such as birds, insects, mammals, farming, fish and statistics. We undertake our own research as well as projects funded by contract and grant-aid from Government and private bodies. The Trust is also responsible for a number of Government Biodiversity Action Plan species and is lead partner for grey partridge and joint lead partner for brown hare and black grouse. For Information, contact: Morag Walker – Head of Media, Telephone – direct-dial: 01425-651000. Mobile – 07736-124097 www.gwct.org.uk
The European Interreg IVA France (Channel) – England Programme 2007-2013 is the IV generation of the Interreg programme between France and England. Around the Channel, French and English cross-border territories share common challenges. Since 1990, the European Union has run the Interreg programme (strand A) which subsidises projects with cross-border partners willing to work together. Each border area thus becomes a forum for exchanges and orchestrated efforts between European neighbours. The programme has a total of 173.5 million euros in grant available through the European Regional Development Fund (ERDF)
The Institut National De La Recherche-Agronomique (INRA) INRA is the leading European agricultural research institute and one of the foremost institutes in the world for agriculture, food and the environment. It is also the second largest public research institute in France. Founded in 1946, the National Institute for Agricultural Research (INRA) is a public research institution under the joint authority of the Ministry of Higher Education and Research and the Ministry of Agriculture, Agrifood and Forests. The research conducted at INRA concerns agriculture, food, nutrition and food safety, environment and land management, with particular emphasis on sustainable development. Government authorities, the farming and industrial worlds, and associations of citizens or consumers all have a crucial role to play in orienting, monitoring and valorizing research. INRA has an active partnership policy with: the socio-economic world: private companies, agricultural organisations, local authorities, public authorities which call upon the expertise of INRA scientists on the national, European and international levels. INRA is ranked 2nd in the world and 1st in Europe for publications in the agricultural sciences, and plant and animal sciences. It maintains scientific partnerships with major scientific research institutes worldwide, universities, and agronomy and veterinary schools, and is committed to helping build the European Research Area. It develops a large number of collaborative projects and exchanges with the scientific community in numerous countries in Europe, America, Asia and Africa. Human resources: 1,800 researchers, 2,500 engineers, 4,000 technicians and administrative staff, nearly 2,000 PhD students and more than 1,800 foreign students and researchers and approximately 2,000 interns hosted each year in research units.Organisation: 13 scientific divisions, 18 regional research centres, 6 metaprogrammes. Budget: €881,61 million for 2013.Status: public scientific and technological establishment (EPST)