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86 posts in Research

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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New study reveals why some fisheries are formally assessed and others are not

Catch limits are set for fisheries in the U.S. based on formal fisheries stock assessments: complex models that seek to explain all the available data and make forecasts, similar to the methods used for weather forecasts. However, because there is a shortage of both data and trained scientists, not all fisheries can be assessed every year. A new study finds that assessments are conducted on 59% of fisheries within fisheries management plans, but only 13% of fisheries outside management plans. 

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Freshwater critters rely much less on food originating on land than previously thought

Zooplankton, the living tiny animals in water, are an important component of freshwater food webs, sustaining many freshwater fisheries. It has long been thought that a substantial portion of zooplankton diets come originally from land-based ecosystems, for example from nutrients leaching out of plant matter falling into the water, rather than being based entirely from freshwater sources. Now, a bias has been demonstrated in a key hydrogen-based method used to estimate the land portion of zooplankton diets. 

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Where were the salmon going, and how many should we catch?

Adult salmon are well known to return to the lake or stream where they hatched, to spawn another generation of salmon. In many places, fisheries catch them in the ocean on the way back to spawning, but before it is possible to assign them to a particular population from a stream or lake. A new model now shows a way forward to disentangling catches that come from multiple salmon populations, using genetics and analysis of scales. 

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Career advice for scientists from Prof. Tom Quinn

In a retrospective look back on his career, SAFS professor Tom Quinn reflects on the experiences that have shaped his outlook and his philosophy on science, teaching, and mentoring. His experiences have included driving past defunct vulture-topped nuclear reactors, and waking up with bear prints on the outside of the window above his bed in his cabin in Alaska, together with many years working in the field on the long-term studies (since the 1950s) at the University of Washington’s Bristol Bay field program focused on salmon. 

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Improving genetic methods that estimate migration rates

Estimates of migration are important for understanding and managing natural populations. A statistic known as FST is often used as a measure of the amount of genetic difference expected for a given population size and migration rate. Equations that translate FST into estimates of migration exist but the underlying ideal assumptions often do not apply. Now a new model has been used to test which factors affect FST in a real life example based on Atlantic cod. 

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Seabirds like hanging out in river plumes

When large rivers discharge their water into the sea, this creates a plume of freshwater that is highly variable. A new study that attached tiny satellite tags to seabirds now shows that both shearwaters and murres prefer to forage in plumes created by the massive Columbia River. In particular, they prefer the boundary areas between freshwater and sea water, since this area is where zooplankton and prey fish species are most concentrated. 

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