Proceedings of the National Academy of Sciences Archives

Release of captive-bred native fish negatively impacts ecosystems, study finds

March 8, 2023 — A new study in the Proceedings of the National Academy of Sciences finds that large-scale fish releases negatively impact ecosystems as a whole, while offering little benefit and some harm to the species they seek to support.

For over a century, fisheries and natural resource managers have bred native fish in captivity and then released them, en masse, into the wild. It’s a popular method for supporting commercially important or threatened populations: More than 2 billion captive-bred Pacific salmon were released in the U.S. in 2016 alone.

Unfortunately, the 150-year-old practice may be doing more harm than good, say researchers at UNC Greensboro, Hokkaido Research Organization, Hokkaido University, and the National Institute of Polar Research in Japan.

UNCG freshwater ecologist Dr. Akira Terui, who led the study and whose research focuses on community ecology, was not surprised by his team’s results. “Many resource managers believe that releasing captive-bred native species into the wild is always a good thing,” he says. “However, ecosystems are delicately balanced with regards to resource availability, and releasing large numbers of new individuals can disrupt that. Imagine moving 100 people into a studio apartment—that’s not a sustainable situation.”

Read the full article at PHYS.org

Critique of No-Take MPA Study Published by Nature

July 8, 2022 — Last year, Sala et al. 2021 made waves in both the scientific community and mainstream press with its publication in Nature. The paper claimed that increasing MPAs to stop fishing would lead to more seafood harvest, more biodiversity, and a reduced carbon footprint—a true win-win-win for the ocean. The press release that accompanied the paper highlighted an eye-popping statistic that bottom trawling released more carbon than all airline travel; stories covering Sala et al. 2021 appeared in hundreds of press outlets worldwide.

However, the three computer models used to make each of the “win-win-win” claims have been under increased scrutiny and many scientists doubt their conclusions.

It started with the food provisioning model initially published in the Proceedings of the National Academy of Sciences (PNAS) in 2020. Inexplicable assumptions in the model and several data errors were missed by an inadequate peer review—likely due to a conflict of interest by the PNAS editor. The journal retracted it in October 2021.

You can read the whole breakdown of the retraction and the science of the food model here.

Retractions are rare in science and generally only used in cases of misconduct. Poor science is hardly ever retracted for its flaws—instead, it gets officially criticized and/or updated in the literature.

That process has now started for Sala et al. 2021, with the first official critique (and response) published today in Nature (though several critiques have been available on preprint servers).

The comment, by Ray Hilborn (founder of this site) and Michel Kaiser, points out inconsistent parameters and assumptions and criticizes the overall approach to global MPA science and advocacy.

According to Hilborn and Kaiser, the most severe flaw in Sala et al. 2021 is the inconsistent accounting of fishing effort in the author’s MPA scenarios.

In the carbon and biodiversity model, Sala et al. assumes that when an area is placed into an MPA, the fishing effort that was previously there disappears. But, in the food provisioning model, the paper assumes fishing effort moves to other areas open to fishing. This upwardly biases their claims that MPAs could simultaneously reduce carbon footprint, improve biodiversity, and increase catch:

In their calculations of biodiversity conserved and CO2 emissions reduced, the authors assume that fishing effort disappears, which would decrease total harvest at the point when the MPAs are established. Yet in the base case for the fisheries harvest section, the authors assume that fishing effort moves to areas open to fishing, keeping fishing harvests high.

MPAs certainly reduce fishing effort inside a protected area, but in the real world, fishing effort does not simply disappear—it moves outside the MPA to places where fishing is still allowed. In this scenario, the benefits to carbon emissions and biodiversity presented in Sala et al. would significantly decrease, perhaps even show a net negative response because:

Fishing effort generally goes to places with high catch rates, and if forced to fish elsewhere, more effort is required to achieve the same catch.

In their response to Hilborn and Kaiser, the original authors acknowledge that the attention-grabbing statistic in the press release that bottom trawling releases more carbon into the ocean than all airline emissions would only be true if fishing effort disappears.

Though it garnered big headlines and more attention than any other ocean science paper of the last few years, Sala et al. 2021 does a disservice to marine conservation with its analysis based on incomplete data and erroneous assumptions. Policy that follows its recommendations would potentially waste conservation effort and money on strategies that would not deliver on goals, e.g., proposing a network of MPAs where fisheries are already well managed.

Read the full story at Sustainable Fisheries UW

Shifting ocean closures best way to protect animals from accidental catch

January 18, 2022 — Accidentally trapping sharks, seabirds, marine mammals, sea turtles and other animals in fishing gear is one of the biggest barriers to making fisheries more sustainable around the world. Marine protected areas — sections of the ocean set aside to conserve biodiversity — are used, in part, to reduce the unintentional catch of such animals, among other conservation goals.

Many nations are calling for protection of 30% of the world’s oceans by 2030 from some or all types of exploitation, including fishing. Building off this proposal, a new analysis led by the University of Washington looks at how effective fishing closures are at reducing accidental catch. Researchers found that permanent marine protected areas are a relatively inefficient way to protect marine biodiversity that is accidentally caught in fisheries. Dynamic ocean management — changing the pattern of closures as accidental catch hotspots shift — is much more effective. The results were published Jan. 17 in the Proceedings of the National Academy of Sciences.

“We hope this study will add to the growing movement away from permanently closed areas to encourage more dynamic ocean management,” said senior author Ray Hilborn, a professor at the UW School of Aquatic and Fishery Sciences. “Also, by showing the relative ineffectiveness of static areas, we hope it will make conservation advocates aware that permanent closed areas are much less effective in reducing accidental catch than changes in fishing methods.”

Read the full story at UW News

Study finds Pacific island nations’ livelihood in peril as marine life moves away from tropics

May 7, 2021 — In response to climate change, several marine species are moving away from the equator – something that could jeopardize livelihoods on Pacific island nations that depend on tuna fishing revenue.

According to a study published in the Proceedings of the National Academy of Sciences of the United States of America (PNAS), multiple species studied showed that marine biodiversity on a “global scale” has been responding to the warming climate.

Read the full story at Seafood Source

Even baby fish are eating plastics, Hawaii study finds

November 12, 2019 — Recent evidence has shown that adult fish are eating plastics in the ocean and suffering from perils such as malnutrition and toxicant buildup.

Now, for the first time, a study conducted in Hawaii shows baby fish are ingesting tiny plastics, too.

The research, published today in the journal Proceedings of the National Academy of Sciences, found that both young coral reef fish and open-ocean species are consuming plastic as early as days after they are spawned.

Working in the waters off West Hawaii, an international team of researchers focused on surface slicks — naturally occurring ribbons of smooth water at the ocean surface that are formed when underwater waves converge near coastlines, according to a NOAA news release. These biologically rich ribbons of water aren’t always visible to the eye but are commonly seen, especially if wind conditions are right.

Found in coastal waters around the world, the surface slicks accumulate high concentrations of plankton, a key food source that lures larval fish in huge numbers. These watery nurseries harbor an impressive variety of species from a range of habitats, ranging from the deep ocean waters to shallow-water reefs.

Read the full story at The Honolulu Star Advertiser

Past decisions in seafood management portend future actions, Rutgers study finds

January 23, 2019 — A study led by Rutgers University has shown that the choice to conserve or overharvest renewable resources such as fish is often due to habits and past decisions, which could help fisheries discover why some succeed at conservation and others fail.

The study, “Path-dependent institutions drive alternative stable states in conservation,” was published in Proceedings of the National Academy of Sciences. It showed that conservation is significantly easier to continue once it has already been started.

According to lead author Edward W. Tekwa, those who start conserving can often continue with it, but when conservation is not being practiced, the opposite is true.

Read the full story at Seafood Source

Global Bottom-Trawling Footprint ‘Substantially Overestimated’, According to New Research

October 10, 2018 — About a quarter of the world’s seafood caught in the ocean comes from bottom trawling, a method that involves towing a net along the seabed on continental shelves and slopes to catch shrimp, cod, rockfish, sole and other kinds of bottom-dwelling fish and shellfish. The technique impacts these seafloor ecosystems because other marine life and habitats can be unintentionally killed or disturbed as nets pass across the seafloor.

Scientists agree that extensive bottom trawling can negatively affect marine ecosystems, but the central question — how much of the total area, or footprint, is trawled worldwide — has been hard to nail down.

A new analysis that uses high-resolution data for 24 ocean regions in Africa, Europe, North and South America, and Australasia shows that only 14 percent of the overall seafloor shallower than 1,000 meters (3,280 feet) is trawled. Most trawl fishing happens in this depth range along continental shelves and slopes in the world’s oceans. The study focused on this depth range, covering an area of about 7.8 million square kilometers of ocean.

The paper, appearing in the Proceedings of the National Academy of Sciences, brought together 57 scientists based in 22 countries, with expertise in mapping fishing activity from satellite monitoring and fishing logbook data. It shows that the footprint of bottom-trawl fishing on continental shelves and slopes across the world’s oceans often has been substantially overestimated.

Read the full story at Eco Magazine

Patrice McCarron: Lobstermen’s conservation efforts an investment in the future

February 14, 2018 — KENNEBUNK, Maine — How many of you keep money in the bank? Savings accounts, money market accounts, certificates of deposit or investments – we all use different methods to ensure that we have something set aside for the future. Maine lobstermen have been doing just that for the past century, making sure that there will be lobsters in the Gulf of Maine for their children and grandchildren to harvest. In doing so, they have earned a worldwide reputation as leaders in stewardship of marine resources.

Their conservation practices certainly have paid off, according to a recent paper in the Proceedings of the National Academy of Sciences. Maine’s lobstermen have built one of the world’s most sustainable fisheries by implementing common-sense conservation measures aimed at ensuring that lobsters are able to reproduce before being caught.

It started more than 100 years ago, long before the establishment of extensive government survey programs or sophisticated computer models. Lobstermen began marking female lobsters that were carrying eggs with a notch in their tails, a practice now known as “v-notching.” It was a simple method that let any lobsterman who might catch that female later, without eggs, know to not harvest her order to allow the lobster to spawn again. Since that time, lobstermen have rallied behind other important conservation measures, such as protecting large lobsters, because the bigger the lobster, the more young they can produce. Lobster traps are equipped with vents to allow smaller lobsters to escape and grow to legal size. Only lobster traps, rather than nets, can be used to catch lobsters, a passive gear that ensures that under- or oversized lobsters can be returned to the sea alive.

Read the full story at the Portland Press Herald

New report says future of Maine lobster industry could be worse

January 29, 2018 — ELLSWORTH, Maine — Warming ocean waters will have a big impact on Maine’s $547 million lobster industry in coming years, but the future would look a lot bleaker if not for the conservation efforts of the state’s thousands of lobster fishermen.

According to a study led by scientists at the Gulf of Maine Research Institute, the University of Maine and NOAA Fisheries, conservation practices long advocated by Maine lobstermen are helping make the lobster fishery more resilient to climate change.

For generations, lobstermen in Maine have returned large lobsters and egg-bearing female lobsters to the water rather than keeping them. Lobstermen first marked the tails of the egg bearers with a distinctive “V-notch” to give them further protection.

According to the scientists, these conservation practices, developed by custom and now mandated by state law, distinguish the fishery in the Gulf of Maine, where Maine harvesters trap some 83 percent of all lobster landings, from southern New England, where fishermen historically refused to take the same steps to preserve large, reproductive lobsters.

Funded by the National Science Foundation and published this week in the Proceedings of the National Academy of Sciences, the study shows how warming waters and contrasting conservation practices have contributed to significantly different results in the two fisheries.

Over the past decade (at least until this past year), Maine lobster landings have climbed steadily, setting new records nearly every year. During the same time period, the southern New England lobster population, and lobster fishery, has collapsed.

According to figures compiled by regulators, the commercial lobster landings in Connecticut fell from more than 2.5 million pounds in 1995 to about 200,000 pounds in 2015. In Rhode Island, the catch fell from more than 5 million pounds in 1995 to less than 2.4 million pounds in 2015. In New York, the commercial lobster industry has virtually disappeared.

Led by Arnault Le Bris of the Gulf of Maine Research Institute, the scientists used advanced computer models to simulate the ecosystem under varying conditions. The results show that temperature change was the primary contributor to population changes, but conservation efforts made significant differences in how the lobster population responded.

Read the full story at the Ellsworth American

Research Concludes Maine Conservation Technique Helped Drive Lobster Population Boom

January 24, 2018 — Lobster conservation techniques pioneered by Maine fishermen helped drive a population boom that’s led to record landings this century. That’s the conclusion of new, peer-reviewed research published today.

The paper also finds that lobstermen in southern New England could have used the same techniques to prevent or at least slow the collapse of their fisheries — even in the face of climate change — but they didn’t.

Cape Elizabeth lobsterman Curt Brown has been hauling traps since he was a kid. He says he quickly learned that when he pulled up a female lobster, covered in eggs, he was looking at the fishery’s future.

Maine lobstermen throw back lobsters like these, which produce eggs at a high rate, but other lobstermen do not

“You get used to seeing lobsters and then you see a lobster with eggs and it’s whole new animal,” he says. The underside of the tail is just covered with eggs.”

Since 1917, Maine lobstermen like Brown have used a technique known as “V-notching”: when they found an egg-bearing female in their traps, they would clip a “V” into the end of its tail, and throw it back. The next time it turns up in someone’s trap, even if it’s not showing eggs, the harvester knows it’s a fertile female, and throws it back. Later, the lobstermen also pushed the Legislature to impose limits on the size of the lobster they can keep — because the biggest ones produce the most eggs.

“I use my measure right here, right on the measure, at the end of the measure, is a little tool in the shape of a ‘V,'” Brown says. “So you just grab the lobster underside of the tail just like that and it cuts a V-notch right in the tail. Quick, painless, throw her back in and let her do more of her job.”

And those fertile females have been doing that job very well in Maine. Since the 1980s, lobster abundance here has grown by more than 500 percent, with landings shooting up from fewer than 20 million pounds in 1985, to more than 120 million pounds in 2015 with a value of more than a half billion dollars.

Read the full story at WNPR