Scientists looking to understand future ocean acidification effects on commercial fishing (text and video)

The future is now at the Hatfield Marine Science Center.

In the facility’s laboratories scientists are creating conditions to resemble ocean conditions years from now. The goal is to find out how sea life will react to higher levels of ocean acidification that climate change scientists predict will occur in the not-too-distant future.

Since the Industrial Revolution, humans have been pumping more carbon dioxide into the atmosphere. The ocean absorbs a lot of this CO2, raising its level of acidity. It is feared an ocean that is more acidic will negatively affect sea life and, in turn, commercial fishing.

So for those whose livelihoods depend on commercial fishing the scientists’ work is important in understanding what ocean acidification will mean to the fish stocks of the future.

“There is a lot of general concern about the fact that we don’t know a lot about this,” said Lori Steele, the executive director of the West Coast Seafood Processors Association, which is based in Portland. “It’s potentially having an impact, and it’s going to have a much more significant impact, and unless we can really get a handle on it, there’s a potential that fisheries managers aren’t going to be able to do a lot besides controlling fishing.

So researchers at the science center, like Tom Hurst, a fisheries biologist with the National Oceanic and Atmospheric Administration, are trying to find out how ocean acidification will impact commercially important fish species. Hurst’s work focuses on fish found in the waters off Alaska.

Last month he was raising Pacific cod larvae in rows of 16 barrel-like tanks. At the time the larvae were about eight weeks old.

The fish, with the scientific name Gadus macrocephalus, grows to about 58 inches for females and 55 inches for males. The females can weigh up to 55 pounds and the males, 44 pounds. They can live up to 18 years.

The fish is often used in restaurant favorites such as fish and chips.

According to NOAA, the taking of Pacific cod from the ocean is managed by two fishery management plans that control fishing in the Bering Sea/Aleutian Islands and the Gulf of Alaska. The plan dictates things like how many fish can be taken and what gear can be used.

The research that Hurst and others are doing will help formulate these plans for the future.

Some of the tanks in which the larvae live contain the current pH level in the ocean but others have water that has been set to pH levels predicted to exist in the ocean in about 100 to 150 years.

“The goal is to understand how the basic biology of the fish responds to those changes, because it will be hard to see real small incremental changes along the way,” Hurst said.

The research also has the goal of understanding whether the fish stocks in the main fisheries will be become more or less productive in the future.

Throughout their lives in the experiment, Hurst measures the length and weight of the larvae. He’s also looking at how much fat they store and how the food web may change as a result of OA.

“We really don’t know how quickly fishes will be able to adapt to these changes,” he said. “The main concern is that they won’t be able to, because this change is happening more rapidly than any other environmental change in the history of the species.”

Hurst has done other experiments on other species of fish of commercial importance, and he’s found different species react differently to increased OA.

“Walleye pollock, in our observations, seem pretty resistant to the effects of high CO2, whereas the flatfish species – northern rock sole – they appeared to be more sensitive, especially later in life. … They seemed to grow a little bit slower and have higher mortality rates when they’re exposed to the high CO2 levels.”

The scientists are also looking at how OA affects the sensory biology of fish. While scientists have learned that OA prevents shellfish, such as oysters, from forming their shells, they are also beginning to learn that it affects how fish interpret cues that warn them of predators.

“The fishes have the ability to regulate their blood, which corrects part of the pH imbalance that might occur in their blood because of high CO2 or low pH in the environment, but in so doing they cause a change in their blood chemistry, which might affect some of their neurotransmission, and it appears to be manifest in fish by fish misinterpreting sensory signals in their environments,” Hurst said.

In other words, instead of being able to pick up the warning signs of a nearby predator, the fish might instead be attracted to a predator.

While Hurst said there aren’t any direct ways to mitigate the effects of OA, “The idea is that by understanding how productive different fisheries stocks will be in the future, the management organizations and the fisheries can prepare for how productive those things are going to be, so they can plan investments in the fishery.”

Steve Benham, KATU.com, 26 August 2016. Article and video.

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