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239 posts in Publications

Costs of processing salmon limit the reward for managing predators and prey together

In Chignik, Alaska, sockeye salmon are preyed on when young by coho salmon; the sockeye support a valuable fishery, but coho do not. A simulation exercise examined whether fishers and processors might make more money if coho were reduced by fishing, under different levels of predation of coho on sockeye. Models suggested that fishers would end up with higher harvests, and make more money, but processors would probably not benefit because of the extra costs of processing low-value coho salmon.  

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Dam removal frees fish to feed in the ocean

Bull trout in the Elwha River have been separated from the ocean for a century, but dam removal in 2012-14 has now freed them to head out to the ocean again. Analysis of stable isotope ratios reveals that bull trout now spend substantial time at sea eating marine prey before heading back to the Elwha River to spawn. This re-emergence of a long-lost life history variation after being landlocked for so many decades, shows that fish species can swiftly adapt and change their strategies when new opportunities arise. 

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Revealed: the ups and downs of sablefish

Sablefish are a highly valuable commercial species that inhabit waters as deep as 750 m in the North-East Pacific. New pop-up satellite tag data now show that they do not stick to the bottom all the time: the majority of tagged fish migrate hundreds of meters up and down in the water column every day. The upward migration occurs at night and is likely because the sablefish are chasing their prey of fish, krill and squid, which are migrate vertically. 

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Salmon face the opposing forces of fishing selection and natural selection

A 100-year simulation of individuals reveals the opposing forces that fisheries and natural selection play in sockeye salmon in Bristol Bay, Alaska. Natural selection favored the production of longer salmon, but also produced differences between the body type of salmon spawning in shallow streams (where body depth declined) and those spawning in the beaches of large lakes (where body depth increased). 

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Major implications for aquaculture production from the fast-growing science of epigenetics

The expression of DNA can be changed not only by changing the sequence of DNA letters, but also through epigenetics, which involves heritable changes in gene expression, for example by adding methyl groups to parts of the DNA. A new review delves deep into the implications of epigenetics for both fish and shellfish aquaculture to identify key areas of aquaculture where epigenetics could be applied. 

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Identifying fish species using DNA barcodes from multiple areas of DNA

A new method for identifying species from their DNA expands on current “DNA barcoding” methods. In the current DNA barcoding methods, a particular promising section of DNA in the mitochondria of cells is sequenced, and differences in the DNA “letters” used to identify species with high accuracy: for instance, this method is more than 80% accurate for freshwater fish species in the Congo River basin. 

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Selecting the best methods to measure ecological impacts of marine renewable energy

The environment may be altered by marine renewable energy developments, which include offshore wind turbines, surface wave converters, and tidal turbines. To measure their impact, it is crucial to first study pre-development conditions, but indicators tracking these conditions may include variability that can be above and beyond the ability of standard models to characterize. In a new paper, the performance of 13 different types of models is tested, with three particular methods performing well under different conditions: vector regression, random forests, and state-space models. 

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Nearly 400 million people are at higher risk of schistosomiasis because dams stop prawn migration

River prawns eat the snails that harbor schistosomiasis (also known as snail fever or bilharzia), acting as a natural control on the disease. Schistosomiasis is a disease in humans caused by parasitic flatworms, which causes chronic pain and stunted growth, diarrhea, and bloody urine, and if left untreated, liver and kidney failure, infertility, and bladder cancer. The parasite infects river snails, which pass the parasites to humans when they come into contact with water containing the parasites. 

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Some beluga whales are leaving the Arctic later because of changes in sea ice

Some Arctic beluga whales now leave the Arctic 2-4 weeks later because of delayed sea ice formation there. The change happens because the southward migration of beluga whales from the Eastern Chukchi Sea population through to the Bering Sea is determined largely by the date of sea ice formation in the Arctic areas north of Alaska, and sea ice formation is happening later in the year. 

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How to balance food and energy with hydropower dams

Almost 100 hydropower dams are planned on the 2700 mile Mekong River, which is a huge economic driving force and a food source for millions living in Burma, China, Vietnam, Laos, Thailand and Cambodia. While these dams will supply much-needed electricity, they will change the flow patterns on the river, which could impact businesses and food security from fisheries. New research now shows how to solve this tradeoff: regulate water releases from the dams so that there are long periods of low water flow interspersed with pulses of flooding. 

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