Filter Results

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. 

Read more

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. 

Read more

Socially aware seabirds are more likely to find food successfully

Animals that are based on a central place, and head out from their to find food, face an especially daunting problem of finding prey when prey are ephemeral and found in unpredictable places. A new model now shows that colonial seabirds foraging for fish like anchoveta can use social information to help them find their prey. Notably, if outgoing birds track the direction of homeward-bound birds, and follow their path back to their last foraging location, they are more likely to end up in prey-rich places. 

Read more

Which fish are you really eating, and how does that affect conservation?

Up to 30% of the time, the true species being sold or served in restaurants is labeled as something else entirely. A new study gathers data on 43 separate papers that DNA tested fish samples to find the actual species being sold, and compared the truth to the species on the labels. The true species identified by DNA was on average 3% less expensive, but slightly more sustainable than the species listed on the labels. 

Read more

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. 

Read more

Designer river flows can benefit native fish over introduced fish species

A new study shows that dams can be designed to benefit native fish, instead of only harming them. Eighteen years of data were collected about river flow, native fish species, and nonnative fish species in a large dryland river basin in the southwestern US, and then analysed to find the best patterns of water release for native fish species. Remarkably, releasing water from the dams in a designer pattern could produce benefits for native fish species that are even greater than the benefits of mimicking natural river flow patterns. 

Read more

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). 

Read more

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. 

Read more

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. 

Read more

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. 

Read more
Back to Top