Single-Stream Recycling Inspires Selective Fish Passage Solutions for the Connectivity Conundrum in Aquatic Ecosystems

Abstract

Barrier removal is a recognized solution for reversing river fragmentation, but restoring connectivity can have consequences for both desirable and undesirable species, resulting in a connectivity conundrum. Selectively passing desirable taxa while restricting the dispersal of undesirable taxa (selective connectivity) would solve many aspects of the connectivity conundrum. Selective connectivity is a technical challenge of sorting an assortment of things. Multiattribute sorting systems exist in other fields, although none have yet been devised for freely moving organisms within a river. We describe an approach to selective fish passage that integrates ecology and biology with engineering designs modeled after material recycling processes that mirror the stages of fish passage: approach, entry, passage, and fate. A key feature of this concept is the integration of multiple sorting processes each targeting a specific attribute. Leveraging concepts from other sectors to improve river ecosystem function may yield fast, reliable solutions to the connectivity conundrum.

The Use of Barriers to Limit the Spread of Aquatic Invasive Animal Species: A Global Review

“…No studies evaluating the use of light to deter AIS also assessed the impact on native species (Ruebush et al, 2012;Stamplecoskie et al, 2012;Miehls et al, 2017). Zielinski et al (2020) recently proposed a fish pass solution incorporating a sorting process to selectively target traits of non-native fish to impede passage, while promoting passage of native species. However, the effectiveness of this design in providing selective passage has not yet been tested.…”

“…The need for barriers to restrict sea lamprey spread creates tension among stakeholders who differentially value sea lamprey control and passage of native and desirable fish (McLaughlin et al, 2013); recently characterized as the "connectivity conundrum" (Zielinski et al, 2020). Many factors must be considered in sea lamprey barrier removal or mitigation decisions (e.g., barrier age, public safety, costs, and ownership) and the process requires consideration of multiple, often conflicting, value sets and objectives (McLaughlin et al, 2013;Jensen and Jones, 2018;Lin and Robinson, 2019).…”

Prioritizing native migratory fish passage restoration while limiting the spread of invasive species: A case study in the Upper Mississippi River

“…Future prioritization work could evaluate these and other alternatives, however, they are unlikely to be completely effective at limiting invasive species passage (Rahel and McLaughlin, 2018). Zielinski et al (2020) suggest an innovative method of selectively passing desirable fish species modeled on singlestream material recycling, where multiple sorting technologies are used to separate fish based on their physical characteristics. While some of these potential solutions are still in testing and development, they could represent future options for selective fish passage within the UMR and other river basins where selective barrier mitigations are needed.…”

“…In many cases, promoting habitat connectivity for native species conflicts with the need to preclude movement and spread of invasive species (Rahel, 2013). In fluvial ecosystems, this "connectivity conundrum" (Zielinski et al, 2020) occurs where dam removal or construction of fish passes facilitates dispersal not only for desirable native species but also invasive species that can cause economic and/or ecological harm within reconnected streams (McLaughlin et al, 2013;Rahel, 2013). To tackle this challenging problem, approaches that identify dam mitigation opportunities favoring native species despite potential or ongoing invasions are needed (Galat and Zweimüller, 2001;Rahel, 2013;Rahel and McLaughlin, 2018).…”

Insights from a novel, user-driven science transfer program for resource management

“…Contentious tradeoffs exist between the costs and benefits of anthropogenic barrier removal in streams. Anthropogenic barriers (e.g., dams and road-stream crossings) often prevent native fishes from accessing critical habitat, but these same barriers provide benefit by blocking invasive species, such as sea lamprey, from colonizing or accessing upstream habitat-the so-called connectivity conundrum (McLaughlin et al 2013;Zielinski et al 2020) that must be accounted for in all decisions for barrier removal. However, predicting the ecological consequences of barrier removals is rife with uncertainties, and stakeholder values extend well beyond concerns with fish passage McLaughlin et al 2013).…”