Fishery experts, fish farmers and fisheries managers from across England and Wales have been meeting with Environment Agency fisheries scientists, as part of a review into how native wild brown trout population can be protected, whilst continuing to stock rivers to meet the needs of anglers, angling clubs and fisheries owners.
Here, Andy Thomas, of the Environment Agency’s Trout & Grayling Fisheries Strategy Steering Group, explains what the current thinking about trout stocking is and why new policies are needed to protect wild brown trout.
Stocking trout is a widely practised and legitimate fishery management tool, and many successful fisheries are regularly stocked to maintain catches, thereby supporting fishery value and benefits for the local economy.
About one million brown trout are released into rivers and lakes every year in England and Wales. Most farmed fish have been subject to long term domestication and are bred for an attractive appearance and rapid growth rates, but are not necessarily well suited to survival in the wild. However, when released into rivers some of these trout will breed with wild stocks, potentially reducing the viability of the population as a whole.
We have a responsibility to make sure the right policies are in place to allow wild trout stocks and the fisheries they support to thrive well into the future, particularly given the predicted changes to our climate. We are now analysing the most up-to-date research and listening to the advice of the leading experts in trout fisheries management to decide whether or not the current stocking policy needs changing.
Four years ago the Environment Agency launched the National Trout and Grayling Fisheries Strategy following extensive consultation. The aim of the strategy is to conserve and improve wild stocks of trout, sea trout, char and grayling, while improving the environment for all types of fisheries for these species in England and Wales. It also aims to enhance the social and economic benefit derived from these fisheries.
The strategy covered a wide range of topics, including water quality, habitat improvement and exploitation; but the most talked about has been the interim policy designed to protect wild brown and sea trout populations from the adverse effects of stocking with domesticated farm reared trout. This policy currently limits the stocking of fertile brown trout and promotes the use of all female sterile brown trout as an alternative. A further option is to use the progeny of locally sourced wild broodstock; although we recognise that this option can be difficult in practice.
Sterile rainbow trout have been a regular feature on our still water game fisheries for a number of years. More recently, the use of sterile female brown trout has gained considerable favour with fish farmers and fishery managers, even on sites where there has been no mandatory requirement.
The rapidly evolving field of genetics has given us a better understanding of the impacts on wild trout fitness from exposure to domesticated farm reared strains. What do we mean by ‘fitness’? Well in a nutshell – the ability of the trout to thrive and reproduce successfully. A loss of genetic variability in wild stocks can be caused when there is widespread interbreeding with fertile farm reared strains. This genetic impact can lead to a range of problems, including for example a reduction in survival of offspring as well as reduced sea survival for sea trout populations. In recent years there has been considerable concern expressed over the impacts on wild salmon stocks from the escape of cage-reared salmon. Exactly the same concerns apply to wild trout stocks, yet we still actively stock fertile farm reared brown trout.
Even without the benefit of scientific investigation, it is hardly surprising that fish selected by the fish farmer over many generations for rapid growth and good looks may not necessarily be well adapted to flourish in the wild. Stock fish produced from some farms may not have had any link with a wild environment for 30 or more generations.
Critics of the strategy have suggested that the genetic effects are purely of interest to the academics and not remotely important to the fishery manager or angler. We believe, however, that most anglers want to see thriving wild stocks of brown trout and we believe that a move to using all female sterile stock fish can make a significant contribution to this goal.
In this debate, we must not forget there are many trout rivers, including some chalk streams, where stocking is a prerequisite in sustaining economically viable fisheries. We fully support the fishery owners and angling clubs in their practice of stocking these fisheries and understand why there is a need. This should not distract us, however, from our desire to also protect wild stocks. Our recommendations reinforce the message that this strategy is, above all else, pro trout and pro trout fishing.
Action is needed now because the adverse genetic impacts are no longer just theory, and are supported by extensive scientific research. Without action the net result is that the capacity of trout stocks to be self-sustaining and adapt to their environment will be reduced. There is strong evidence that even where there has been stocking for over a hundred years there are still some stocks with little or no farm strain genes. If left to there own devices, those domestic traits which do not benefit wild survival will gradually be selected out. Trout are great survivors and are an incredibly adaptable species but we need to support them in every way we possibly can.
When the strategy was first launched, and in recognition of the fact that there were gaps in our knowledge and understanding, we pledged to review the stocking policies following a period of further research carried out by ourselves and other interested parties. The research initiatives looked into a wide range of topics. Professor Andy Ferguson carried out a worldwide literature review into the genetic risks associated with stocking, which pulled together information from more than 300 peer-reviewed scientific papers. In addition to this literature review, we have also drawn on several pieces of work carried out by the Game Conservancy Trust, some in partnership with the Environment Agency, which looked into the impacts on wild trout mediated by the presence of stocked trout, and also the comparative performance of stocking with both fertile and non-fertile trout. There were also angler satisfaction surveys and telephone surveys of long term users of sterile trout.
In analysing and assessing the outputs of all this research we have been helped through discussions and workshops with the nations leading authorities on trout fisheries management and research. We have received considerable input and advice from bodies such as the Salmon and Trout Association, Wild Trout Trust, British Trout Association and others. The various research outputs are available from our web site at www.environment-agency.gov.uk/fishnews
We recognise that there is still some disquiet from those with less experience of using and fishing for sterile stock fish. We understand that some people are anxious about ‘genetic modification’ with regard to triploid trout. Triploid trout can occur naturally, albeit rarely in the wild. Triploid trout only differ from diploid trout in that they have three sets of trout chromosomes per cell rather than two as in the case of diploids. Several different types of fruit and vegetables are triploids and have been widely grown and consumed by all of us for many years.
We are also aware that there are some cost implications for
both producers and buyers and adequate time is required for the trout farming industry to fully prepare for the likely increase in demand. We do believe, however, that our wild brown and sea trout populations are a priceless component of our natural heritage and angling for these fish supports rural economies and needs protection.
It is now decision time. The consensus from the experts is that our wild trout stocks need further protection and must be as fit as possible to ensure long term survival, particularly in light of the threats posed by climate change. We now propose that all future brown trout stocking, with the exception of that in totally enclosed waters with no natural trout production, is restricted to non-fertile fish or fish that have been derived from local wild broodstock. To move towards this position we are proposing two options:
Option 1 proposes mandatory implementation in the medium term (up to 5 years).
Option 2 proposes monitored voluntary implementation in the longer term (over 10 years) switching to a mandatory approach if necessary.
If you are a trout angler we would like to hear your views.
We hope that you will support our proposed position on the wide use of non-fertile trout for stocking and will welcome your views on the way in which we should introduce the new policy and on any other related matters. We recognise that many people want to feel that they can protect and improve our trout fisheries. You may wish to suggest ways in which we, the Environment Agency, can offer further support alongside these measures to improve the benefits from stocking.
Please send us you comments by 30th November 2007, including the name of the river you predominately fish. You can contact us at trout.stocking.review@environment-agency.gov.uk. Or you can write to Dr Brian Shields, Trout Stocking Review, Environment Agency, Richard Fairclough House, Knutsford Road, Latchford, Warrington, Cheshire WA4 1HT. You can also telephone us on 08708 506506 and ask for an information pack.
We will be unable to respond individually to all responses but we will carefully consider and take into account all submissions. We will publish the results of the consultation and our future policy on the Environment Agency’s web site and via a press release in early 2008.
