Saving Seafood

Study says ocean oscillation changes reduced shellfish landings

November 6, 2018 — For years, Maine shellfish harvesters have been complaining that there are fewer softshell clams while arguing that the diggers who go out on the mud flats aren’t the cause of the problem.

A recent study by researchers from NOAA’s Northeast Fisheries Science Center and the Maryland Department of Natural Resources backs them up on both counts.

According to Clyde L. MacKenzie Jr. of NOAA and Mitchell Tarnowski from the Maryland Department of Natural Resources, between 1980 and 2010, documented landings of the four most commercially important inshore bivalve mollusks along the Northeast coast — eastern oysters, northern quahogs, softshell clams and northern bay scallops — dropped by 85 percent.

The principal cause, they say, was warming ocean temperatures associated with a shift in the North Atlantic Oscillation which resulted in damaged shellfish habitat and increased predation from Maine to North Carolina.

“My first response is that the article confirms what I have been seeing with soft-shell clams over at least the last decade or so,” Brian Beal, a professor of marine ecology at the University of Maine Machias and director of research at the Downeast Institute on Great Wass Island, said last week.

The North Atlantic Oscillation is a fluctuation of atmospheric pressure over the North Atlantic that affects both the weather and the climate along the East Coast, especially in winter and early spring.

According to NOAA, shifts in the oscillation can affect the timing of a species’ reproduction and growth, the availability of microscopic organisms for food and predator-prey relationships.

Over a period of several years, MacKenzie and Tarnowski interviewed shellfish wardens and harvesters along the New England coast, as well as examining landings records and other research in an effort to determine the “true causes” of the precipitous drop in shellfish landings.

Read the full story at The Ellsworth American

Scientists have found a way to predict whether fisheries are vulnerable to climate change

July 29, 2016 — World fisheries have steadily been declining over the past couple of decades, and the trend is continuing today.

Just this April, the United States banned  most Pacific sardine fishing after the fish population declined by 90% over a nine year period.

And now, one of the United State’s fisheries that was once thought to be “indestructible” is in grave danger as well.

New England’s coastal Atlantic cod population used to be able to recover from short-term population drops, but since 2008, the cod fish have been unable to successfully rebound.

Overexploitation by humans is one of the leading causes of the drops in fish populations, according to the National Oceanic and Atmospheric Administration (NOAA). But a new study  places at least part of the blame on the North Atlantic Oscillation (NAO) as well.

The NAO is responsible for causing warmer water temperatures in the North Atlantic by creating basin-wide changes in the intensity and location of the North Atlantic jet stream and storm track. It also affects the normal patterns of heat and moisture, affecting temperature and precipitation patterns. This varying phenomenon is the reason for at least 17% of the New England population loss since 1980. The warmer water temperatures cycle hurt the reproductive processes in fish.

Read the full story from Business Insider 

Cod and climate: North Atlantic Oscillation factor in decline

July 28, 2016 — In recent decades, the plight of Atlantic cod off the coast of New England has been front-page news. Since the 1980s in particular, the once-seemingly inexhaustible stocks of Gadus morhua — one of the most important fisheries in North America — have declined dramatically.

In 2008, a formal assessment forecasted that stocks would rebound, but by 2012, they were once again on the verge of collapse. Two years later, the National Oceanic and Atmospheric Administration instituted an unprecedented six-month closure of the entire Gulf of Maine cod fishery to allow stocks to recover.

While overfishing is one known culprit, a new study co-authored by researchers at UC Santa Barbara and Columbia University finds that the climatological phenomenon known as the North Atlantic Oscillation (NAO) is also a factor. And it contributes in a predictable way that may enable fishery managers to protect cod stocks from future collapse. The group’s findings appear in the journal PLOS ONE.

“In the 1980s, the North Atlantic was stuck in a positive phase of NAO,” said lead author Kyle Meng, an economist at UCSB’s Bren School of Environmental Science & Management. “We show not only that positive NAO conditions diminish a few consecutive cohorts of cod larvae but also that this effect follows a cohort as it matures.”

Read the full story at Science Daily

Overfishing Not Solely to Blame for New England Cod Collapse

July 28, 2016 — Overfishing is a known culprit of the decline of Atlantic cod off the coast of New England but now, a new study co-authored by researchers at UC Santa Barbara and Columbia University has found that the climatological phenomenon known as the North Atlantic Oscillation (NAO) is also a factor. And it contributes in a predictable way that may enable fishery managers to protect cod stocks from future collapse.

“In the 1980s, the North Atlantic was stuck in a positive phase of NAO,” said lead author Kyle Meng, an economist at UCSB’s Bren School of Environmental Science & Management.

“We show not only that positive NAO conditions diminish a few consecutive cohorts of cod larvae but also that this effect follows a cohort as it matures.”

The NAO is a periodic climatic phenomenon that, like El Niño, causes changes in water temperatures, although the mechanism is different and the NAO affects the North Atlantic rather than the Pacific.

Also like El Niño, the NAO may be affected in terms of both strength and frequency by climate change. The researchers found that, since 1980, NAO conditions have accounted for up to 17 per cent of the decline in New England cod stocks.

“The Atlantic cod fishery has been the poster child of fishery science and challenges in the field,” said co-author Kimberly Oremus of Columbia University’s School of International and Public Affairs.

Read the full story at The Fish Site