Wednesday, 7 December 2016

Donal Hickey: New season unlikely to see ease in depletion of salmon stocks

http://www.irishexaminer.com/lifestyle/outdoors/donal-hickey/donal-hickey-new-season-unlikely-to-see-ease-in-depletion-of-salmon-stocks-433639.html



WHEN the salmon fishing season opens next month, anglers will be on the lookout for signs of a continuing decline in stocks, which have been falling dramatically, writes Donal Hickey.
Inland Fisheries Institute (IFI) has reported the number of fishing passing through counters, in recent years, has been the lowest since 2002.
At this stage, scientists regard climate change as, perhaps, the biggest threat to the wild Atlantic salmon, voicing serious concerns about the Arctic ice melt.
For many decades, we’ve seen pollution, over-fishing and diseases being cited as major threats to the species, which has declined by more than 60% in 40 years.
Not as much is yet known about the effects of climate change, but research shows a rise in water temperatures results in reduced salmon growth and survival.
A drop in ice cover also has adverse effects on salmon habitat.
The biggest impact is on the likely salmon range moving northwards.
Many stocks in traditional salmon fishing areas along the east coasts of the US and Canada have been decimated, but there are still viable stocks in Norway, Russia, and Iceland, according to the World Wide Fund for Nature.
Higher temperatures can also create better conditions for disease-carrying parasites and also reduce the prey on which salmon feed, forcing salmon to travel further for food, with more deaths at sea resulting.
More rainfall arising from climate change means more water drains into waterways, clogging up rivers and, possibly, causing more pollution and siltation.
Scientists are referring to the diminishing albedo effect.
Albedo is a measure of how well the earth’s surface reflects sunlight.
Snow-covered sea ice has a high albedo and reflects 85% of sunlight.
However, the open water exposed as ice melts is darker and absorbs more, reflecting 7%.
The less sunlight is reflected, the more heat the planet absorbs.
Professor Jennifer Francis, from Rutgers University, New Jersey, was quoted recently, in the CarbonBrief website, saying that losing reflective sea ice can, in turn, speed up surface warming.
“As sea ice retreats, sunshine that would have been reflected back to space by the bright ice is instead absorbed by the ocean, which heats up, melting even more ice,” she said.
US researchers are reporting sea ice cover to be at its lowest since they started measuring in 1978.
We are also feeling the effects of what’s happening a long way from Ireland, with the IFI revealing only 5% of salmon which go to sea are returning to rivers to spawn compared to 15%, 30 years ago.
Little wonder salmon are extinct in many rivers.