The Catch of Climate Change: Increased OA and Temperatures Could Directly Impact New England Fisheries and Revenues

Nancy Shrodes is a volunteer for the Ocean Conservation Program at the Conservation Law Foundation. She recently graduated from Tufts University (class of 2011), majoring in Environmental Science with a focus in marine biology.

The Catch of Climate Change is an exclusive Talking Fish series that will look at the potential impacts of ocean acidification from climate change on New England’s oceans and fisheries. This post is the third in the series. Read the previous post here.

Atlantic sea scallops hot on the skillet (Photo credit: NOAA)

New England is known for its fresh and savory seafood, and the fishing industry is a vital source of jobs and income for local economies. But challenges presented by climate change – ocean acidification and increased ocean temperatures – could have major economic consequences for New England fishing ports.

One coastal community that relies on fishing is New Bedford, which is currently the top-earning fishing port in New England. Furthermore, in 2009 New Bedford was ranked as the top-earning U.S. port with commercial fishery revenues of $249.2 million (NMFS statistics).  New Bedford’s commercial success has been in large part due to its profitable scallop fleet, which is its highest grossing species without fail.

Evidence of reduced growth in Atlantic scallops under conditions of increased acidification (Photo credit: Stony Brook University)

Scallops, in addition to other shelled mollusks (like clams, oysters, and mussels), are directly threatened by ocean acidification. Mollusks are particularly vulnerable during their developmental stages and have shown decreased rates of calcification (shell-making), growth, and survival.[1]^,[2],[3],[4] One study compared preindustrial pH levels to today’s, as well as to predicted future levels, and it demonstrated that the effects of OA can already be seen in current Atlantic scallop populations, which are smaller than those reared under preindustrial conditions. The study also showed that scallops grew to be much smaller under future acidic conditions projected to occur at the end of this century. Moreover, the scallops developed weaker, damaged shells and hinges, inhibiting their ability to feed.

Researchers at Woods Hole Oceanographic Institution (WHOI) examined the potential economic consequences of OA on commercial fisheries, which led to eye-opening results. WHOI found that current rates of OA would lead to an estimated 25% loss in mollusk revenues, and that this would decrease New Bedford’s total revenues by $67 million annually, resulting in a net loss of $2.2 billion by 2060 – a staggering amount.[5]

While mollusks are threatened by increasingly acidic ocean conditions, Atlantic cod is threatened by another consequence of climate change: temperature increases. Cod is landed in all of the New England states, and Massachusetts leads the nation in landings of Atlantic cod. In 2009, MA reaped $20.4 million in revenue from cod landings, weighing in at 16 million pounds. In terms of contribution of landing revenues by species to total revenue, revenues from cod were consistently the third-largest contributor to total MA landing revenues from 2007-2009, after scallops and lobster.[6] However, the cod that prosper in the well-suited temperature and environmental conditions of Georges Bank are vulnerable to the increase in sea surface temperature. New Bedford, already facing threats to its scallop industry due to climate change, was specifically listed by the Union of Concerned Scientists (UCS) as a “hot spot” likely to be directly affected by the effects of climate change on cod populations.

Atlantic cod (Photo credit: Hans-Petter Fjeld)

Essentially, ocean warming has already driven cod populations north to colder waters and will only continue to do so. Since 1970, sea surface temperature off of the Northeast has increased by 2°F (1°C).[7] Studies show that the temperature threshold for spawning and juvenile survival is at 47°F (8.3°C), a mean temperature that Georges Bank, one of the region’s most productive fishing grounds, holds today. [8] Young cod can’t withstand much higher temperatures, demonstrating both decreased growth and survival under higher thermal stress.[9] In addition, temperature fluctuations could alter the availability of cod prey. According to the 2007 Northeast Climate Impacts Assessment (NECIA), under a predicted scenario of continued high carbon emissions, Georges Bank won’t be able to support populations of young cod later this century (2070-2099), and will be able to only marginally maintain adult populations, which is bad news for New England fishermen.

Climate change presents many challenges to our oceans that may change population sizes, distribution of fish, availability of prey, and even the odds of survival for various species, altering entire ecosystems. Ocean acidification and temperature increases threaten marine organisms and communities, and those who catch, eat and otherwise value fish should be aware of as well as concerned about this very serious issue.