Fish Refuges and Floating Islands. The Pros & Cons

So you think your fishery has a problem. Catches aren’t what they once were and the regulars have said they’ve seen cormorants in the area so there must be an issue with predation…….

It’s a situation that confronts club committees and fishery managers up and down the country almost every day of the year. The evidence you’ve accrued leads you to the conclusion that fish numbers must be dwindling because your water is too exposed to attacks from above.

Vantage point….

So the answer would seem to be the provision of somewhere for the fish to hide and consequently, the installation of fish refuges and floating islands.

Simple, right?

The reality is that the answer you’re most likely to get from the experts at this stage is no stronger than ‘possibly.’

“They’re certainly not the magic answer to all your problems,” says Angling Trust Fisheries Management Advisor, Richard Bamforth. “Refuges and islands are among a number of options that you could use to improve your water, but fish might be switching off for a number of reasons, not least stocking levels, general water quality, low dissolved oxygen, or indeed harassment from predators, which in turn might leave them more susceptible to disease.”

So you could be losing fish to natural imbalances as much, if not more so than predation. One way to ascertain the truth is to call in the experts before you do anything else. Refuges and islands may well provide part, or perhaps even all the answers but if you’re going to spend vital funds on commercial solutions or precious man-hours creating your own, surely you’ll want to be confident it will be money or time well spent?

“I would be suggesting to someone that their first port of call would be their local Environment Agency fisheries team,” says Richard. “That advice would be free because it’s funded by fishing rod licence income and if their report DOES highlight predation as a problem and suggests refuges, then you can look at ways to move things forward with a bit more confidence.”

Sometimes predation might even be providing natural balance in an over-stocked water and the experts could establish that by advising a netting exercise. But let’s assume the members were right all along and that predation is indeed an issue that requires addressing. The theory behind the installation of refuges and islands is relatively straightforward but the practical application requires careful thought, especially when you consider that the benefits can extend beyond the primary objective

“First and foremost you’re replicating a vegetative environment that fish will aggregate around from a security point of view,” says Paul Coulson who is Director of Operations for the Institute of Fisheries Management. “But there are secondary benefits in that fish will actively spawn on the root systems and vegetation and it’s also good fry habitat too. The plants can also take phosphates and nitrates out the water and there is oxygen transfer from the root systems into the water. There’s also a habitat benefit to terrestrial invertebrates so the benefits can extend wider than those simply enjoyed by the fish.”

One island, many potential benefits

So if you or an advisor concludes that refuges and islands are appropriate for your water, what next? Installing them when conditions require it is one thing, but onward management will be key to their success. In some situations, they can create more problems than they solve.

“You can’t adopt a ‘float and forget’ strategy,” says Paul. I went to one fishery six months after pre-planted floating islands had been installed and then simply left alone. When I got there they were completely and utterly destroyed. The fishery hadn’t considered wave erosion or the local wild fowl and the ducks had simply got on them and used them as a nesting platform. They’d eaten all the plants and when I went, it was simply a succession of squares with some mud on top and a load of ducks.

“Ducks are one thing but what you need to remember is that you can end up offering avian predators a safe platform too. Don’t forget that cormorants aren’t waterproof so they have to get out of the water to dry their wings. If you’re not careful you can do nothing more than provide them with a roost out of reach of human disturbance.”

Cages or mesh can be included above the water level to protect plants from grazing waterfowl and general trampling or roosting pressures while subsurface, an additional cage might offer extra protection to silver fish.

Cages can be wired together to create a ‘reef’

The design of these structures is clearly a consideration, but the other challenge is deciding where to put them. Aesthetically pleasing placement is not the priority here.

“`You have to consider where the fish go,” says Richard Bamforth. “In the winter, they’re more than likely going to go into the deeper water areas. But on some waters, you might need to put them nearer the margins or between the pegs when general marginal work is impossible. If you physically can’t get anything to grow without doing a lot of engineering works you can string them around the margins and the fish will use them. You also have to make sure you use enough. I’ve seen 20-acre waters with two or three installed and while they might have been put in with the best of intentions, they’re pretty much pointless in that size of water.”

On the downside, there are other elements to consider:

  • Floating or submerged versions using the wrong aperture size can create snags, especially for larger fish. This can result in tethered fish and general welfare issues.
  • If not maintained, they can become unsightly.
  • They can be viewed as a hindrance to nettings for stock assessment.
  • They are principally aimed at protecting shoaling silvers.
  • Anglers will fish up to the refuges and then complain when they are snagged or snap off. That of course, will be your fault!

In many cases – and depending on the nature of the water, the better option might be to concentrate efforts on providing a well-balanced, vegetated marginal habitat, but overall, the advice and the considerations all point towards suitable assessment and correct provision before starting any project. Even allowing for all that, improvement needn’t be an expensive process because grant funding might just be available to help. On 17th March, the predation round of the Angling Improvement Fund opens and further details can be found at:

In conclusion, the advice seems to be that refuges and islands don’t offer a single ‘silver bullet’ solution. In situations where they will provide a benefit, support from one of the many commercial suppliers is the obvious ‘go-to’, perhaps fail-safe option. A careful DIY approach to construction remains an alternative, with a nod in the direction of input from the experts being a wise precaution. Whichever option you choose, an initial check on what financial or advisory assistance might be out there, is always a prudent starting point when you start thinking you have a problem.

If you would like advice or assistance from your local Fisheries Officer, contact them by calling 03708 506 506 (Mon-Fri, 8am – 6pm)

If you purchase a licence you are helping to fund the essential work of Environment Agency Fisheries Officers

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