AUTHORS: Devon C. Oliver, MNDNR; Charmayne Anderson, MNDNR; Daniel Spence, MNDNR
ABSTRACT: Riverine fish monitoring protocols often focus on sampling main-channel habitats with a limited number of gears (e.g., electrofishing and hoop nets or gill nets and benthic trawls) or, in some cases, a single gear, often electrofishing; there are notable exceptions, like the Long-term Resource Monitoring Program in the Upper Mississippi River. However, some fish species utilize near-shore, off-channel habitats of rivers (e.g., backwaters, partially submerged islands, and side channels) for most of their lives, if not the entirety. Alternatively, for those species that use near-shore, off-channel habitats for a limited part of their life history, sampling these habitats may offer the opportunity to find "the needle in the haystack" before the "haystack" becomes the much larger and deeper main channel of the river, especially in the case of small-bodied species. Nevertheless, gear evaluations and survey designs for sampling these habitats and riverine fish assemblages, in general, have lagged behind those for lentic systems and smaller lotic systems (i.e., streams). This study aimed to compare the efficacy of mini-fyke nets, cylinder minnow traps, shoreline seining, and near-shore backpack electrofishing for sampling fishes in near-shore, off-channel riverine habitats. Sampling was conducted over three weeks in pools 3, 5, and 6 of the Upper Mississippi River; three sites were randomly selected from each pool. Additionally, sampling with each of the four gears was replicated thrice for 108 samples across all sites. Shore seining and cylinder minnow traps were the most likely to produce zero catches. Backpack electrofishing and mini-fyke nets had the most consistent catch rate and highest species richness.
