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186 posts in Publications

Baby salmon use the earth’s magnetic field to figure out which way is up

Salmon are capable of using the Earth’s magnetic field as a part of their built-in navigating skills to home back to their streams of birth. Now it has been discovered that young salmon emerging from the gravel also use the Earth’s magnetic field to figure out which way is up. Salmon eggs are laid in gravel nests, and the young salmon remain in the gravel until all of the attached yolk reserves are finished, then they emerge to live out in the open water. 

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With sea ice loss, beluga whales make longer and deeper feeding dives in the same places

Satellite tracking devices on beluga whales in the Arctic show how they reacted to far lower sea ice concentrations in recent years. Instead of shifting where they feed, as might have been expected, beluga whales continued to feed in similar (but now largely ice-free) places. However, where dive data were available, their dives were significantly longer and deeper than in years with higher ice concentrations. 

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What is ecosystem-based fisheries management?

The intent of ecosystem-based fisheries management is to move beyond managing each species separately, and to also consider interactions with other species and ecosystem functioning, as well as human benefits such as food, revenue and recreation. A new paper shows that, in practice, people have very different opinions about which management actions could be classed as ecosystem-based. Furthermore, it is highly unlikely that any particular fishery would be able to meet all of the items on a checklist of possible ecosystem-based actions. 

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When do ecological interactions matter in fisheries?

Nearly all fisheries management is based on assessing one species at a time, ignoring any interactions with other species. Many have claimed that including these interactions will improve management and lead to greater fisheries profits. A new paper tests whether precise information on species interactions improves economic performance in fisheries. Somewhat reassuringly, economic value was not markedly lower if managers assumed that an incorrect type of interaction was true. 

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Plastic waste in the oceans is linked to disease in coral reefs

Millions of tons of plastics enter the ocean each year, and many of these end up entangling on coral reefs. Microbes that live on the plastic can then cause coral diseases. A new study appearing in Science today examined more than 100,000 individual corals, finding that only 4% of corals have disease when they are plastic free, but a staggering 89% of corals that are in contact with plastics are diseased. 

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The curious tale of the piranhas that merely eat a few scales off their fish prey

Not all piranhas eat in the feeding frenzies that Hollywood is so fond of depicting. Instead, some species remove and eat just a few scales from their prey. As described in UW News, some of these scale-eaters ram into their unsuspecting prey, while others open their mouths to extraordinary dimensions and use specialized teeth to pry off scales. The wide variety of approaches is captured in a new paper that placed these fish in CT scanners, as part of the Scan All Fish program led by SAFS professor Adam Summers. 

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Forgotten fish naturalist and illustrator remembered in new book

Naturalist Charles Plumier’s work has been resurrected by SAFS Professor Ted Pietsch in a new book Charles Plumier and His Drawings of French Caribbean Fishes. Plumier lived in the era just before Linneaus created his Latin naming system for species names, and as a result, none of Plumier’s detailed painting and descriptions of species were given priority. Prof Pietsch talks in detail about the inspiration for his book with Michelle Ma in an interview posted on UW Today. 

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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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