Catch & Release

The question was recently asked about introducing catch & release for rainbow trout at the Fishery, this was my reply;

We don’t have AGM’s for the rods as we are not a club, we are a listed company which is run by the directors on behalf of the shareholders.
Having said that, we do encourage constructive input from our rods.
A number of years ago I did  initiate a scheme similar to the one you proposed, which I stopped when we had a fish kill at the lake (we lost all our trout).
In conjunction with the EA we concluded that whilst the primary problem was a lack of oxygen during a very hot summer, this was exacerbated by a number of factors.
Such as;

Too many fish in the lake which were unable to cope with the changing conditions and warm weather.

Catch & release having a debilitating effect on the fish. Studies in the U.S. have shown that the primary consideration on the survival rates of returned fish is water temperature.

The argulus further compromising the health of the fish, brown trout seem to be able to cope with this parasite better as it is a native species, unlike the rainbow.

Acting on the advice of the EA & IFM, I introduced the following measures to counteract these problems;

  1. Aerators positioned to provide a safe haven for the fish during the summer.
  2. Closing the lake in June, July & August, you only have to look at the water temperatures recorded to see how warm it is getting. The higher the water temperature the less oxygen it can hold.
  3. Reducing fish stocks as much as possible during the summer to protect the fish that are there, in particular the brown trout.
  4. Providing extra shade for the fish where possible.
  5. To compensate rods for these closures we now open for the remaining nine months of the year.
  6. No catch & release for rainbow trout to ensure, as much as possible, that the existing stock is as healthy as possible and better able to cope with the heat and lice.

It is also why the EA recommended that we remove the carp, because of their oxygen requirements and their feeding habits which disturb the silt adding extra nutrients to the water.

  1. I take weekly readings of the water temperature and oxygen levels, which are displayed in the lodge for the rods to see. A warning indicator is when the oxygen levels become very high due to plants and suspended algae, these same plants produce carbon dioxide in the early hours instead of oxygen, and that is when fish kills occur.
  2. We have an active programme of using plastic piping to collect argulus eggs, which are then replaced every two weeks to allow the sun to kill them off. 

Also bear in mind that a rainbow trout will only last for 3 – 5 years anyway, whereas a brown trout can last 15 – 20 years.

Small trout fisheries in the South of England are an endangered species with many each year converting to coarse fishing or closing altogether. 

You would have noticed that the water at present is lovely and clear but from a management point of view it promises to give us a problem, as the sunlight and mild temperatures are encouraging even earlier weed growth, and hence more oxygen issues likely build up.

We still have catch & release for the brown trout, with the added bonus that these don’t count towards your limit.

Catch & release is great on the river or on larger waters but it is not suitable for our situation.


Manager & Director

Boxmoor Trout Fishery.