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256 posts in Publications

Vaccine injection is required to protect sablefish from a common disease in aquaculture

Sablefish is a highly valuable wild-caught fish on the west coast of North America that can also be easily cultured in aquaculture facilities. However, when reared at high densities in pens, disease outbreaks can be a problem, especially a bacteria that causes a disease named furunculosis. A new study examines the effectiveness of a vaccine developed by the company AquaTactics, to test whether this vaccine protects against furunculosis when injected into fish, or when the fish are immersed for one minute in a vaccine solution. 

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How many sensors are needed to cover an area?

Many scientific fields require long-term monitoring of regions using sensors that are fixed in place, such as weather stations or acoustic stations that monitor fish abundance. These sensors produce high-quality streams of data in time, but typically over a small proportion of the study area. A long-standing sampling design problem is calculating how many sensors should be deployed to accurately estimate amounts of monitored variables such as rainfall. 

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Deep secrets of even-year and odd-year pink salmon unveiled by genetics

A new analysis of DNA differences between populations of pink salmon in the North Pacific reveals some fascinating insights into how these populations first arose and how they are related. Pink salmon all come back to spawn exactly two years after their parents spawned, which means that pink salmon coming back in even years (2014, 2016, 2018, etc.) are distinct from those coming back in odd years (2013, 2015, 2017, etc.). 

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Fishing reduces the abundance of fish parasites with complex life cycles

Fishing removes parasite species that rely on multiple hosts, according to a comparison of fish parasites on three fished islands and three unfished islands in the central Pacific. The new research also finds that the positive relationship between parasite diversity and fish diversity is eliminated on fished islands. However, it remains an open question whether the impacts of fishing on parasite species increase or decrease disease in host fish. 

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With warming, polar bears spend less time in their maternal dens

In recent years (2009-2015) polar bears in Baffin Bay come on to land about one month earlier than they did in the 1990s, largely owing to early sea ice breakup. This has reduced the duration of maternity denning by approximately 27 days. Maternity dens are now at higher elevations than they were in the 1990s as pregnant bears seek places with deep snow. 

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Faster method of dealing with uncertainty in fisheries assessments

Complex computer models are used to estimate sustainable catches in fisheries, by finding the best values for dozens or hundreds of variables so that the models explain data such as trends in abundance and the number of fish at each age and length. Traditionally, software packages are used for this kind of model fitting, most commonly a package called AD Model Builder (ADMB), but more recently a package called Template Model Builder (TMB). 

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Some differences between sexes in coho salmon are not linked to sex-determining DNA

A section of DNA in each species determines sex, and it is usually assumed that the many differences between sexes are due to DNA variability in this section. However, fresh evidence suggests that other parts of the genome also contribute to differences between sexes in many species from humans to fruit flies. A new study examines what parts of the DNA result in males and females reaching sexual maturity at different ages in coho salmon, and what influences their growth rates at young ages, finding that indeed there is some sex-specific control over these traits that comes from DNA outside of the sex-determining section of DNA. 

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Deciding how to best save toads from a deadly fungal disease

The deadly fungal disease Bd (Batrachochytrium dendrobatidis) is a major cause of the wave of recent extinctions of frogs and toads, but it is difficult to decide how to best save amphibian populations from its ravages. Now a new framework has been developed that helps managers decide which actions are the most beneficial. A combination of a model of multiple boreal toad breeding sites, and expert judgment, was used to assess 35 possible actions that either preserve habitat, reduce Bd prevalence, or reintroduce boreal toads to areas where they no longer exist. 

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Tracking the pulse of the Earth’s fresh waters

To detect floods and protect fish and other stream critters, warning systems are needed that track river flow. But while these stream gage monitoring systems have been restored to historical levels in the U.S., they are declining globally. A new study highlights trends in stream gage numbers, and pinpoints areas in the U.S. that need additional monitoring because of a combination of floods, droughts, and risk to biodiversity. 

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Predators amplify fluctuations in the numbers of small schooling fish

Forage fish are small and densely schooling fish like herring and sardines, that hang out in the open water and become the perfect food for predatory fish, marine mammals, and birds. One key feature of their population numbers is that they have dramatic boom and bust cycles because of ocean conditions, fishing, and highly variable recruitment (numbers of baby fish produced each year). 

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