Archive for September, 2017

Sep 21 2017

Authors of Recent Research on Forage Fish Respond to Criticism from Lenfest Task Force

WASHINGTON – September 20, 2017 – In April, a team of respected fisheries scientists led by Dr. Ray Hilborn published a study that found fishing of forage species likely has a lower impact on predators than previously thought. This conclusion challenged previous forage fish research, most notably the 2012 Lenfest Oceans Program report “Little Fish, Big Impact,” which recommended leaving more forage fish in the water to be eaten by predators. 

The Lenfest task force responded to this new research with a Letter to the Editor of Fisheries Research, where the Hilborn et al. study was published. In response to this letter, Hilborn et al. wrote their own letter, which was published August 5 in Fisheries Research and is reproduced below:

Our paper highlighted that key biological relationships between forage fish and their predators were not included in the models used in the LENFEST report. These missing elements were (1) the high level of natural variability of forage fish, (2) the weak relationship between forage fish spawning stock size and recruitment and the role of environmental productivity regimes, (3) the size distribution of forage fish, their predators and subsequent size selective predation and (4) the changes in spatial distribution of the forage fish as it influences the reproductive success of predators. We demonstrate that each of these elements can have a major impact on how one evaluates the impact of fishing forage species on their predators. The LENFEST report used EwE models without these factors to determine the very specific recommendations they made about how to manage forage fish.

We certainly agree that in some cases fishing forage fish will affect their predators, but in other cases there may be little if any impact – it all depends on the biology that was not included in the models used.

This critique of our paper suggests that we are offering alternative evaluation of the impact of fishing forage fish that are, like the LENFEST recommendations, broadly applicable. We make no such claim and much of their critique is against the straw man they have constructed. We are not arguing that fishing forage fish does not affect predators. Rather we show how, in specific cases, there may be little if any impact of fishing forage fish and that general conclusions simply are not possible.

We suggest that the very specific quantitative measures proposed in the LENFEST report result from models that do not have these components and that if these elements were included in the models the conclusions would likely be different. While the authors of the letter argue that they conducted a comprehensive literature review, the specific recommendations came from their modelling, and it is the modelling we criticize and their critique makes few attempts to defend.

We stated “Pikitch et al. (2012) argued forcefully that their analysis provided general conclusions that should be broadly applied. However, relevant factors are missing from the analysis contained in their work…” Their response is that their recommendations were “tailored to the level of uncertainty and data availability of each system.” What we refer as “general conclusions” contain a set of recommendations for three uncertainty tiers, but our point is that the biology of each system is different, not the availability of data or uncertainty, and the differences in biology should be considered when evaluating management options for forage fisheries.

The specificity of their recommendations is clear – for high information situations (which would include the California Current, Humboldt Current, NE Atlantic sand eel and herring) their recommendation is “In any case, lower biomass limits should not be less than 0.3 B0, an MAX F should not exceed 0.75 FMSY or 0.75 M.” These numbers are not the result of their case studies or literature review but the result of their models that did not include a number of important elements.

Finally, we agree that situations where detailed information is lacking are challenging for management, and that is why it is important to identify species and system attributes that make systems less resilient to fishing. Low trophic level species constitute the largest potential sources of increased fish production in the world and much of the recent suggestions for “balanced harvesting” relies on significant increases in exploitation rates on trophic levels associated with forage fish. Since almost all of these potential low trophic level species would be considered in the “low information tier” the LENFEST recommendation is that new fisheries not be allowed until sufficient data are collected. Given that few countries will devote resources to research on fisheries that do not exist, the LENFEST recommendation essentially says no new fisheries on these species, and thus in effect precludes development of what may be significant food resources.

We believe the authors of our paper and the LENFEST report all accept that in some cases predators may be highly dependent on forage fish, but in other cases there may be little dependence. Management should be based upon what is known about the dependence of the predators on forage fish and the relative importance the local agencies place on maintaining high predator abundance verses the benefits of full exploitation of the forage fish. The major forage fisheries of the world are very valuable and currently intensively studied. What is needed for each of these fisheries is a new set of models that incorporate the elements that were missing from the LENFEST analysis.

Ray Hilborn, Ricardo O. Amoroso, Eugenia Bogazzi, Olaf P. Jensen, Ana M. Parma, Cody Szuwalski, Carl J. Walters

Sep 13 2017

California Acting Governor Gavin Newsom Requests Disaster Relief for Sardine, Urchin Fisheries

— Posted with permission of SEAFOODNEWS.COM. Please do not republish without their permission. —

Copyright © 2017

Seafood News


Sardine and sea urchin closures in California have prompted Acting Gov. Gavin Newsom to request fishery failure declarations for both.
Newsom noted in his Sept. 5 letters to U.S. Secretary of Commerce Wilbur Ross that ocean conditions caused the closure for sardines and affected the kelp forest ecosystems on which red urchins depend.

The California Wetfish Producers Association lauded Newsom’s request to Secretary of Commerce Wilbur Ross to approve a declaration of a commercial fishery failure for California’s Pacific sardine fishery. His action was precipitated by La Niña’s cold-water oceanic conditions that are believed to have caused sharply reduced sardine recruitment and the closure of this commercial fishery since 2015.

“This declaration is very important as it will enable California’s historic sardine fishery and its participants to seek federal disaster relief to offset the economic harm fishermen and processors have suffered since the fishery closure,” California Wetfish Producers Association Executive Director Diane Pleschner-Steele said in a statement Tuesday.

The Pacific sardine fishery has been managed under the federal Coastal Pelagic Species Fishery Management Plan (CPS FMP) since 2000. The CPS FMP established a harvest cutoff, prohibiting directed fishing if the sardine population falls below an estimated 150,000 metric tons. Due to low stock assessments, the fishery was closed in 2015 and 2016, and will remain closed in 2017 and possibly even 2018, although sardines have returned to abundance in the nearshore area, where fishing normally takes place.

Certain thresholds have been established that help the National Marine Fisheries Service and Secretary of Commerce make a determination of whether a commercial fishery failure has occurred. One of these involves an analysis of the economic impact and states that revenue losses greater than 80 percent are presumed to be a commercial fishery failure. This is determined by comparing the loss of 12-month revenue to average annual revenue in the most recent five-year period.

“This fishery is historically one of the top 10 highest valued commercial fisheries in California,” Newsom said in his letter regarding the iconic sardine fishery. “Statewide, the commercial closure in 2015 resulted in a total value of $343,148, which is 90 percent less than the 2010-14 average of $3,504,098. That dropped to $95,657 in 2016, which was 96 percent less than the 2011-15 average of $2,711,679.”

The figures for the urchin fishery, particularly in northern California and Orange County, were dire as well.
“The impacts to the regions are evident in the fishery landings data,” Newsom wrote. “In 2016, the northern California fishery ex-vessel revenue fell by 77 percent compared to the 5-year average from $2,587,419 to $604,440, Orange County ports fell by 93 percent from $85,382 to $6,045, and San Diego County ports fell by 48 percent from $574,526 to $297,594.”

Newsom’s letter noted the initial estimates for both fisheries are based on the average ex-vessel value of commercial landings but do not account for additional impacts to seafood processors or related industry businesses that rely on the either or both fisheries.

The sardine fishery is the foundation of California’s wetfish industry, which for decades has produced 80 percent or more of annual statewide commercial fishery landings, until recent years, the CWPA statement said. While fishermen and markets may harvest and process other species in the coastal pelagic species complex, sardines have been the historic mainstay of this industry, and the loss of fishing opportunity has created severe economic impact to both fishermen and processors.

The urchin fishery has been a staple for small-boat fishermen throughout the state for a number of years — until recently.
“Persistent warm ocean conditions that began in 2014 in northern California and 2015 in southern California has affected the fishery in these two regions,” Newsom’s letter said. “In northern California, the warm water event devastated kelp production (93 percent loss of surface kelp canopies compared to 2008 levels), a primary food source for urchins that created persistent starvation conditions. Starvation has led to reductions in the food value of the urchins targeted by the fishery in northern California.

In addition, a population explosion of the less marketable purple sea urchin continues to overgraze the recovering kelp beds, adding further stress to the fishery. In southern California, urchin mortality increased in response to warm El Nino conditions and disease in 2015. This has reduced the numbers of healthy red sea urchins in southern California available to the fishery.”

The Governor’s request for federal declaration now opens the door for fishermen and processors in California’s fisheries to pursue a federal disaster declaration from the Secretary of Commerce and appeal to California’s congressional delegation to pursue legislation allocating funding for disaster relief. Such funds would help alleviate the economic and social harm suffered as a result of these disasters.

Funds could also be used for cooperative research projects, Pleschner-Steele said, such as the collaborative aerial survey of the nearshore area that CWPA participates in with the California Department of Fish and Wildlife in efforts to improve the accuracy of stock assessments.


Sep 7 2017

Sen Sullivan to NOAA: ‘Meaningful Changes’ Needed for Marine Sanctuaries and Monuments

September 6, 2017 (Saving Seafood) — In a letter last month to NOAA Acting Administrator Benjamin Friedman, Sen. Dan Sullivan (R-AK) called for “meaningful changes” to marine sanctuary and marine national monument designations, particularly in the form of greater stakeholder engagement.

In his letter, Sen. Sullivan, who serves as Chairman of the Senate Subcommittee on Oceans, Atmosphere, Fisheries, and Coast Guard, called the concept of marine sanctuaries and monuments “well-intentioned” but wrote that they had caused challenges for coastal communities across the country, including Alaska’s “robust commercial fishing industry.”

“Fisheries restrictions imposed outside of the process utilized by Regional Fishery Management Councils on these areas are problematic for the communities who rely on access to commercial fisheries,” Sen. Sullivan wrote.

Sen. Sullivan expressed concern that the National Marine Sanctuary Act, while requiring stakeholder engagement, does not require that this engagement be taken into consideration when designating a sanctuary. “This can lead to communities feeling betrayed by the agency when the established sanctuaries are unrecognizable to the localities who spent years working with NOAA to form a mutually beneficial designation and management structure,” he wrote.

Sen. Sullivan also called into question the process by which the president can unilaterally establish national monuments with no stakeholder consultation under the Antiquities Act. He criticized recent presidents for using the national monument process as a “political tool” to “limit access to economically viable resources.”

“This action is often taken at the request of non-affected parties such as environmental groups,” he wrote. “This is problematic when monuments are established without the use of best-available science, absent stakeholder engagement, and inattentive to the economic consequences for local communities.”

On August 24, Secretary of the Interior Ryan Zinke completed a review of national monuments ordered by President Donald Trump. While Secretary Zinke’s full recommendations have not been made public, the AP reported that they include changes to a “handful” of monuments.


Download/Read the full letter here [PDF]



Sep 6 2017

Why eye-popping whale shows off the California coast are the new normal

Peter Winch, a naturalist with the Oceanic Society conservation group, said whales have been especially visible this year because cold ocean upwellings have sprinkled near-shore waters with plankton. The whales swim close to shore for anchovies, which feed on plankton, he said.

“They are taking advantage of anchovy shoals that are numerous around the coast,” Winch said. “The humpbacks have the ability to pick and choose. They can stay out in deeper water and eat krill or they can come in. In the last few years, they have just really clued in on this abundance of anchovies.”


Humpbacks have put on a show this summer inside and outside the Golden Gate — flopping around, waving their flukes and leaping out of the water — a bonanza for whale watchers in tour boats and on dry land that scientists say will remain a regular thing.

The ballet of the behemoths, far from a one-time event, is the result of the humpbacks recovering from near-extinction thanks to an international whaling ban, intense conservation and protection of their breeding grounds.

John Calambokidis, a senior research biologist for the nonprofit Cascadia Research Collective, said the giant cetaceans are swimming off the coast of California in numbers equal to their historic population and extending their range into places where they lived long ago.

“Their numbers reached carrying capacity in the last five years, and that’s when sightings in unusual areas began to occur,” said Calambokidis, who has been studying humpback and blue whales for 35 years.

“It’s a good thing in the sense that it reflects the recovery of humpback whales,” he said. “It’s a bad thing in that some of these coastal areas they are repopulating, like San Francisco Bay, put them in greater conflict with other activities, like noise, ships and recreational boaters.”

Since May, large pods have moved through Monterey Bay, past Pacifica and just beyond the breakers at Stinson Beach. Lucky viewers have spotted humpbacks doing pirouettes and splashing down under the Golden Gate Bridge, near the Channel Islands in Southern California and in Puget Sound in Washington.

The phenomenon is all the more remarkable after record-high temperatures in the Pacific Ocean two years ago unleashed toxic algae that closed down the Dungeness crab fishery and contributed to a huge death toll among seabirds and sea lions.

Peter Winch, a naturalist with the Oceanic Society conservation group, said whales have been especially visible this year because cold ocean upwellings have sprinkled near-shore waters with plankton. The whales swim close to shore for anchovies, which feed on plankton, he said.

“They are taking advantage of anchovy shoals that are numerous around the coast,” Winch said. “The humpbacks have the ability to pick and choose. They can stay out in deeper water and eat krill or they can come in. In the last few years, they have just really clued in on this abundance of anchovies.”

Humpbacks, which have long pectoral fins and distinctive knobby heads, are unique among baleen whales. They are friendly and playful, often interacting with other species, including bottlenose dolphins and right whales, and they have complex vocalizations that sound like singing.

They are known for their acrobatic breaching, in which they lift nearly their entire bodies out of the water before splashing down.

The whales, which can grow to 52 feet long and almost 80,000 pounds, were hunted throughout the 18th and 19th centuries in both the Atlantic and Pacific oceans, reducing the global population by more than 90 percent.

Before 1900, an estimated 15,000 to 20,000 humpbacks lived in the North Pacific. Only about 500 remained in 1966, when the International Whaling Commission finally halted the killing.

Calambokidis said humpback numbers have increased by 7 to 8 percent every year since he began studying them in the 1980s. At least 40,000 of the creatures now live in the world’s oceans — and the North Pacific population is at a historic high.

They have done so well, in fact, that nine of the 14 subspecies that had been listed under the Endangered Species Act since 1970 were taken off the list in 2016 in what one federal official called a “true ecological success story.”

Bay Area residents have been particularly enamored with the species since 1985, when a 40-ton humpback named Humphrey swam through the Carquinez Strait, up the Sacramento River and into a creek near Rio Vista. The Solano County city became the focal point of a whale craze, attracting 10,000 people a day as experts tried desperately to turn around the lost animal — which went back to sea after 25 days.

Whale watchers take photos of the Farallon Islands. Photo: Santiago Mejia, The Chronicle
Photo: Santiago Mejia, The Chronicle | Whale watchers take photos of the Farallon Islands.


The local humpbacks migrate along the California coast past San Francisco on their way to and from their breeding grounds in Mexico and Central America. Unlike gray whales, which generally make a beeline to Alaska, humpbacks move north slowly after giving birth, feeding all along their migration route.

Jared Davis, the captain of the Salty Lady fishing and tour boat, said he and his passengers spotted 50 humpbacks on a trip from San Francisco to the Farralon Islands last month. Boaters there have also seen blue whales, fin whales, orcas, dolphins and porpoises in large numbers this summer.

“When the conditions are good, the whales flourish, and the conditions have been good the last couple of years,” said Davis, who takes people whale watching on the weekend and salmon fishing during the week. “It’s a lot of fun.”

The problem with humpbacks moving close to shore, Calambokidis said, is that boats can hit them or crab pot lines can tangle them up.

A recent study by Point Blue Conservation Science found that ships strike and kill an average of 22 humpbacks a year off the coast of California, Oregon and Washington. About 7,300 vessels pass the Golden Gate every year.

The number of whales entangled in fishing lines off the West Coast has risen sharply in recent years, with 71 cases in 2016 — up from 57 the year before and the most since the National Marine Fisheries Service began keeping records in 1982.

“There has been a dramatic increase in entanglements, particularly in crab pots,” Calambokidis said. The humpbacks, he said, “are arriving earlier in the spring to find prey and feed and that overlaps with the crab fishery.”


A humpback whale dives off the coast of San Francisco. Photo: Santiago Mejia, The Chronicle

Photo: Santiago Mejia, The Chronicle | A humpback whale dives off the coast of San Francisco.

Another long-term threat to the whale resurgence is climate change, though all signs indicate the humpbacks will be back again next year in all their glory.

“It’s not unusual anymore,” Calambokidis said. “Sometimes they will be seen closer to shore because prey is closer to shore and sometimes offshore because the prey is out farther to sea, but humpback sightings will be much more common going forward.”


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Sep 6 2017

Study negates concerns regarding radioactivity in migratory seafood

Study negates concerns regarding radioactivity in migratory seafood Assistant professor Kevin Weng of the Virginia Institute of Marine Science with a dolphinfish or mahi-mahi (Coryphaena hippurus) collected as part of the study of Fukushima-derived radioactivity in large Pacific Ocean predators. Credit: A. Gray aboard FV Aoshibi IV.

When the Fukushima power plant released large quantities of radioactive materials into nearby coastal waters following Japan’s massive 2011 earthquake and tsunami, it raised concerns as to whether eating contaminated seafood might impair human health—not just locally but across the Pacific.

A new study by an international research team shows that those concerns can now be laid to rest, at least for consumption of meat from migratory marine predators such as tuna, swordfish, and sharks.

The team focused on cesium, a silvery metal with a large number of radioactive isotopes. Two of these, 134Cs and 137Cs, form when uranium fuel breaks down in nuclear reactors. The cesium isotopes are of particular concern because they were discharged in large quantities following the disaster, exhibit relatively long half-lives (2.1 and 30 years respectively), and tend to accumulate in the muscle tissues that people like to eat.

However, the team’s sampling of tissues from predatory fishes and other large vertebrates collected across the northern Pacific between 2012 and 2015 revealed no detectable levels of 134Cs, and 137Cs concentrations that were generally consistent with background levels from aboveground nuclear testing during the 1940s and 50s. They collected the animals from waters near Japan, Hawaii, and California.

Lead author Daniel Madigan of Harvard University says, “Our measurements and associated calculations of how much radioactive cesium a person would ingest by eating this seafood shows that impacts to human health are likely to be negligible. For marketed fish to be restricted from trade, the cesium levels would have to be more than 1,600 times higher than in any samples we measured.”

Co-author Kevin Weng, an assistant professor at William & Mary’s Virginia Institute of Marine Science, participated in the study by collecting fish samples in waters around Oahu and a remote seamount. He says, “Go ahead and eat some sushi! Our work shows that radioactivity from the Fukushima disaster is very low in open-ocean vertebrates.”

Study negates concerns regarding radioactivity in migratory seafood Assistant professor Kevin Weng of the Virginia Institute of Marine Science with a bigeye tuna (Thunnus obesus) collected as part of the study of Fukushima-derived radioactivity in large Pacific Ocean predators. Credit: A. Gray aboard FV Aoshibi IV.

Also contributing to the study were Zofia Baumann and Nicholas Fisher of Stony Brook University; Owyn Snodgrass, Heidi Dewar, and Peter Dutton of NOAA’s Southwest Fisheries Science Center; Michelle Berman-Kowalewski of the Channel Islands Cetacean Research Unit; and Jun Nishikawa of Tokai University.

The researchers undertook their analysis partly in response to earlier studies by Madigan and colleagues showing elevated levels of radioactive cesium in bluefin and albacore tuna caught off the California coast shortly after the Fukushima disaster—evidence that these fishes had swum almost 6,000 miles in less than two months. (It took ocean currents more than two years to deliver much-diluted cesium from Fukushima to those same waters.)

Although this early work focused on the utility of cesium isotopes as a happenchance tool that could help scientists characterize migratory patterns among a group of heavily exploited commercial fishes, public attention focused on perceived risks to human health.

“The earlier studies showed extremely low risks from cesium to anyone eating these migratory species, but public concern persisted,” says Weng. That concern also expanded to include not only the species of tuna in which cesium had been measured, but to other fishes, marine mammals, and sharks.

“People were very concerned about North Pacific salmon, halibut and scallops off British Columbia, and sea lions in Southern California,” says Madigan. “There was even information on the Internet that ‘the Pacific is dead’.”

“One goal of our study,” he says, “was to put these perceived risks in context by surveying a broad range of vertebrate species across the entire North Pacific for the presence or absence of Fukushima-derived radiocesium. Our results, which show very low or undetectable levels in these animals, are important both for public perception of seafood safety and for scientific understanding of radionuclide transfer.”

The authors suggest that scientists and funding agencies should look for at least one silver lining in any future nuclear or industrial accidents. “We can and should use future point sources of contamination, radioactive or otherwise, to shed new light on migratory dynamics of pelagic species that are poorly understood, heavily exploited, or of high conservation concern,” says Madigan. “But we would need to act quickly, within that narrow opportunistic timespan.”

Originally posted:

Sep 4 2017

Bait and Switch: Anchovies Eat Plastic Because It Smells Like Prey

Schooling Northern anchovies. Matthew Savoca, CC BY-ND

As you bite down into a delicious piece of fish, you probably don’t think about what the fish itself ate – but perhaps you should. Over 50 species of fish have been found to consume plastic trash at sea. This is bad news, not only for fish but potentially for humans who rely on fish for sustenance.

Fish don’t usually die as a direct result of feeding on the enormous quantities of plastic trash floating in the oceans. But that doesn’t mean it’s not harmful for them. Some negative effects that scientists have discovered when fish consume plastic include reduced activity rates and weakened schooling behavior, as well as compromised liver function.

Most distressingly for people, toxic compounds – such as PBDEs – that are associated with plastic transfer to and bioaccumulate in fish tissues. This finding is troubling because it means these toxic substances could further bioaccumulate in us if we consume fish that have eaten plastic. Numerous species sold for human consumption, including mackerel, striped bass and Pacific oysters, have been found with these toxic plastics in their stomachs too.

It is well known that our plastic trash poses a serious threat to marine animals, but we are still trying to understand why animals eat it.

Typically, research has concluded that marine animals visually mistake plastic for food. While this may be true, the full story is likely more complex. For example, in a recent study with colleagues at the University of California, Davis, we showed that plastic debris may also smell attractive to marine organisms. That study focused on seabirds, but now my co-authors and I have found that plastic trash has a similar effect on anchovies – a critical part of ocean food chains.

A school of anchovies. (Wikimedia, Etrusko25)

Sniffing Out the Role of Smell

Olfaction (smell) is a very important sense for marine animals, including fish. Sharks can smell minute quantities of blood over long distances, which helps them find prey. And scientists believe that salmon’s sense of smell helps them navigate up rivers to the specific tributaries where they were born to spawn. Fish may use their sense of smell in behavioral contexts including mating, homing, migrating and foraging.

We tested the idea that plastic debris might smell attractive to the Northern anchovy (Engraulis mordax), a common schooling fish found off the West Coast of North America. Known as forage fish, anchovies are critically important species, ecologically and economically. Unfortunately, they have also been found to eat plastic in the wild.

Working with anchovies is challenging because they require very specific water conditions and school size to behave normally. They need to be in cold, fast-flowing water in schools of at least 100 individuals. When that happens, the anchovies display their contentment by swimming slowly and directly into the flow of water – a behavior known as positive rheotaxis. Luckily, we were able to collaborate with the Aquarium of the Bay in San Francisco, where they have expertise in keeping these fish happy and healthy.

Anchovies schooling in a tank before being exposed to the odor of plastic debris. (Matthew Savoca. CC BYND)

Our Olfactory Experiment

When we started the experiment we did not know whether adult anchovies used their sense of smell to find food at all, let alone whether smell might lead them to consume plastic. To test our hypothesis that it would, we soaked krill (tiny shrimp-like crustaceans that anchovies eat) or plastic debris and clean plastic in seawater for several hours, allowing the water to take on the smell of the material steeping in it. We then filtered our krill or plastic “tea,” presented it to the anchovy schools, and observed their behavior.

When fish are searching for food in groups, their behavior changes in predictable ways: They clump together near the interesting stimulus and dart around, altering their body position relative to the water current. To compare how anchovies responded to the scents of krill and plastic, we hung a specially designed apparatus with a GoPro camera attached over their tank to film the school’s behavior from above.

In addition to analyzing what anchovies did when they detected these odors, we also filmed their anchovies’ behavior while feeding on krill and when they were presented with control treatments of unscented seawater. This gave us baseline information about the schools’ behavior, which we could compare to their responses when they were presented with the different odors.

Using a combination of automated computer analyses and diligent observer scoring, we evaluated how tightly the schools clumped together and how each fish’s body positioning relative to the direction of water flow changed before and after adding an odor solution to the tank. As we predicted, when the anchovies were feeding, schools became more densely clumped and changed their body positioning so that instead of all the fish facing directly into the oncoming current, their bodies aligned more haphazardly as they searched for food morsels. In the control treatments, with no food or food odors present, we did not observe these changes.

When we injected seawater scented with krill into the tank, the anchovies responded as if they were searching for food – which in this case was not there. And, importantly, when we presented them with seawater scented with odors of plastic debris, the schools responded in nearly the same way, clumping together and moving erratically as they would if they were searching for food. This reaction provided the first behavioral evidence that a marine vertebrate may be tricked into consuming plastic because of the way it smells.

The same anchovies displaying feeding behavior after being exposed to the odor of plastic debris. (Matthew Savoca, CC BYND)

Reducing Plastic Pollution

This research confirms several things. First, we showed that Northern anchovies use odors to locate food. This may sound intuitive, but before we did this study there was scant behavioral evidence that adult forage fish, such as anchovies, sardines and herring, used smell to find food.

Our main finding was that plastic debris is likely confusing for marine consumers because of both its appearance and its smell. That’s a problem, because if plastic looks and smells interesting to fish, it will be very hard for them to discern that is it not food.

This study also suggests that our consume-and-dispose culture is coming back to haunt us via the fish we eat. The next big question that it raises is whether plastic-derived contaminants can be transferred from plastic-eating fish to fish-eating humans.

One way to mitigate the problem is to figure out why animals confuse plastic for prey so frequently, and our research has helped to do that. However, everyone can do something right now about ocean plastic pollution by avoiding single-use plastic items and recycling plastic upon disposal. There is more work to be done, but we know enough now to make substantial headway on this global environmental issue.

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