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243 posts in Publications

Polar bears gorged on whale carcasses to survive past warm periods, but strategy won’t suffice as climate warms

Polar bears scavenge on the carcass of a dead bowhead whale that washed ashore on Wrangel Island in Chukotka, Russia.Chris Collins/Heritage Expeditions

A new study led by the University of Washington found that although dead whales are still valuable sources of fat and protein for some polar bears, this resource will likely not be enough to sustain most bear populations in the future when the Arctic becomes ice-free in summers, which is likely to occur by 2040 due to climate change. The results were published online Oct. 9 in the journal Frontiers in Ecology and the Environment.

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Pinpointing the footprint of trawling fishing vessels on coastal shelves

In recent years there has been a growing debate about what proportion of the oceans is fished, with estimates ranging from well above 50% to just 4%. A new paper now looks at one of the most widespread and damaging fishing types, trawling, where a net is dragged over the sea bottom to capture fish. The new method focuses on shallower continental shelves that are less than 1000 m in depth, finding that the trawling footprint varies hugely across regions from 0.4% of the area to more than 80%, with an average of 14% for all regions examined. 

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High-res data offer most detailed look yet at trawl fishing footprint around the world

A vessel known as a beam trawler sits at the dock in Milford Haven, Wales, United Kingdom.Jan Hiddink/Bangor University

A new analysis that uses high-resolution data for 24 ocean regions in Africa, Europe, North and South America and Australasia shows that 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.

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A superensemble approach for managing data-limited fisheries

Many fisheries around the world are not formally assessed, and for these fisheries it is hard to know whether they are overfished or not, and how much to fish to ensure that fishing remains sustainable. A suite of models has been developed that can be applied to fisheries where the only data available are time series of catches, but there is no information on trends in actual fish numbers. 

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Habitat preservation is a critical part of good ocean fisheries management

School of bluefin tuna

Marine fisheries management aims to keep fish populations at sustainable levels while producing seafood. Fisheries that are assessed to be overfished must have their populations rebuilt to sustainable levels by reducing catches to lower levels. Usually the assessment of status relies on a complicated fisheries stock assessment model, sort of like a weather forecast for fisheries, that estimates the level of sustainable catch that can be taken from a fisheries population. 

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Estuary provides refuge after dam removal for bull trout

Bull trout use a bewildering array of strategies to aid in their survival, from remaining in streams their whole lives, like rainbow trout, to spending part of their lives in the ocean before returning to streams to spawn, just as salmon do. Bull trout are present in only one of two neighboring rivers in the Olympic peninsula, Washington state, and in this one (the Elwha River), two large dams were removed during the period 2011-2014. 

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How far do river fish move?

For decades, fish researchers believed in Gerking’s “restricted movement paradigm”, thinking that river-dwelling fish largely stay in the same place and rarely venture forth. But in recent decades, ecologists have harnessed the power of both advanced tags and improved genetic methods to directly estimate movement distances and average home ranges of different fish species. Now, a new paper has gathered in one place data from more than 200 direct movement studies and more than 200 genetic studies to estimate how far river fish more on average. 

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Whole DNA sequences should be used to improve conservation decisions

Rusty patched bumblebee (Bombus affinis; photo credit: Johanna James-Heinz), eastern massasauga rattlesnake (Sistrurus catenatus; photo credit: Nick Cairns), and willow flycatcher (Empidonax traillii; photo credit: Kelly Colgan Azar)

The U.S. Endangered Species Act has saved or recovered many species, and is recognized as one of the most powerful laws in the world for protecting the environment. The primary aim of the Act is to ensure that populations and species persist, and to conserve genetic variation in population. But little attention is paid to the adaptive potential of populations—the capability of populations to evolve when faced with new selective pressures—even though new genetic methods of sequencing the entire DNA of organisms are now cheaper and easier than ever before. 

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There are multiple ways of thinking about endangered species classification

To protect and recover species, most countries have laws that mandate particular actions when species are classified as threatened or endangered. These classifications can have an enormous impact on industries that impinge on the species in question, for example the declaration of northern spotted owls as endangered led to large-scale shutdowns in logging on old-growth forests. This process of classifying a species as threatened, endangered, or neither constitutes a difficult decision, and difficult decisions can usefully be approached using the theory and tools of decision analysis. 

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Far smaller fishing footprint than previously believed

Effect of grid resolution on the perception of fishing footprint.

A new and more accurate study reveals that about 4% of the ocean area experiences fishing each year, a far smaller estimate than previous studies that relied on very large grid sizes. Two recent studies estimated that fishing takes place in 55% of the ocean and 90% of the ocean each year. But these estimates divide the ocean into 0.5°×0.5° grid cells, which are ~3100 km² in size at the equator, and assume each cell is fished if a single fishing location is recorded in the entire cell. 

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