School of Aquatic and Fishery Sciences

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. Instead, managers should seek to incorporate components of ecosystem-based management that are relevant to the fishery at hand. The new paper was written by SAFS graduate students John Trochta, Maite Pons, Merrill Rudd, Melissa Krigbaum, SMEA graduate student Alexander Tanz, and SAFS professor Ray Hilborn, and appears in the journal PLoS One.

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. But, risk of economic losses were uneven, with the fishery targeting the predator much more negatively affected than the fishery targeting the prey species, particularly when predators are at low abundance. The results show a path forward for managing fisheries using an ecosystem approach instead of a single-species approach: adopt strategies that maintain predator and prey stocks at levels where management decisions are robust to uncertainty about the true state of species interactions. The paper was authored by SAFS professor Tim Essington and appears in the journal Proceedings of the National Academy of Sciences with a commentary by the author here and a UW press release here.

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. There is an urgent need to reduce the amount of plastics discarded into the oceans each year, but instead the amounts are projected to increase by an order of magnitude by 2025, with alarming possible effects on coral reefs around the world. The research was conducted by an international team led by Joleah Lamb of Cornell University, including SAFS MS student Evan Fiorenza.

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. Without processors to purchase additional coho harvest, fishers would have limited short-term incentive to harvest coho. These results highlight the importance of considering the unique constraints and opportunities facing multiple stakeholders when weighing future management options. The work was conducted by SAFS PhD student Timothy Walsworth and professors Daniel Schindler and Timothy Essington and appears in the Journal of Applied Ecology.

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. The work by SAFS Prof. Thomas Quinn and his coauthors was published in Environmental Biology of Fishes.

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. Once they are there, they can enhance their chances of finding prey if the look for actively feeding birds and search for prey in the same local places. These two strategies greatly enhance the chance of finding prey that might be here today and gone tomorrow. The new research by SAFS research scientist Charlotte Boyd and SAFS Profs George Hunt and André Punt, and their coauthors, appears in the journal Behavioral Ecology.