Missing Migratory Fish

7 Dec

Looking at the October 2019 Environment Agency fish pass numbers. There is undeniably serious cause for concern with regard to the number of migratory fish entering northern rivers. This not only applies to all North East and Yorkshire rivers but many Scottish rivers. Only a small number of rivers in the very far north of Scotland appear to have had a reasonable 2019 season.

The River Wear in particular has had a poor season. Over the last 10 years the number of migratory fish travelling through the two counters at Framwellgate Dam has averaged approximately 18,000 fish per annum. However over the last 5 years this has dropped to 16,000pa.

In 2018 the number counted totalled 8669 and this year the figure is unlikely to exceed 6,500 which will be an all time record low.

So just taking the last two years into account, the River Wear has lost approximately 19,000 migratory fish. Of course, with the very wet 2019 autumn some fish will have avoided the counters altogether, however 2018 was particularly dry so it seems very unlikely that a substantial number of the missing fish avoided the count.

The River Tyne to a certain extent has managed to maintain equilibrium over the last 10 years, but this year figures seem to be as equally alarming as the River Wear with only 275 being counted through Riding Mill in October. Projecting forward from the end of October it looks as if this years count will be close to 20,000 which will be the lowest figure since 2002.

One bright spot seems to be the River Coquet where anglers report a better year than past but of course any improvement from a historical low base seems a reason for hope. Unfortunately due to counter problems and consequential data shortages there is little opportunity to measure the improvement.

The River Till has also fished better, particularly for Sea-trout so it could be that both the Till and Coquet have benefited from the shortened T&J Net season. However, since the ‘ T net ‘ trial appears to have been a relative success, in taking Sea-trout but releasing Salmon, there is the imminent danger that the EA will revert to the traditional Sea-trout netting season of May until the end of August, putting further pressure on declining Sea -trout stocks. In which case all game anglers need to be on their guard and be proactive if the EA try to re-establish this programme.

So what’s behind this decline.? Well obviously no one knows, but everyone’s guessing.

Is it agricultural pesticides, run-off from commercial forestry, poor water quality, fish farming, netting and avian and inshore seal predation or is it a cyclical phenomenon?

Hopefully the ‘Missing Salmon Project will quickly tell us and enable swift action to be taken to counter the decline.

One interesting observation from the article ‘Missing Salmon’ posted below on 22nd of November 2019 refers to the loss of some 65% of smolts in one trial ‘ in river ‘ which will come as no surprise to anglers who watch our avian friends in action. Still better not to jump to hasty conclusions.

Missing Salmon?

22 Nov

From today’s Telegraph.

quest to solve one of Britain’s most haunting natural mysteries is to get underway next week when an alliance is launched to save the wild Atlantic salmon.

The fish, which famously overcome fearsome currents and obstacles to spawn in the rivers where they were born, have seen numbers collapse by 70 per cent in a quarter of a century.

But their extraordinary life cycle, which sees them spend the first years of life in fresh water before disappearing into the vast open ocean, has made tracing the cause of their decline all but impossible.

“We’ve got a pile of possibilities a foot high,” says Mark Bilsby, CEO of the Atlantic Salmon Trust (AST). “Is it obstacles to migration, water quality, predation? Then there’s climate change, which really does change everything, from food availability to water temperature.”

Warming waters around coastal Britain, for example, have seen species like bass, which predate on smolts (as adolescent salmon are known) migrate northwards towards traditional salmon waters off Scotland. “That’s one theory, but everyone has a theory, and we need to move away from pet issues. We need the science, the data.”

To compile that data, that AST has banded together with three other major campaigning organisations – the Angling Trust, Game and Wildlife Conservation Trust and Salmon and Trout Conservation – to launch The Missing Salmon Alliance.

The Alliance, which will be unveiled next Tuesday, will unveil a “Likely Suspects Framework”, listing possible culprits for the salmon population collapse. These include agricultural pesticides, run-off from commercial forestry, poor water quality, fish farming, netting and avian and inshore seal predation, among others.

The aim now is to collect data in order to eliminate those suspects from the Alliance’s enquiries, or select them for further questioning.

“You have to have the evidence,” says David Mayhew, a city grandee who was chairman of JP Morgan Cazenove until 2011, and has spent the last three years convening the Alliance. “Everyone who has ever held a rod has a theory. But it’s the science that matters. I believe it will transform our understanding of salmon which, as things stand, is on its way to extinction.

“That’s how serious the trend is.”

The data-rich, scientific modelling on which the Missing Salmon Project is based is a fruit of Mayhew’s experience as chairman of Alzheimer’s Research UK, where he helped ensure that academic work on drug discovery was translated as far as possible into practical action.

In an echo of that governing structure, researchers aiming to gather information which may identify the guilty party in the salmon’s decline will report to a steering committee at the Alliance which will coordinate a policy response.

“We had four separate salmon preservation bodies and many more internationally not working as one group,” says Mayhew, who himself fishes the Islamouth beat on the Tay near Perth. “Three years ago, I said it would be better for us and the fish if we banded together. Now we have, and in a meaningful way.”

The “Likely Suspects” framework is inspired in part by work done to help save stocks of cod in the Irish sea. “It’s about separating potential causes into bite-size chunks” says Bilsby. He notes that the complexity of factors affecting an animal which can roam from the White Sea off Arkhangelsk, northwest Russia, to the coast of Canada, and as far south as Spain, means it is always currently possible to point the finger of blame elsewhere.

Key to the project is pioneering work tracking salmon and identifying the threats they face on their journeys out into the Atlantic. This year the Atlantic Salmon Trust used acoustic tags to track 850 smolts as they swam out from the headwaters of seven rivers in the Moray Firth. The results were startling. “Two thirds were being lost before they really got out to sea, in the first 60 miles of their journey,” Bilsby says. “Now we know where they died. Next year we want to find out what caused that?”

For the fish, making it well out into the ocean is crucial. Many smolts are just 6in long when they leave, but those that do survive can be more than 4ft long when they return after two or three winters away.

The tracking project, which Bilsby describes as “by far Europe’s largest” was complemented by similar scheme run by the Game and Wildlife Conservation Trust, which followed salmon further south, as they moved out into  the Channel from rivers in England and France.

“The issue is more than local or national,” he says. “It’s a global problem. Even in the Pacific they’ve seen similar problems with their salmon.”

Campaigners around the world are particularly concerned because they see the salmon as a bellwether species which, almost uniquely, indicates the health of both freshwater and marine ecosystems.

“We had between eight and 10 million swimming around the Atlantic in the mid-1980s and between 2-3 million now,” says Bilsby. “That is a crisis. “The salmon is such a canary of the sea and the rivers. And the song it’s singing is that we now have a major problem.”

The plan to solve that is essentially three-fold, of which convening the Alliance is the first part. Identifying the cause of the decline is part two, and doing something about it is part three. All concerned acknowledge it will be a long game.

“There aren’t going to be quick wins,” says Mayhew. “It will outlive me.” But he insists that rapid recent strides in data collection and analysis techniques will eventually solve the mystery of the missing salmon. “It can be done with modern technology.”

He knows as well as anyone the effects of the salmon population collapse. “The autumn run this year was remarkably diminished,” he recalls. At first he describes the salmon numbers as “very disappointing”. Then he pauses and offers an even gloomier assessment. “It’s frightening really. It’s absolutely evident there’s something wrong. This is a lot to do with the environment, with mankind. It’s not that different to so many other species.”

Speedy Salmon?

6 Nov

Fish speeds and ability to leap.

Ever wondered why some fish seem to disappear so quickly when spooked, then here’s your answer. The following Environment Agency chart gives the swimming abilities of the species named.

Interestingly the world record swimming speed for a human was set in 1990 in Nashville Tennessee by Tom Jager of the USA who recorded a time of 2.29m/s (equivalent to 5mph) over 50 meters. So by direct comparison, humans in water can be quite quick, but a fish out of water – well they’ve got no chance!

Durham Hydro – Update.

20 Oct

During the current season (2019) the number of migratory fish trying to enter the Archimedes screw chamber seems to have declined. This is in no small part due to the operators Durham County Council, to there credit, turning the screw revolutions down during the period May till the end of October. This has reduced the white water at the base of the screw providing less of an attraction to migrating fish. Although during periods of high water fish have still been using the Larinier fish pass at the side of the screw.

There does not appear to have been any significant fish mortalities this season and it is believed that the operators have still been able to generate sufficient energy to meet their needs.

The protective flaps over the chamber also appear to have worked and it is anticipated that these will be lengthened in due course as a further preventative measure.

Along with these measures the Environment Agency have commissioned an independent report from a company specialising in the design of fish passes. The report highlights flaws in most of the existing Framwellgate fish passes with recommendations and costs on how to rectify matters.

With the EA still under austerity controls, only limited funding is available and the EA have decided to bid for 2020 funding to improve fish access to the lower weir near to the Archimedes screw, one of the reports principal recommendations. This will entail using stop logs to reduce the flow through the central notch and diverting water to the notch in the weir adjoining the screw which will also be reduced in depth and widened to create easier access. At the same time work will be undertaken to the base of the Larinier fish pass to create more white water in an attempt to draw fish away from entering the screw chamber.

Everything depends on funding of course so let’s hope it happens.