Our fish face many threats, with which we are all too familiar. Sewage and agricultural pollution, low flows in rivers, commercial overfishing at sea, and unsustainable predation are the rule rather than the exception. This month I want to highlight the potential impact of a changing climate on fish stocks, and hence on the availability of quality fishing. All serious scientists agree that global temperatures are rising as a result of human activity (burning fossil fuels, cutting down forests and releasing methane from agricultural sources). Even if we take concerted global action, temperatures look set to rise by at least 2 degrees centigrade. This may not sound much, but it will have disastrous consequences for our way of life, and on fish and fishing.
Many people think that climate change will only affect delicate fish like trout and grayling, but it will also have a huge impact on coarse fish as well. One of the biggest threats to carp is Koi Herpes Virus (KHV) and the UK has seen numerous outbreaks of this vicious disease in recent years which have led to fisheries being closed and huge numbers of dead fish being dumped into the ground. KHV thrives in warm water and all the recent outbreaks have coincided with years when summer temperatures have been slightly above average.
Rising temperatures will makes sea levels rise due to the expansion of sea water and melting icecaps, coupled with deeper low pressure systems which lead to storm surges. In recent years, there have been more and more saltwater incursions to the Norfolk Broads, which have led to hundreds of thousands of coarse fish keeling over. These incursions will become far more common in low lying areas and estuaries, which are often the most productive coarse fisheries.
The impact of climate on sea fishing is uncertain. What is certain is that fishing will change as fish migrate to find optimum conditions. It’s likely that warmer waters will cause more poisonous algal blooms, fuelled by fertilisers washed off farmers’ fields. As crops fail, there will also be greater economic and political pressure to exploit fish stocks even more unsustainably to feed a growing global population.
Salmon are already nearing the edge of their natural range in the south of the UK. Rising temperatures, coupled with low flows, could lead to their extinction in Southern England and Wales. Sea survival of salmon has plummeted in the past 40 years from around 30% in the 1970s to a handful of percent today. The truth is we don’t know why, but several years of skinny grilse indicated that the fish were going to sea and not finding the food they had come to expect over millennia due to a warming Arctic Ocean. These fish have survived for millions of years through much bigger climate fluctuations than 2 degrees, but it’s the speed of modern climate change that makes it harder for them to adapt. As they move further north, we lose a heritage and a tradition.
Once famous salmon rivers like the Tamar, Hampshire Avon, Test and Itchen could see their stocks wiped out within the lifetime of young anglers who are just learning the art of speycasting today.
All freshwater fish, and particularly sensitive species such as trout and grayling, will suffer from warmer water in the summer months. As water temperature increases, oxygen levels plummet, and rivers and lakes are much more susceptible to pollution incidents. Rainfall patterns are likely to change, with more intense rainstorms causing damaging floods which destroy fish eggs and wash fish downstream and onto floodplains where they die in the fields. More sporadic rain will probably cause more droughts which concentrate pollutants, reduce dissolved oxygen, reduce the wetted area of riverbed which provides food, and give predators a field day.
To respond to this threat, the Angling Trust has joined the Climate Coalition, which is a group of diverse organisations calling for real action on climate change by governments the world over. Of course, climate change should be of concern to us all because of the impact it will have on our lives in so many ways, but highlighting the potential damage to our precious fish and fishing is a way of demonstrating how far-reaching that impact will be.
We are therefore encouraging anglers to back this campaign to call on governments to help make nature more resilient to climate change by reducing other pressures on natural systems, and to take action to reduce emissions which are causing the world to warm.
We can’t any longer pretend that Climate Change isn’t going to happen, or that we are powerless to prepare for it. We must all take urgent action to stop it being worse than it needs to be.
If you want to get involved in the huge Speak Up rally in London on Wednesday 17th June then please click HERE for more details. Why not go along and speak up for the love of fish and fishing.