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Where did the cod come from?

A new genetic analysis of Pacific cod has identified more than 6000 genetic markers, and demonstrates that their DNA diverges steadily with distance, which is termed “isolation by distance”. The results allow researchers to identify where Pacific cod are caught to within 220 km, even if the unknown Pacific cod come from a population that was not included in the original analysis. 

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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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Centennial Story 15

Chang-Ik Zhang (PhD, 1987)
Chang-Ik Zhang started his studies at the University of Washington in 1981 and received a PhD in fisheries under Donald Gunderson in 1987. During his UW graduate studies, he received the Ellis Memorial Scholarship and the Anderson Memorial Scholarship. He was on the Dean’s List for 1985–1986 due to his academic achievements at UW. While a graduate student, he worked with classmates, Patrick Sullivan, now a professor at Cornell University, and Anne Hollowed, now at NOAA/Fisheries, writing scientific papers for publication and discussing scientific issues. 

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Centennial Story 14

Suam Kim (PhD, 1987)
Suam Kim received his B.Sc (1976) and M.Sc. (1979) in the Department of Oceanography from the Seoul National University (Republic of Korea) and his PhD in fisheries oceanography in the School of Fisheries (now SAFS) in 1987. His main research interest at the UW, conducted in collaboration with scientists at the Alaska Fisheries Science Center, was the recruitment process for walleye pollock in the Gulf of Alaska. 

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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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