School of Aquatic and Fishery Sciences

Native oysters on the Pacific coast were devastated by commercial overfishing in the 20th century and their recovery has been prevented by water pollution, habitat loss, and possibly ocean acidification. Efforts underway to restore these Olympia oysters rely on harnessing genetic variation among populations to pick the best suited oysters for restoration. Now a new study shows that, even when reared for two generations under the same laboratory conditions, differences among populations persist. Populations differed substantially in how many viable larvae they produced, when they decided to start spawning, and in larval and juvenile growth rates, with faster growth being traded for lower reproductive output. The research was published in Scientific Reports, and was authored by Katherine Silliman and Tynan Bowyer of the University of Chicago, and SAFS professor Steven Roberts.

Coal mining is well known to have negative impacts on the quality of water in streams, and now new findings show that fish, invertebrates, and salamanders are badly affected by the resulting pollution. A synthesis demonstrated that animal numbers declined by more than half (53%), and species numbers declined by one third, in streams affected by coal mines. These impacts happened in spite of current federal statutes (the 1972 Clean Water Act and 1977 Surface Mining Control and Reclamation Act), and persisted even after cleanup efforts post-mining. More stringent regulations are needed to keep streams clean and healthy in the presence of coal mining. The new research was conducted by Zingli Giam, SAFS professor Julian Olden, and Daniel Simberloff, and is published in the journal Nature Sustainability.

More than 80% of the world’s renewable electricity comes from hydropower generated from dams, but these dams impede upriver passage of fish, and potentially damage fish migrating downstream that pass through turbines or over slipways. A new toolset has now been developed that can better estimate injury and death rates from fish passing downstream, using the data from artificial “sensor fish” that mimic the passage of fish through turbines and slipways while collecting high-resolution data. The new tool allows users to design new studies and analyse the data from sensor fish using statistically rigorous methods, and will help future design and current operation of hydropower dams so that their impacts on fish can be reduced. A paper describing the new tool, by Hongfei Hou and coauthors including SAFS professor John Skalski and SAFS research consultant Richard Townsend, appears in a recent issue of the journal Energies.

The Bering Sea has highly variable sea ice extent in winter, which can be used to tease out the effects of future climate change on marine animals such as seabirds. In a new study, SAFS professor George Hunt and coauthors examined how seabirds change location in years when sea ice melts earlier in the year. In these years, seabirds that feed far from land tend to come closer inshore, while seabirds that feed closer to shore move further offshore. Furthermore, in warm years, small zooplankton experience changes in their growth and reproduction, which brings more young, abundant, pollock into surface waters where they can be eaten by seabirds. In the future holding warmer waters, seabirds may rely more heavily on young pollock, which has less nutritional value than other prey items. The work was published in the journal Marine Ecology Progress Series.

A marine heat wave called The Warm Blob parked itself over the North Pacific Ocean in 2014-15, and has now been determined to be responsible for an unusually large mass mortality of Cassin’s Auklets. Volunteers involved in three citizen science projects (COASST, BeachWatch, BeachCOMBERS) scour beaches from California to British Columbia, and reported thousands of dead Cassin’s Auklets at the same time that the Blob was present. A new collaborative study examined a range of possible hypotheses for the mass death, finding that the best explanation was a shift in the marine food available for the auklets, resulting in death by starvation. The work, by SAFS researchers Timothy Jones, Hillary Burgess and Jane Dolliver, SAFS professor Julia Parrish, and a broad array of coauthors, appears in the journal Geophysical Research Letters.

Science can often benefit from broad participation in data collection by the public. For example, people recording their bird sightings in the eBird app has led to multiple scientific papers. Now a new paper provides valuable advice on how to set up and run such citizen science projects, including how to start a citizen science project, how to better collect data, and how to measure the impact of such projects. The review was coauthored by SAFS professor Julia Parrish and appears in the journal BioScience.

Ecosystem-based fisheries management (EBFM) has become popular in recent years, but there is broad debate about what it means and how to implement it. At its simplest level, EBFM involves improving fisheries management by moving beyond management designed for single species, towards considering interactions that are important for entire ecosystems. Part if the reason this is difficult, says a new paper, is that perceptions of what counts as EBFM differ among stock assessment scientists, conservationists, ecologists, and managers. In addition, key aspects of EBFM, such as considering interactions among species, protecting habitat, reducing bycatch, and using ecosystem models for management, are unlikely to all be implemented in any particular fishery. Instead, it is important to select aspects of EBFM that are tailored to a specific fishery when implementing EBFM. The new research was conducted by four SAFS graduate students (John Trochta, Maite Pons, Merrill Rudd, and Melissa Krigbaum), together with Alexander Tanz (School of Marine and Environmental Affairs) and SAFS professor Ray Hilborn, and appears in the journal PLoS One.

Many species of fish spend some of the time on the ocean bottom, and some of their time far off the bottom, which makes them hard to survey. Acoustic surveys (that bounce sound off fish schools), can estimate the midwater component of so-called “semipelagic” fish, while trawl surveys can measure the portion on the bottom. Now a new method has been developed that combines data from both types of surveys into a single estimate using information about the environment (bottom light, temperature, sand type, and fish size). The new method has been used to assess the status of walleye pollock, which sustains the largest fishery in the United States, and was developed by Stan Kotwicki, Patrick Ressler, and Jim Ianelli at the Alaska Fisheries Science Center, and SAFS Professors André Punt and John Horne, and appears in the journal Canadian Journal of Fisheries and Aquatic Sciences.