Increasingly acidic seas pose a serious threat to the sea scallop fishery, a recent collaborative study by the University of Virginia, the Ocean Conservancy, the NOAA Northeast Fisheries Science Center, and the Woods Hole Oceanographic Institution (WHOI) concluded.
“As levels of carbon dioxide increase in Earth’s atmosphere, the oceans become increasingly acidic — a condition that could reduce the sea scallop population by more than 50 percent in the next 100 years under a worst-case scenario,” the study states. Models from the study, which were published recently in the journal PLOS One, combine existing data with several factors that impact the fishery: “future climate change scenarios, ocean acidification impacts, fisheries management policies, and fuel costs for fishermen.” Those factors were modeled out into 256 different possibilities.
Oceans absorb vast quantities of carbon dioxide. Fossil fuel emissions exacerbate what the oceans take in, further acidifying the water. “That acidity can corrode the calcium carbonate shells that are made by shellfish like clams, oysters, and scallops, and even prevent their larvae from forming shells in the first place,” the study states.
The scallop fishery is “healthy and valuable today in part because it is very well managed,” says Scott Doney, a co-author from WHOI and the University of Virginia. “We also used the model to ask whether management approaches could offset the negative impacts of ocean acidification.”
It couldn’t. In every scenario, elevated carbon dioxide levels created acidiferous ocean water. The culprit, the study concluded, was “unabated carbon emissions.”
“Over the next 100 years, under the worst-case ocean acidification impacts,” the study states, “the model’s ‘business-as-usual’ scenario shows a sea scallop decline of more than 50 percent, while a scenario with proactive climate policy shows only a 13 percent reduction.”
The authors of the study surmised only a policy change to curb fossil fuel emissions could alter the onset of a more acidiferous ocean.
Another study led by WHOI found ocean acidification could put the squid fishery at risk too, because tiny bones in squid ears begin to dissolve as seawater becomes more acidic. The bones help squid orient themselves in the water. If they can’t do this properly, they may be more easily picked off by predators, and their stocks may therefore shrink, the study suggested.