Multi-institutional team evaluates several factors for the success of a species reintroduction

February 14, 2019

Meryl and her collaborators (now co-authors) in 2015. The team met through the Landscape Genetics Distributed Graduate Seminar and have since formed a multi-year, multi-institution collaboration that includes work with local stakeholders, Seattle City Light utility, federal agencies, and graduate students.

Meryl Mims is lead author on a new paper published this week in Ecosphere. She and her colleagues evaluated the potential roles of environmental, demographic, and genetic factors in the success of a species reintroduction. Specifically, they used an individual-based, spatially-explicit computer modeling framework to simulate the reintroduction of bull trout into a river system in eastern Washington State. The research team evaluated where populations of bull trout might persist, their population numbers, and their genetics in the Pend Oreille River. They also looked at how specific traits of bull trout such as the probability of straying to new habitat affected the outcomes, and they examined the effects of dam removals from the river network.

Mill Pond (taken in 2014), located in Sullivan Drainage, part of the study system. It was removed in 2018 as part of efforts to improve the connectivity of streams and rivers in the system.

Boundary Dam, just downstream of the study system. Dam is approx. 340ft (just over 100m) high and generates, on average, 46% of the power produced by Seattle City Light. This photo was also taken in late spring 2014, and the discharge through the dam was approaching 90,000 cubic feet per second (cfs).

They found that the presence or absence of dams had the greatest overall effect on the probability of bull trout to survive following reintroduction. They also found that the landscape and biological factors such as carrying capacity and stray rate had a much greater effect on genetics over the 200-year simulation than the initial genetic characteristics of the population. This project is one of the first to simultaneously look at genetic outcomes and demographic factors on a realistic landscape with a high-powered computer simulation approach. This work also highlights the utility of simulations in evaluating possible outcomes of species reintroductions when empirical experiments are not feasible.

Location (A, B) of Pend Oreille River and tributaries assessed in this study as a spatial network of habitat patches and barriers (C) for which reintroduction of bull trout (Salvelinus confluentus) (D) was simulated. Bull trout illustration by Joseph R. Tomelleri.