School of Aquatic and Fishery Sciences

This article originally appeared in UW News

COASST

Though the seabird must eat about half of its body weight in prey each day, common murres are experts at catching the small “forage fish” they need to survive. Herring, sardines, anchovies and even juvenile salmon are no match for a hungry murre.

So when nearly one million common murres died at sea and washed ashore from California to Alaska in 2015 and 2016, it was unprecedented — both for murres, and across all bird species worldwide. Scientists from the University of Washington, the U.S. Geological Survey and others blame an unexpected squeeze on the ecosystem’s food supply, brought on by a severe and long-lasting marine heat wave known as “the blob.”

Their findings were published Jan. 15 in the journal PLOS ONE.

“Think of it as a run on the grocery stores at the same time that the delivery trucks to the stores stopped coming so often,” explained second author Julia Parrish, a UW professor in the School of Aquatic and Fishery Sciences. “We believe that the smoking gun for common murres — beyond the marine heat wave itself — was an ecosystem squeeze: fewer forage fish and smaller prey in general, at the same time that competition from big fish predators like walleye, pollock and Pacific cod greatly increased.”

Jane Dolliver

Common murres nest in colonies along cliffs and rocky ledges overlooking the ocean. The adult birds, about one foot in length, are mostly black with white bellies, and can dive more than two football fields below the ocean’s surface in search of prey.

Warmer surface water temperatures off the Pacific coast — a phenomenon known as “the blob” — first occurred in the fall and winter of 2013, and persisted through 2014 and 2015. Warming increased with the arrival of a powerful El Niño in 2015-2016. A number of other species experienced mass die-offs during this period, including tufted puffins, Cassin’s auklets, sea lions and baleen whales. But the common murre die-off was by far the largest any way you measure it.

From May 2015 to April 2016, about 62,000 murre carcasses were found on beaches from central California north through Alaska. Citizen scientists in Alaska monitoring long-term sites counted numbers that reached 1,000 times more than normal for their beaches. Scientists estimate that the actual number of deaths was likely close to one million, since only a fraction of birds that die will wash to shore, and only a fraction of those will be in places that people can access.

Many of the birds that died were breeding-age adults. With massive shifts in food availability, murre breeding colonies across the entire region failed to produce chicks for the years during and after the marine heat wave event, the authors found.

“The magnitude and scale of this failure has no precedent,” said lead author John Piatt, a research biologist at the U.S. Geological Survey’s Alaska Science Center and an affiliate professor in the UW School of Aquatic and Fishery Sciences. “It was astonishing and alarming, and a red-flag warning about the tremendous impact sustained ocean warming can have on the marine ecosystem.”

COASST

From a review of fisheries studies conducted during the heat wave period, the research team concluded that persistent warm ocean temperatures associated with “the blob” increased the metabolism of cold-blooded organisms from zooplankton and small forage fish up through larger predatory fish like salmon and pollock. With predatory fish eating more than usual, the demand for food at the top of the food chain was unsustainable. As a result, the once-plentiful schools of forage fish that murres rely on became harder to find.

“Food demands of large commercial groundfish like cod, pollock, halibut and hake were predicted to increase dramatically with the level of warming observed with the blob, and since they eat many of the same prey as murres, this competition likely compounded the food supply problem for murres, leading to mass mortality events from starvation,” Piatt said.

David B. Irons

As the largest mass die-off of seabirds in recorded history, the common murre event may help explain the other die-offs that occurred during the northeast Pacific marine heat wave, and also serve as a warning for what could happen during future marine heat waves, the authors said.

UW scientists recently identified another marine heatwave forming off the Washington coast and up into the Gulf of Alaska.

“All of this — as with the Cassin’s auklet mass mortality and the tufted puffin mass mortality — demonstrates that a warmer ocean world is a very different environment and a very different coastal ecosystem for many marine species,” said Parrish, who is also the executive director of the Coastal Observation and Seabird Survey Team, known as COASST. “Seabirds, as highly visible members of that system, are bellwethers of that change.”

Additional UW co-authors are Timothy Jones, Hillary Burgess and Jackie Lindsey. Other study co-authors are from U.S. Geological Survey, U.S. Fish and Wildlife Service, Farallon Institute, International Bird Rescue, Humboldt State University, National Park Service, NOAA Fisheries, Moss Landing Marine Laboratories, NOAA Greater Farallones National Marine Sanctuary and Point Blue Conservation Science.

This research was funded by the USGS Ecosystems Mission Area, the North Pacific Research Board, The National Science Foundation and the Washington Department of Fish and Wildlife.

For more information, contact Parrish at jparrish@uw.edu and Piatt at piattjf@gmail.com.

This article originally appeared in UW News

Nearly half of the fish caught worldwide are from stocks that are scientifically monitored and, on average, are increasing in abundance. Effective management appears to be the main reason these stocks are at sustainable levels or successfully rebuilding.

That is the main finding of an international project led by the University of Washington to compile and analyze data from fisheries around the world. The results were published Jan. 13 in the Proceedings of the National Academy of Sciences.

“There is a narrative that fish stocks are declining around the world, that fisheries management is failing and we need new solutions — and it’s totally wrong,” said lead author Ray Hilborn, a professor in the UW School of Aquatic and Fishery Sciences. “Fish stocks are not all declining around the world. They are increasing in many places, and we already know how to solve problems through effective fisheries management.”

The project builds on a decade-long international collaboration to assemble estimates of the status of fish stocks — or distinct populations of fish — around the world. This information helps scientists and managers know where overfishing is occurring, or where some areas could support even more fishing. Now the team’s database includes information on nearly half of the world’s fish catch, up from about 20% represented in the last compilation in 2009.

“The key is, we want to know how well we are doing, where we need to improve, and what the problems are,” Hilborn said. “Given that most countries are trying to provide long-term sustainable yield of their fisheries, we want to know where we are overfishing, and where there is potential for more yield in places we’re not fully exploiting.”

Over the past decade, the research team built a network of collaborators in countries and regions throughout the world, inputting their data on valuable fish populations in places such as the Mediterranean, Peru, Chile, Russia, Japan and northwest Africa. Now about 880 fish stocks are included in the database, giving a much more comprehensive picture worldwide of the health and status of fish populations.

Still, most of the fish stocks in South Asia and Southeast Asia do not have scientific estimates of health and status available. Fisheries in India, Indonesia and China alone represent 30% to 40% of the world’s fish catch that is essentially unassessed.

“There are still big gaps in the data and these gaps are more difficult to fill,” said co-author Ana Parma, a principal scientist at Argentina’s National Scientific and Technical Research Council and a member of The Nature Conservancy global board. “This is because the available information on smaller fisheries is more scattered, has not been standardized and is harder to collate, or because fisheries in many regions are not regularly monitored.”

The researchers paired information about fish stocks with recently published data on fisheries management activities in about 30 countries. This analysis found that more intense management led to healthy or improving fish stocks, while little to no management led to overfishing and poor stock status.

These results show that fisheries management works when applied, and the solution for sustaining fisheries around the world is implementing effective fisheries management, the authors explained.

“With the data we were able to assemble, we could test whether fisheries management allows stocks to recover. We found that, emphatically, the answer is yes,” said co-author Christopher Costello, a professor of environmental and resource economics at University of California, Santa Barbara, and a board member with Environmental Defense Fund. “This really gives credibility to the fishery managers and governments around the world that are willing to take strong actions.”

Fisheries management should be tailored to fit the characteristics of the different fisheries and the needs of specific countries and regions for it to be successful. Approaches that have been effective in many large-scale industrial fisheries in developed countries cannot be expected to work for small-scale fisheries, especially in regions with limited economic and technical resources and weak governance systems, Parma said.

The main goal should be to reduce the total fishing pressure when it is too high, and find ways to incentivize fishing fleets to value healthy fish stocks.

“There isn’t really a one-size-fits-all management approach,” Costello said. “We need to design the way we manage fisheries so that fishermen around the world have a long-term stake in the health of the ocean.”

Other UW co-authors are Christopher Anderson, Trevor Branch and Ricardo Amoroso of the School of Aquatic and Fishery Sciences. Other co-authors are from University of Victoria, University of Cape Town, National Institute of Fisheries Research (Morocco), Rutgers University, Seikai National Fisheries Research Institute Japan, CSIRO Oceans and Atmosphere, Fisheries New Zealand, Wildlife Conservation Society, Marine and Freshwater Research Center (Argentina), European Commission, Galway-Mayo Institute of Technology, Center for the Study of Marine Systems, Sustainable Fisheries Partnership, The Nature Conservancy, and the Food and Agriculture Organization of the United Nations.

Hilborn and collaborators recently presented this work at the Food and Agriculture Organization of the United Nations’ International Symposium on Fisheries Sustainability in Rome.

The research was funded by the Science for Nature and People Partnership, a collaboration between the National Center for Ecological Analysis and Synthesis at UC Santa Barbara, The Nature Conservancy and Wildlife Conservation Society. Individual authors received funding from The Nature Conservancy, The Wildlife Conservation Society, the Walton Family Foundation, Environmental Defense Fund, the Richard C. and Lois M. Worthington Endowed Professorship in Fisheries Management and donations from 12 fishing companies.

For more information, contact Hilborn at rayh@uw.edu, Parma at anaparma@gmail.com and Costello at costello@bren.ucsb.edu.

More information is available at Sustainable Fisheries UW, an effort to communicate the science, policies and human dimensions of sustainable fisheries.

This article originally appeared in UW News

Killer whales prefer to eat only the biggest, juiciest Chinook salmon they can find. The larger the fish, the more energy a whale can get for its meal.

Each year these top ocean predators consume more than 2.5 million adult Chinook salmon along the West Coast. Except for the endangered southern resident population in Washington, all other fish-eating orca populations that live along the coast, called “residents,” are growing in number. Northern residents along the British Columbia coast number more than 300 whales, for example, while Alaska orcas are close to 2,300 individuals.

But large, old Chinook salmon that orcas crave have mostly disappeared from the West Coast. A new University of Washington and NOAA study points to the recent rise of resident killer whales, and their insatiable appetite for large Chinook salmon, as the main driver behind the decline of the big fish.

The findings were published Dec. 16 in the Proceedings of the National Academy of Sciences.

“We have two protected species, resident killer whales and Chinook salmon, and we are trying to increase abundances of both — yet they are interacting as predator and prey,” said lead author Jan Ohlberger, a research scientist at the UW School of Aquatic and Fishery Sciences. “Killer whales don’t show a lot of interest in Chinook until they reach a certain size, and then they focus intensely on those individuals.”

Chinook salmon are born in freshwater rivers and streams, then migrate to the ocean where they spend most of their lives feeding and growing. Each population’s lifestyle in the ocean varies, mainly depending on what stream they were born in and where they can find food. Washington and Oregon fish often migrate thousands of miles north to the Gulf of Alaska where they feed and fatten up before embarking on their migrations back to rivers in the Pacific Northwest to spawn.

As they return south to spawn in their home streams, Pacific Northwest salmon pass through the feeding grounds of several different killer whale populations, which appear to have a keen affinity for big Chinook. It’s possible these thriving killer whales are essentially stealing a meal from the southern resident orca population, which is struggling to maintain 73 individuals.

“We like to think of the Pacific Ocean as a really big place, but that’s because we are really lousy swimmers. For killer whales and salmon, it’s not a big place,” said co-author Daniel Schindler, a UW professor of aquatic and fishery sciences. While different orca populations avoid each other in the ocean, they inherently overlap their whole lives when competing for the same prey, he explained.

It used to be common to find Chinook salmon 40 inches or more in length, particularly in the Columbia River or Alaska’s Kenai Peninsula and Copper River regions. The average declines in body size — about 10% in length and 25% to 30% in overall weight — could have a long-term impact on the productivity of Chinook salmon populations. Smaller females carry fewer and smaller eggs, so over time the number of fish that hatch and survive to adulthood may decrease.

Resident orcas usually don’t go for Chinook until they reach about 25 inches in length, and they really prefer fish that are over 30 inches long, the researchers said.

The research team analyzed nearly 40 years of data from hatchery and wild Chinook populations from California to Alaska, looking broadly at patterns that emerged over the course of four decades and across thousands of miles of coastline. They analyzed whether fishing pressure played a role in why the biggest Chinook have disappeared, and also considered other factors like changing ocean conditions, and feeding from other marine mammals such as sea lions and seals.

While fishing likely played a role in the decline of large Chinook in the past, fishing pressure since the 1970s has been reduced through more stringent fishery regulations. In the same period, resident killer whales have tripled in abundance.

“Something has to be affecting the survival rates of the oldest fish,” Schindler said. “It’s clear there are lots of unanswered questions, but if you take a weight-of-evidence approach, most arrows are pointing to marine mammals — and killer whales, in particular.”

Still, the researchers caution there are many remaining unknowns, such as why there were so many large Chinook in the past. It’s possible killer whales have a bigger effect now than they did historically, when there were so many more fish in the ocean, explained co-author Eric Ward, a research scientist at NOAA’s Northwest Fisheries Science Center. Declines in the ocean abundance of Chinook salmon as a result of other factors may be intensifying the size-selective effects of orca predation.

“We have seen clear success stories in the rebound of predator species like killer whales,” Ward said. “We’re trying to understand the suite of tradeoffs we face when we have these increases in predator populations.”

The study’s findings reflect a North Pacific ecosystem that is fluid and interconnected, and doesn’t recognize state and national borders, or their associated management practices.

“This study highlights the fact that local management strategies need to be put in a much broader spatial context,” Ohlberger said. “In this case, that means the whole coast, because that’s where the fish migrate.”

Other co-authors are Tim Essington, UW professor of aquatic and fishery sciences, and Tim Walsworth, a former UW graduate student who is now at Utah State University.

This research was funded by the Pacific States Marine Fisheries Commission and the North Pacific Research Board.

For more information, contact Ohlberger at janohl@uw.edu, Schindler at deschind@uw.edu and Ward at eric.ward@noaa.gov.

Reporters who wish to use the MOHAI historical image in this press release must contact MOHAI to determine licensing fees: 206-324-1126 x140 or adam.lyon@mohai.org

This article originally appeared in UW News

Tiny microplastic particles are about as common in the ocean today as plastic is in our daily lives.

Synthetic clothing, containers, bottles, plastic bags and cosmetics all degrade and release microplastics into the environment. Corals and other marine organisms are eating microplastics that enter the waterway. Studies in this emerging field show some harmful effects, but it’s largely unknown how this ubiquitous material is impacting ocean life.

A new experiment by the University of Washington has found that some corals are more likely to eat microplastics when they are consuming other food, yet microplastics alone are undesirable. Two coral species tested responded differently to the synthetic material, suggesting variations in how corals are adapting to life with microplastics. The study was published Dec. 3 in the journal Scientific Reports.

“The more plastic we use, the more microplastics there are, and the more corals are going to be exposed,” said lead author Jeremy Axworthy, a UW doctoral student in the School of Aquatic and Fishery Sciences. “Our study found that some corals probably won’t eat microplastics and will keep going about their daily business. But some might — and if they happen to be sensitive to warmer ocean temperatures or other stressors, this is just another compounding factor to be worried about.”

Corals are tiny animals that are rooted to the reef or rocks on the ocean floor. They use tentacle-like arms to sweep food into their mouths. Many rely on algae for energy, but most also consume drifting animals for survival.

This study is the first to examine whether corals eat microplastics when exposed to warmer water, which is expected to accelerate with climate change. Rising ocean temperatures can be deadly for coral: warm water stresses them, causing corals to lose their symbiotic algae partner that undergoes photosynthesis and provides energy for them to survive. When this happens, coral bleaching and eventual death can occur.

But some corals have adapted to bleaching by shifting their diets to feed on tiny marine organisms called zooplankton, which provide an alternate energy source. As they munch on these small animals — often the same size as microplastics — the research team wondered whether they also were ingesting plastic fragments.

The experiment shows corals do eat microplastics when they switch to a zooplankton diet, adding one more stressor for corals in a changing ocean environment.

“Microplastics are not as simple as a life-or-death threat for corals — it’s not that black or white,” said senior author Jacqueline Padilla-Gamiño, assistant professor at the UW School of Aquatic and Fishery Sciences. “It’s about total energy lost. If corals constantly are dealing with microplastics, it might not kill them, but there will be less energy for them to grow and to reproduce.”

The researchers collected two species of common corals off the east coast of Oahu, Hawaii, and exposed half of each species to warmer water for several weeks to induce stress and bleaching. Then they ran four different feeding experiments on both bleached and non-bleached corals: corals were fed only microplastics; only a type of zooplankton; microplastics and zooplankton; or nothing.

After dissecting the coral polyps, researchers found that corals stressed by warmer temperatures actually ate much less than their counterparts in normal seawater. This was unexpected and possibly due to stress from high water temperatures. However, one of the two species, known for its voracious eating habits in the wild, consumed microplastics only while also eating zooplankton. Neither coral species ate microplastics alone.

The researchers don’t know why one species of coral readily ate microplastics in the presence of other food, but avoided microplastics when they were the only thing on the menu. They suspect that this species of coral can read certain chemical or physical cues from the plastics and the prey, but might not be able to distinguish between the two when both are present.

It’s also possible the plastic used in this experiment is less desirable to corals, and that plastics with a different chemical makeup could, in fact, be tasty to corals. The researchers plan to test the “tastiness” of other types of microplastics, such as synthetic fibers from clothing.

Ultimately, some coral species likely face greater risks from exposure to microplastics than others, the study found. The researchers will look next at impacts on the physiology of corals that are exposed over a longer period to microplastics.

“Knowing that will provide a lot more context to this work,” Axworthy said. “We need to know the full physiological impacts of chronic exposure to microplastics on corals, especially at increased temperatures, to understand how serious the problem is.”

In the meantime, the problem of microplastics isn’t going away. A 2014 estimate found between 15 and 51 trillion microplastic particles in the oceans, and plastic waste entering the oceans is expected to increase tenfold between 2010 and 2025.

“It’s important when talking about waste management to think big picture — what are we putting in the oceans?” Padilla-Gamiño said. “We don’t know where plastic goes, where it stays, who grabs it, and what are the mechanisms by which we get it back. We are just at the tip of understanding these implications.”

This research was funded by the National Science Foundation.

For more information, contact Axworthy at jeremyax@uw.edu and Padilla-Gamiño at jpgamino@uw.edu.

With 2019 on pace as one of the warmest years on record, a new international study reveals how rapidly the Arctic is warming and examines global consequences of continued polar warming.

The study, published Dec. 4 in the journal Science Advances, reports that the Arctic has warmed by 0.75 degrees C in the last decade alone. By comparison, the Earth as a whole has warmed by nearly the same amount, 0.8 C, over the past 137 years.

“Many of the changes over the past decade are so dramatic they make you wonder what the next decade of warming will bring,” said lead author Eric Post, a University of California, Davis, professor of climate change ecology. “If we haven’t already entered a new Arctic, we are certainly on the threshold.”

What 2 degrees global warming means for the poles

The comprehensive report represents the efforts of an international team of 15 authors, including Kristin Laidre at the University of Washington, who specialize in an array of disciplines, including the life, Earth, social and political sciences. They documented widespread effects of warming in the Arctic and Antarctic on wildlife, traditional human livelihoods, tundra vegetation, methane release, and loss of sea- and land-ice.

“What’s happening in the Arctic is profound and unprecedented,” said Laidre, a UW research scientist at the Polar Science Center and associate professor in the School of Aquatic and Fishery Sciences. “Marine mammals rely on the sea ice platform for most aspects of their life and it is rapidly disappearing. This has cascading impacts on the ecosystem, species interactions, and indigenous humans who rely on these animals for nutritional, cultural and economic purposes.”

Laidre served as the team’s expert on Arctic marine mammals, bringing together the recent literature on profound changes observed related to species and populations, and linking them to other physical and biological components catalogued by other co-authors.

The research team also examined consequences for the polar regions as the Earth inches toward 2 C warming, a commonly discussed milestone.

“Under a business-as-usual scenario, the Earth as a whole may reach that milestone in about 40 years,” said Post. “But the Arctic is already there during some months of the year, and it could reach 2 C warming on an annual mean basis as soon as 25 years before the rest of the planet.”

The study illustrates what 2 C of global warming could mean for the high latitudes: up to 7 C warming for the Arctic and 3 C warming for the Antarctic during some months of the year.

The authors say that active, near-term measures to reduce carbon emissions are crucial to slowing high latitude warming, especially in the Arctic.

Beyond the polar regions

Post emphasizes that major consequences of projected warming in the absence of carbon mitigation are expected to reach beyond the polar regions. Among these are sea level rise resulting from rapid melting of land ice in the Arctic and Antarctic, as well as increased risk of extreme weather, deadly heat waves, and wildfire in parts of the Northern Hemisphere.

“What happens in the Arctic doesn’t stay in the Arctic,” said co-author Michael Mann, a distinguished professor of atmospheric sciences at Pennsylvania State University. “The dramatic warming and melting of Arctic ice is impacting the jet stream in a way that gives us more persistent and damaging weather extremes.”

Other co-author institutions are Aarhus University; University of Oxford; University of Lapland; University of Colorado, Boulder; Chicago Botanic Garden; Dartmouth College; Umea University; University College London; U.S. Arctic Research Commission; Harvard University; and National Oceanic and Atmospheric Administration.

Funding for the study is from the National Science Foundation, Academy of Finland and JPI Climate, National Geographic Society, Natural Environment Research Council, the Swedish Research Council, NASA and NOAA.

This is adapted from a UC Davis news release.