Rising ocean temperatures herald changes in fish populations
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As the hurricane passed over Maine this weekend, the state’s long coastline and ocean became the focus of attention and concern.
New research suggests they are reasons for ongoing concerns about our oceans and the fish that live in them.
Studies say rising ocean temperatures will change where fish, especially large predatory fish, eat and congregate. As a result, fishers and regulators must be willing to change their practices and systems to conserve these species. And to sustain fishing industries and communities that depend on healthy stocks of fish such as tuna and swordfish.
Habitat loss could push some of the most commercially important seafood species out of the ocean, AP reporter Patrick Whittle wrote.
A recent study by Woods Hole Oceanographic Institution in Massachusetts predicts that some large species could lose 70 percent of their habitat by 2100.
“It’s a sign that this year’s high temperatures are not an anomaly but a warning about what the ocean’s future could hold with climate change,” Whittle wrote.
Commercial fishing is an important part of the state’s economy. Last year, Maine’s seafood harvest was worth more than $574 million. The bulk of that came from the state’s lobster harvest of about 100 million pounds, by far Maine’s most lucrative fishery.
Although the studies included in the AP reporting did not involve crayfish, other research predicts impacts on the crustaceans as waters in the Gulf of Maine warm. For example, there is evidence that prime lobster habitat is shifting northward as ocean temperatures rise. The state’s lobster catch has declined significantly in the past decade.
“More and more lobsters are emerging as indicator species for the effects of global warming and ocean warming,” author Chris White said in 2019. “You can argue back and forth about how many different factors influence harvest declines each year – and there are a number of factors, but the biggest one is rising ocean temperatures.
Land and ocean temperatures are rising. This summer was the hottest on record globally, according to NASA. The temperatures, measured at tens of thousands of locations around the world, exceeded previous records by the largest amount since record keeping began in 1880, the agency said Thursday.
Exceptionally high sea surface temperatures have led to record high temperatures. In July, ocean temperatures were about 2 degrees above average for that month.
Although researchers attribute some of these anomalies to the current El Niño weather pattern, greenhouse gas emissions from human activities also play an important role.
“In the long term, we’re seeing more heat and warmer sea surface temperatures almost everywhere,” Gavin Schmidt, director of NASA’s Goddard Institute for Space Studies, said last month. “This long-term trend is almost entirely attributable to human influence — the fact that we have been putting such an enormous amount of greenhouse gases into the atmosphere since the beginning of the industrial age.”
As ocean temperatures continue to rise, it is clear that there will be significant impacts on the entire marine food chain. As fish populations change, it will impact commercial catches – both baitfish and fish that end up on dinner plates – and the people and communities that depend on them. Understanding these changes and planning for them now can help reduce negative consequences.