Abstract
AbstractConservation efforts are hampered by limited understanding about how different types of instream infrastructure impact migration patterns and fish survival. We used a rapid, fully online IDEA protocol to elicit expert judgments for the passability of seven different in‐stream infrastructures to elver European eels (Anguilla anguilla) in Great Britain. Nine experts provided judgments via our online survey, followed by a second elicitation via email for reflection and adjustment of initial estimates. We found that on average, bridges were judged the most passable (95% passability), followed by fords, nonperched culverts, weirs, sluices, dams, and perched culverts (7%). Results showed a high degree of agreement about how passable bridges and perched culverts are for elver eels, but less certainty about other infrastructure. Thirty‐four distinct factors were identified that experts believed influence infrastructure passability for elver eels, including: the structure itself, hydraulics, elver characteristics, obstructions (e.g., debris accumulation), and vegetation (e.g., to aid climbing). We discuss how our rapid, online‐only variation on the IDEA protocol compares with the more traditional protocol, and how the expert estimates generated in this study can be used in future scenario building and connectivity modeling, with a view to improving conservation to support species persistence.
Highlights
Migratory fish species are an essential part of marine and freshwater ecosystems (Lennox et al, 2019), transporting nutrients and providing food to ecosystems and millions of people worldwide
Expert interpretation of available evidence into advice is important where data are lacking, and in this article, we focus on the role of expert elicitation for improved understanding about the passability of different instream infrastructure by fish species
The aim of our study was to use structured expert elicitation to estimate the probability that elver eels would pass over or through different infrastructure types that are widely distributed along rivers in Great Britain, and across Europe more broadly (Figure 1)
Summary
Migratory fish species are an essential part of marine and freshwater ecosystems (Lennox et al, 2019), transporting nutrients and providing food to ecosystems and millions of people worldwide. Implementation of potential solutions is limited by a lack of spatial data for the locations and characteristics of instream infrastructure (Belletti et al, 2020) and by gaps in knowledge about how different types of structures (e.g., dams, weirs, and culverts) modify freshwater ecosystems and the species that depend on them (Lennox et al, 2019). Expert interpretation of available evidence into advice is important where data (e.g., direct observation of fish behavior or density, or characteristics of infrastructure; see McKay et al, 2017) are lacking, and in this article, we focus on the role of expert elicitation for improved understanding about the passability of different instream infrastructure by fish species
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