EACH year, the life that dwells in Tyrone’s rivers and loughs is facing ever-increasing stress from rising fresh water temperatures.
According to Seamus Cullinan, a Loughs Agency fishery inspector, this recent period of intense hot weather has exacerbated the already significant dangers.
Many degrees before temperatures climb high enough to carry serious health risks to humans, the life in local rivers and loughs has long been under severe heat-related stress.
High water temperatures and low water volume have their own inherent dangers, lowering oxygen levels and causing fish to overheat, but they also leave wide open the potential for even more catastrophic outcomes; severe contamination and a widespread fish kill.
Mr Cullinan said, “At present, our waters are extremely low and there is little precedent of these water temperatures.
“We got a reading of 25 degrees Celsius the other day – that’s scary.”
He warned that, at temperatures that high, fish like brown trout, and particularly salmon, were under “critical stress”, and desperately sought refuge in cooler waters.
But cooler waters are not always easily found – where the water is shallow and there are no tree foliage or overhanging vegetation, the heat is virtually inescapable.
Mr Cullinan said, “This combination of high temperatures and low waters causes an extreme reduction in the oxygen levels. Some fish will begin to die at this point.”
Those that don’t mortally succumb to the conditions find themselves in an exhausted state. Struggling on a fisherman’s line can be enough push them beyond the brink.
The fishery inspector said, “In these conditions what well-intentioned catch-and-release fishermen often don’t realise is that; just because you throw the catch back in, doesn’t mean it’s going to survive.
“The fight on the line is often more than the fish can take. This is why we are urging fishermen – of both river and lough – to take some time off until the weather and waters return to a more normal state.”
But there is some news – good weather has promoted cleaner waters.
Mr Cullinan said, “One positive is that because of the low rainfall, fields are dry, and farmers have been able to draw silage and haylage with minimal risk of run-off.”
But his good news comes with a serious caveat – these current conditions also raise the potential of serious contamination and and major fish kill.
“However, because the rivers are so low, it would take very little contamination to wreak very serious consequences – homeowners, farmers and business should all be acutely aware that when they are disposing of anything down drains, or anywhere else, that these materials are destined to end up in the waterways.
“The message is simple: Everyone has to exercise extreme caution when disposing of waste, particularly if that waste contains strong chemicals,” he added.