In the olden days
I joined British Waterways back in 1988 as a fisheries scientist. Despite the best efforts of the then National Fisheries Manager, Tom Leatherland, the culture in those days was not the most fish stock friendly. Working alongside Steve Griffiths in the north and Keith Fisher in the Midlands, it was one of our tasks to change the internal way of thinking when it came to fish stock protection. It was quite a challenge back then, but now I am pleased to say that the objective of professional fish stock protection has become a pretty self-evident reality throughout the Trust.
After more than a quarter of a century of striving by the Trust's fisheries & angling team, we are on the final lap of what has proved a lengthy but worthwhile journey. I am immensely confident that in the next couple of years we can sprint triumphantly to the finishing line, arms aloft with the panache of Mo Farah in his pomp.
And so to the why
It is actually an offence under the Animal Welfare Act to cause fish any unnecessary suffering and harm. An environmentally responsible organisation like the Trust is obliged to make best endeavours to avoid killing fish. Fish matter a great deal to our angling club customers. They need the canals to be stocked with abundant and healthy fish.
Equally significantly, fish are an integral part of the wildlife of the nation's canals. For example, when people talk of the need to encourage kingfishers or otters, what they really referring to is the need to ensure thriving fish stock populations that can then support a sustainable level of predation.
Beware the predators
Leaving fish in situ in shallow water makes them easy prey for their natural predators such a herons, kingfishers, cormorants and the like. But there is another, rather more sinister predator ready to take advantage. Certain unscrupulous members of the species Homo sapiens, to which most of us belong, have been known on more than one occasion to remove fish from a lowered canal with the intention of permanently depriving the Trust of its assets.
Replacing fish does not come cheaply, if the Trust had to replace all its fish we would be looking at writing a cheque out for the sum of around £40 million.
Suffocation, parasites and the risks of ice
Like most other living things, fish need a supply of oxygen for a chemical reaction known as respiration. Left in shallow water this oxygen supply can quickly run out, especially if the temperature is high. When fish are left under ice, vital oxygen cannot pass into the water from the air and likewise carbon dioxide cannot escape. So fish can easily die if the water is shallow.
Back in the winter of 1963, the last of the really cold 20th Century winters, numerous shallow ponds suffered major fish kills as a result of this. When fish become stressed, their immune systems weaken. This gives the natural population of parasites an opportunity to thrive and multiply to dangerous levels, putting the fish population at further risk.
Just flush them through the paddles!
In normal operating conditions small fish do get washed through paddles without any deleterious impact. When water levels start to be lowered during maintenance work, the fish sense this and normally swim upstream as an escape mechanism. If the flow is too dramatic they will be forced downstream. They may get bumped along the canal bed and suffer physical injury when coming into direct contact with hard surfaces e.g. concrete cills below paddles. The physical damage does not normally kill the fish immediately. However, fungal and bacterial infections inevitably gain a hold in the damaged parts of the body over a period of days and weeks. These infections will eventually kill the fish.
Saving the endangered species and removing the non-natives
Many species of fish are protected by law including eels, lampreys and bullheads. All three of these species tend to spend their leisure hours on the canal bed or at home in the mud. The only efficient way of safely rescuing them is to use electrofishing techniques. They simply die if left in the mud for any length of time. The Trust is also obliged under European law to remove non-native fish species as part of our ongoing works. Fish rescues provide a way for us to meet these obligations.
Involving the public in fish rescues
Working alongside our fisheries management contractors, Becca Dent and I have developed a concept known as Fish Rescue Education Days or FREDS as Becca has christened them. Typically this involves a visit to site by local school groups to witness the fish rescue in progress. Under supervision the children actually help us weigh and measure the fish before they are safely returned to the water. Both teachers and pupils alike are usually amazed that the canal contains abundant fish life. Some of these youngsters might be inspired to take up fishing and others probably won't, but without a doubt they are unlikely to forget that you can find lots of fish in a canal.