Sampling Methods and Survey Designs for Larval Lampreys

Abstract

Knowledge of the biology, distribution, and abundance of lampreys (Petromyzontiformes) is critical to inform conservation actions for native species and to inform control measures for the invasive Sea Lamprey Petromyzon marinus of the Laurentian Great Lakes. Lampreys have complex life cycles that include a freshwater larval stage in which they burrow into substrates consisting of fine sediment and organic matter. The larval stage is frequently targeted in research and monitoring; given this interest, a review of survey designs and methods is needed. Our review identified 12 different sampling methods for larval lampreys and focused on one common method-backpack electrofishing in wadeable habitats. Our review also identified eight research and monitoring questions that have been addressed for larval lampreys in field studies, including distribution, species identification, life stage occurrence, abundance, length frequency, habitat use, residence and movement phenology, and species status. Each question provides unique information and poses distinct challenges to data acquisition and interpretation. The objectives guide decisions about study design and scope of inference. The scope of inference is determined by the size, spatial distribution,

Salvage using electrofishing methods caused minimal mortality of burrowed and emerged larval lampreys in dewatered habitats

“…Methods to salvage larval lampreys exposed to human‐induced dewatering events have been developed (Lamprey Technical Workgroup 2020). In wadable freshwater habitats, larval lampreys of multiple species are commonly collected using backpack electrofishing (Harvey and Cowx 2003; Moser et al 2007; Clemens et al 2022), and the Lamprey Technical Workgroup has defined best management guidelines for using backpack electrofishing for the purposes of salvaging larval lampreys during either watered or dewatered conditions (Lamprey Technical Workgroup 2020). Electrofishing conducted to salvage larval lampreys when their habitat is dewatered is called “dry shocking” (Lamprey Technical Workgroup 2020).…”

Broad‐scale eDNA sampling for describing aquatic species distributions in running waters: Pacific lamprey Entosphenus tridentatus in the upper Snake River, USA

“…We acknowledge that eDNA sampling has weaknesses that are widely recognized, including for sampling Pacific lamprey (Clemens et al ., 2022). Environmental DNA transport in larger river systems tends to promote detections well downstream of individuals releasing DNA (Pont et al ., 2018; Robinson et al ., 2019), so the downstream terminus of habitat occupancy, if present, is uncertain.…”

“…Riaz et al ., 2020). The spatial domain was systematically sampled to ensure even coverage of all potential habitat and to maximize our scope of inference (Clemens et al ., 2022). The majority of samples were collected in a relatively brief period by a small group of biologists and citizen scientists, yet resolved the distribution of a single species across over 10,615 km of potential habitat (itself derived from a 56,168 km stream network).…”

“…A consequence is that broad‐scale surveys often rely on single samples from readily accessible points on a subsample of potentially occupied streams at the expense of more comprehensive inventories throughout a species' range (Kadmon et al ., 2004). That many forms of conventional sampling require permits from regulatory agencies and biologists with extensive experience and specialized skills can further limit the extent and timeliness of species distribution sampling (Clemens et al ., 2022). An additional complication is that an actively managed species of conservation concern may be declining in some areas and expanding in others.…”

Lampreys in California (Lampetra spp. and Entosphenus spp.): Mitochondrial phylogenetic analysis reveals previously unrecognized lamprey diversity

“…Notably, results indicated that multiple species frequently co-occur within basins (HUC6), so accurate species identification will be especially important in efforts to characterize the abundance and distribution of lampreys. Since lampreys are most frequently sampled in the field during the larval phase, when they may lack distinguishing morphological features, genetic species identification would improve the accuracy of data collected and would help to advance our understanding of species distributions (Docker et al 2016;Clemens et al 2022). The genetic marker used for DNA barcoding in this study (cyt b) could not distinguish between all nominal lamprey species in California, but molecular identification of different lamprey species (or ecotypes) is likely feasible with higher resolution genomic sequencing techniques.…”