School of Aquatic and Fishery Sciences

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. The new work by NOAA scientist Frederick Goetz, and SAFS scientist Andy Jasonowicz and Prof. Steven Roberts, appears in Fisheries Oceanography.

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). On the other hand, fisheries tended to catch larger salmon on average, creating selective pressure towards shorter fish. In addition, natural selection was able to maintain locally adapted populations of salmon in streams and creeks even in the face of fishing and considerable genetic flow among the two salmon populations. The research by former SAFS PhD student Jocelyn Lin, SAFS professors Lorenz Hauser and Ray Hilborn, and Jeffrey Hard of the Northwest Fisheries Science Center, NOAA, appears in the open-access journal Ecosphere.

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. Favorable changes can be induced with no DNA selection, by manipulating the rearing environment or by selecting for epigenetic alterations. In this way, the application of epigenetic knowledge has the potential to substantially affect the productivity and sustainability of aquaculture, as well as upend traditional assumptions about selection practices. The review by SAFS postdoc Mackenzie Gavery and Prof Steven Roberts appears in the open-access journal PeerJ.

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. However, DNA barcoding cannot separate sister species that have only recently diverged. Now, a new method has been developed that looks at 500 sections of DNA, and was shown to separate previously inseparable sister species of mandarin fish (Siniperca spp.). When applied to sister species of rock-climbing gobies (Sicydium spp.), however, there was no genetic divergence, suggesting that these two species may not in fact be different species. The new research was coauthored by SAFS professor Luke Tornabene and is published in the journal Scientific Reports.

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. The findings can be applied to measure baseline conditions for any human intervention in a natural system, not just to the monitoring of new marine renewable energy developments. The research was conducted by SAFS MS student Hannah Linder and Prof. John Horne, together with Eric Ward from the Northwest Fisheries Science Center, and appears in the journal Ecological Indicators.

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. New research now shows that dams halt the migrations of predatory river prawns that would otherwise eat the snail hosts of schistosomiasis, resulting in the snails exploding in abundance, and sharp increases in the disease after damming. In all, 277-385 million people are at increased risk of schistosomiasis because they live in regions where river prawns have been extirpated by dams, suggesting that prawn restoration would reduce their disease burden. The new research was coauthored by SAFS prof Chelsea Wood and appears in Philosophical Transactions B.

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. On the other hand, the beluga population to the east, the Eastern Beaufort Sea population, did not change their migration timing. The research by former SAFS student Dr. Donna Hauser and Prof. Kristin Laidre, and their coauthors, appears in the journal Global Change Biology.

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. The new research appeared on the front cover of Science, and was coauthored by SAFS professor Gordon Holtgrieve, who was part of an international team led by Professor John Sabo at Arizona State University. An accompanying piece by LeRoy Poff and SAFS professor Julian Olden, also in Science, explains why this research is a groundbreaking innovation for designing dams for sustainability. For more, see the University of Washington press release.

Withering syndrome is a disease that strikes abalone species throughout the Northeast Pacific Ocean, and is one of the main drivers of recent population declines. This disease is long-term and chronic and is caused by an infection inside the cells of abalone of tiny bacteria in the order Rickettsiales. A new study examines how three abalone species react to withering syndrome infections at different temperature, finding that cool-water pinto abalone succumb at the lowest temperature (17.3°C), red abalone at an intermediate temperature (18.0°C), and warm-water pink abalone at higher temperatures (18.8°C). Additionally, species that were most closely related to white abalone (pinto abalone) were the most susceptible to withering disease. These results have important implications for the conservation and rebuilding of wild abalone populations given higher sea temperatures expected in the future, and also for the successful rearing of abalone in aquaculture operations in California and Baja California, Mexico. The work was conducted by SAFS PhD student Lisa Crosson and Prof. Carolyn Friedman and appears in the Journal of Invertebrate Pathology, and is highlighted as a major research project funded by California Sea Grant.