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Alaska Pollock Spawning Season May be Earlier Under Climate Change

November 16, 2018 — A new study using an unprecedented 32-year data series reveals that spawning time of Alaska pollock– target of the Nation’s biggest fishery– varied by as much as three weeks over the past three decades in the Gulf of Alaska. The new study found clear evidence that the changes were driven by both climate and fishing.

Changes in spawn timing have major ecological and management implications. Timing is critical to survival of newly hatched fish as it determines the conditions they encounter. Many marine fish, like pollock, are adapted to spawn in time for offspring to meet the rapid increase of their plankton prey in spring. If they arrive too early, there may not be enough food; if they arrive too late, the young fish will have less time to grow and will be small compared to their predators and competitors.

Because most mortality happens during the first few weeks of life for pollock, changes in spawn timing that affect larval survival can strongly affect recruitment success–how many fish are available to the fishery two or three years later.

“To effectively monitor and manage pollock populations, managers need to understand what causes changes in spawn timing. With ongoing warming of the world’s oceans,we need to know how changing climate conditions interact with other processes, like harvesting, to influence spawning time,” says Lauren Rogers, the NOAA Fisheries biologist who led the study.

Toward that end, Rogers’ team investigated how pollock spawn timing has shifted over warm and cool periods and large shifts in age structure in the Gulf of Alaska.

“The strength of our study is comprehensive information from an amazing 32-year time series of larval fish size, age, and abundance, validated with maturation data from spawning females, and combined with at-sea process studies, laboratory experiments, and age readings. Using these resources, we were able to test for effects of climate and age structure on both mean spawn timing and duration, and forecast spawn timing under different scenarios of warming and fishing mortality,” Rogers says.

The Study Produced Two Major Findings

Warmer Temperatures Mean Earlier and Longer Spawning–To a Point

Climate clearly drives variation in spawn timing of walleye pollock, with warmer temperatures leading to an earlier and longer spawning period. However, above a threshold temperature, increased warming had no additional effect on spawn timing.

“Because temperatures are projected to be consistently above that threshold with ongoing ocean warming, our results suggest that pollock spawn timing will become more stable in the future,” says Rogers.

Older, Bigger Mothers Spawn Earlier and Over a Longer Duration

An older spawning population started spawning earlier and over a longer duration than a population of predominantly young spawners, highlighting the importance of older mothers.

This is where fishing comes in: harvesting leads to a younger, smaller population over time. In general, increased mortality reduces the mean age of a population, and this effect is strengthened if older individuals are targeted through size selective harvesting. Besides direct effects of harvesting on age structure, fishing may cause evolutionary change by selecting for reproductive maturation at an earlier age or smaller size.

“Our models suggest that changes in pollock age structure associated with sustainable fishing can shift the mean spawning date to 7 days later and shorten the spawning season by 9 days compared to an unfished population, independent of climate conditions.” says Rogers.

That shift could cause young fish to arrive out of sync with their food in two ways: by decoupling the arrival of first feeding fish larvae from temperature-driven changes in plankton production; and by reducing the window over which young fish are delivered into the ecosystem, thus increasing the risk of mismatch with plankton production.

As age of the spawning population increases, spawning begins earlier (a). Warmer temperatures mean earlier spawning to a point around 4 ℃; above that temperature, spawning time levels out (b).

Spawn Timing and the Future

“Our models suggest that climate change will lead to an earlier, stabilized spawning season in the future.” Rogers says. “What we don’t know is how that will affect synchrony of first-feeding larvae with production of their zooplankton prey in spring.”

Rogers hopes future research will answer that question. “We are looking at ways to evaluate match-mismatch with prey by comparing prey and larval fish production.” She also hopes to develop the model into a practical forecasting tool. “If we could use climate and age composition data to predict spawn timing 3-4 months ahead, the forecast could be used to make sure surveys are optimally timed to coincide with peak spawning periods.”

Climatic closures: Crabbers file suit over warming waters

November 16, 2018 — On Wednesday morning, Nov. 14, as crabbers in California’s San Francisco Bay prepared for the state’s Dungeness crab opener today, the Pacific Coast Federation of Fishermen’s Associations filed a lawsuit alleging that 30 fossil fuel companies are to blame for the past four years of delayed Dungeness crab seasons and disastrous economic losses. The reason? Ocean warming as a result of fossil fuel consumption.

“We’re taking a stand for the captains and crew, their families, and the business owners that support the fleet,” said Noah Oppenheim, the association’s executive director. “The fossil fuel companies named in our lawsuit knowingly caused harm, and they need to be held accountable. We are seeking to implement measures, at the fossil fuel industry’s expense, that will help crabbers adapt to a world in which domoic acid flare-ups will be increasingly common, and also help those crabbers who suffer financial losses as a result.”

The lawsuit claims that these fossil fuel companies have been aware for nearly 50 years that “greenhouse gas pollution from their fossil fuel products has a significant impact on Earth’s climate, including a warming of the oceans” and that West Coast crabbers, their families and the communities they support have suffered “substantial economic losses due to those lost fishing opportunities.”

“We’re out fishing all the time, and it’s obvious the oceans are getting warmer,” said Crescent City, Calif., crabber John Beardon. “That’s bad for crabs and other fish, and it’s bad for those of us who make a living on the water. The last three years have been really hard. Our community came together and held a fish fry to help our crew members. But fish fries and disaster relief are no solution to these closures we’re now seeing year after year after year.”

This summer, the government allocated $25.8 million in disaster assistance to those affected by the 2015-16 closure of California’s commercial Dungeness and rock crab fisheries. While that funding was welcome, it certainly didn’t solve the problems of commercial fishing families coming off a series of tough seasons. Oppenheim said that that the 2015-16 closure cost the industry $110 million in lost revenue.

Read the full story at National Fisherman

Climate Change Looms as a Long-Term Threat to Aquaculture

November 16, 2018 — Aquaculture is on the rise in Massachusetts. For many entering the business, shellfish farming seems like a more secure option than the marine fisheries. But climate change looms as a long-term threat over the industry.

Paul Wittenstein always wanted to be a commercial fisherman.

Growing up in Harwich, he worked summer jobs at fish markets and on chartered fishing boats. In college, he started out studying fisheries technology, but it was a bad time for the industry. “All the while I was in school, I was watching the fishing industry struggling,” he said. “I watched the cod disappear. I watched small boats battling big boats. At the same time, I saw this tiny little shellfish industry start to take hold.”

Read the full story on WCAI

New study: Chesapeake oyster decline not due to overfishing

November 14, 2018 — Warmer winters, rather than overharvesting, caused the steep decline of oysters and other commercially valuable shellfish in the Chesapeake Bay and elsewhere along the Atlantic coast, according to a controversial new study that’s getting pushback from some scientists.

The study, which appeared in Marine Fisheries Review, a quarterly journal of the National Oceanic and Atmospheric Administration, says that multi-year stretches of mild temperatures in normally weather months altered the food web in coastal waters. That impaired the growth and reproduction of oysters, quahogs, soft-shell clams and scallops, scientists said. It also led to increased predation on shellfish larvae and outbreaks of diseases.

“The temperatures got warm and that changed the whole environment, so [the oyster diseases] MSX and Dermo could flourish,” said Clyde MacKenzie, Jr., the study’s lead author and a longtime researcher at NOAA’s Northeast Fisheries Science Center at Sandy Hook, NJ. Mitchell Tarnowski, who runs the annual fall oyster survey for Maryland’s Department of Natural Resources, is the co-author.

The paper’s conclusions, especially its dismissal of overfishing as a factor in Chesapeake oyster declines, came under fire from scientists with the University of Maryland Center for Environmental Science and Chesapeake Bay Foundation. Its publication comes as the DNR prepares to release a first-ever stock assessment of the oyster population in the Upper Chesapeake, including an evaluation of whether current harvest levels are sustainable.

The scientific consensus has long been that overharvesting, disease and habitat loss over the decades devastated the Bay’s oyster population, with some estimates putting it in recent years at 1 percent or less of historic levels of abundance. From an annual commercial harvest of nearly 17 million bushels in 1880, landings have trended downward, hitting historic lows in 2003-04 of just 50,000 bushels. The harvest has rebounded some since then, though much of the gain has come via private oyster farming, especially in Virginia.

Read the full story at the Bay Journal

Scientists acknowledge key errors in study of how fast the oceans are warming

November 14, 2018 — Scientists behind a major study that claimed the Earth’s oceans are warming faster than previously thought now say their work contained inadvertent errors that made their conclusions seem more certain than they actually are.

Two weeks after the high-profile study was published in the journal Nature, its authors have submitted corrections to the publication. The Scripps Institution of Oceanography, home to several of the researchers involved, also noted the problems in the scientists’ work and corrected a news release on its website, which previously had asserted that the study detailed how the Earth’s oceans “have absorbed 60 percent more heat than previously thought.”

“Unfortunately, we made mistakes here,” said Ralph Keeling, a climate scientist at Scripps, who was a co-author of the study. “I think the main lesson is that you work as fast as you can to fix mistakes when you find them.”

The central problem, according to Keeling, came in how the researchers dealt with the uncertainty in their measurements. As a result, the findings suffer from too much doubt to definitively support the paper’s conclusion about how much heat the oceans have absorbed over time.

The central conclusion of the study — that oceans are retaining ever more energy as more heat is being trapped within Earth’s climate system each year — is in line with other studies that have drawn similar conclusions. And it hasn’t changed much despite the errors. But Keeling said the authors’ miscalculations mean there is a much larger margin of error in the findings, which means researchers can weigh in with less certainty than they thought.

“I accept responsibility for what happened because it’s my role to make sure that those kind of details got conveyed,” Keeling said.

The study’s lead author was Laure Resplandy of Princeton University. Other researchers were with institutions in China, Paris, Germany and the U.S. National Center for Atmospheric Research and Geophysical Fluid Dynamics Laboratory.

Read the full story at The Washington Post

N.C. governor calls for fishery disaster after Florence

November 14, 2018 — North Carolina Gov. Roy Cooper is seeking additional funding to help coastal communities deal with the damages weathered by the state’s fisheries following Hurricane Florence.

In a letter to Secretary Wilbur Ross, Cooper has asked the U.S. Department of Commerce to declare a federal fishery resources disaster.

“This was the storm of a lifetime for many coastal communities. The damaging economic impact to the state’s fisheries was, and continues to be, significant. While state appropriations will begin to afford some limited initial relief, much more is needed,” Cooper wrote in the letter.

According to the state Division of Marine Fisheries, the North Carolina commercial fishing industry generated more than $96 million in revenue in 2017. Declaring a federal fishery resource disaster can assist with long-term relief for commercial fishing families struggling to make a living while repairing their businesses. Hurricane Florence’s historic rainfall and powerful winds destroyed boats, gear and buildings critical to fishing businesses.

“Federal fisheries disaster assistance can provide the means to a longer-term recovery that North Carolinian fishermen so desperately need,” wrote Cooper.

Read the full story at National Fisherman

Ocean Shock: The climate crisis beneath the waves

November 13, 2018 — To stand at the edge of an ocean is to face an eternity of waves and water, a shroud covering seven-tenths of the Earth.

Hidden below are mountain ranges and canyons that rival anything on land. There you will find the Earth’s largest habitat, home to billions of plants and animals – the vast majority of the living things on the planet.

In this little-seen world, swirling super-highway currents move warm water thousands of miles north and south from the tropics to cooler latitudes, while cold water pumps from the poles to warmer climes.

It is a system that we take for granted as much as we do the circulation of our own blood. It substantially regulates the Earth’s temperature, and it has been mitigating the recent spike in atmospheric temperatures, soaking up much of human-generated heat and carbon dioxide. Without these ocean gyres to moderate temperatures, the Earth would be uninhabitable.

In the last few decades, however, the oceans have undergone unprecedented warming. Currents have shifted. These changes are for the most part invisible from land, but this hidden climate change has had a disturbing impact on marine life – in effect, creating an epic underwater refugee crisis.

Read the full story from Reuters at MSN

Why Is the Gulf of Maine Warming Faster Than 99% of the Ocean?

November 13, 2018 — Late last month, four endangered sea turtles washed ashore in northern Cape Cod, marking an early onset to what has now become a yearly event: the sea turtle stranding season.

These turtles—in last month’s case, Kemp’s ridley sea turtles—venture into the Gulf of Maine during warm months, but they can become hypothermic and slow moving when colder winter waters abruptly arrive, making it hard to escape.

“They are enjoying the warm water, and then all of a sudden the cold comes, and they can’t get out fast enough,” said Andrew Pershing, an oceanographer at the Gulf of Maine Research Institute in Portland, Maine.

Thanks to record-breaking summer water temperatures that quickly transition to cooler conditions, an expanded sea turtle stranding season is just one facet of a new normal for the Gulf of Maine, Pershing explained. And this new normal is a striking contrast to prior conditions.

This year, the Gulf of Maine has experienced only 45 days with what have not been considered heat wave temperatures. Such persistent warmth, scientists warn, can set off a series of other cascading effects on the marine life and fisheries that have historically defined the culture and economy of this region’s coastline.

Read the full story at Earth & Space Science News

Ruling Soon On New England Shrimp Fishery

November 8, 2018 — Fishing regulators are collecting the final comments from the public before deciding whether New England’s shrimp fishery should remain closed for another year.

Scientists and environmentalists have portrayed the shrimp fishery as a victim of climate change, as the warming temperature of the Gulf of Maine has made the shrimp’s habitat inhospitable. The fishery was shut down in 2013.

An arm of the Atlantic States Marine Fisheries Commission was collecting comments about possible new rules for the fishery, should it ever reopen, through 5 p.m. Wednesday. It’s expected to make a decision next week about whether to allow a fishing season in 2019.

Read the full story from the Associated Press at Maine Public

Ocean Shock: Fish Flee for Cooler Waters, Upending Lives in US South

November 7, 2018 — This is part of “Ocean Shock,” a Reuters series exploring climate change’s impact on sea creatures and the people who depend on them.

Creedence Clearwater Revival’s “Fortunate Son” drifts from Karroll Tillett’s workshop, a wooden shed about half a mile from where he was born.

Tillett, known as “Frog” to everyone here, has lived most of his 75 years on the water, much of it chasing summer flounder. But the chasing got harder and harder, and now he spends his time making nets for other fishermen at his workshop, at the end of a dirt path next to his ex-wife’s house.

The house is on CB Daniels Sr. Road, one of several named after two of the fishing clans that have held sway for decades in this small coastal town. Besides CB Daniels Sr. Road, there’s ER Daniels Road and just plain Daniels Road. In Frog’s family, there’s Tink Tillett Road and Rondal Tillett Road.

Once upon a time, these fishing families were pioneers. In the 1970s and 1980s, they built summer flounder into a major catch for the region. The 15 brothers and sisters of the Daniels clan parlayed the business into a multinational fishing company, and three years ago they sold it to a Canadian outfit for tens of millions of dollars.

But for Frog Tillett and almost everyone else in these parts, there’s not much money to be made fishing offshore here anymore.

Forty years ago, Tillett fished for summer flounder in December and January in waters near Wanchese, then followed the fish north as the weather warmed. In recent years, however, fewer summer flounder have traveled as far south in the winter, and the most productive area has shifted north, closer to Martha’s Vineyard and the southern shore of Long Island.

Reuters has spent more than a year scouring decades of maritime temperature readings, fishery records and other little-used data to create a portrait of the planet’s hidden climate disruption — in the rarely explored depths of the seas that cover more than 70 percent of the Earth’s surface. The reporting has come to a disturbing conclusion: Marine life is facing an epic dislocation.

Read the full story from Reuters at Voice of America