Alaska: Heatwave causes large numbers of Salmon deaths

scientists have concluded heatwave and impending climate crisis as the cause of the deaths

Credit : CNN

Several varieties of salmon fishes have inhabited the lakes of Alaska over the years, but the heatwave this summer has endangered the species and has caused die-offs in large numbers.

Earlier this week, locals came across a large number of dead salmons lying along the Yukon river in Alaska. While similar sightings have been reported in various part of the state since mid-July, scientists have concluded heatwave and impending climate crisis as the cause of the die-off.

Life cycle of a salmon comprises of three main stages – they hatch in fresh water, they migrate to oceanic waters for a span of 1-7 years, and finally return to fresh waters to spawn and reproduce. The salmons involved in the die-off were unspawned and showed major signs of suffering from climate change. According to a CNN report, director of the Yukon Inter-Tribal Fish Commission - Stephanie Quinn-Davidson and her team cut open the fishes and found the eggs intact. “They looked for signs of lesions, parasites, and infections, which were however absent and they concluded that the heatwave was responsible for the situation”, the report said.

Salmons at any stage require clean, cold and oxygenated water to survive – cooler the water, smoother the biological development, while warmer water interrupts the development which may lead to death. When the water temperature in Alaska rivers started rising, the salmons’ metabolism sped up triggering them to draw more oxygen from the water. With temperature and oxygen levels in the water being compromised, salmons found themselves in a suffocating environment and were eventually washed off to the shores, says Davidson in an interview with Science Daily.

The World Meteorology Organisation declared earlier this year that June 2019 was the hottest month till date and the repercussions it brings will be severe. One of the consequences was that Alaska, which never crossed the 24-degree Celsius mark before, has now recorded the highest temperature of 27-degree Celsius, thus threatening most of the flora and fauna in and around the state.

This incident in Alaska has also underscored how climate change has affected fishes over the years and what can be anticipated in the future according to research studies and experts.

Owing to climate change, world population of fishes has shrunk down to an alarming 40%, which also includes several extinct species. Scientists are apprehensive that there will be a major negative impact on the environment as well as economies of countries that largely depend on the fishing industry.

Like salmon, metabolism of other fishes - such as sharks, cods, tunas, groupers, haddock and many others, is affected triggering them to draw more oxygen from the ocean waters.  According to Climate News, this has resulted in warming waters losing the availability of oxygen in many parts of the ocean harming their respective ecosystems. Continued efforts to fund and sustain conservation practices that enable different species to adapt to climate change are required.

The same news report also cautions that decline in population of fish could threaten the livelihood and food supplies of millions of people. More than 56 million people worldwide work in the fishing industry. Seafood provides up to half of all animal protein eaten in developing countries as compared to the developed countries. At such a stage, decline in population of fishes will largely impact the economies of such nations too.

Apart from the phenomenon of ‘overfishing’, it can also be predicted that developing countries shall start importing fish from other parts of the world. Not only will this hamper their own economy, but it will also drive up the prices of fishes. “The biggest loss will occur in developing country waters, such as Kiribati, the Maldives and Indonesia, which are at greatest risks due to warming temperatures and rely the most on fish for food security, incomes and employment," said lead researcher Rashid Sumaila, director of the University of British Columbia's Fisheries Economics Research Unit.

Additionally, overfishing may end up putting the population of fish under stress causing them to migrate to unfitting location for inappropriate amount of time. This shall only intensify the negative impacts of climate change, the report states further.

According to William Collin, a researcher of aquatic studies at University of Yorkshire, “Causing a decline and diminishing the fish population harms their reproductive capacity resulting in extinction. This will harm the ecosystems, have negative impact on all living beings directly or indirectly and make us more vulnerable to global warming in the long term. We must understand that even by harming one kind of species, climate change can devastate lives in water, air and on land”.