Efficiency of Two‐Way Weirs and Prepositioned Electrofishing for Sampling Potamodromous Fish Migrations

Abstract

Potamodromy (i.e., migration entirely in freshwater) is a common life history strategy of North American lotic fishes, and efficient sampling methods for potamodromous fishes are needed to formulate conservation and management decisions. Many potamodromous fishes inhabit medium‐sized rivers and are mobile during spawning migrations, which complicates sampling with conventional gears (e.g., nets and electrofishing). We compared the efficiency of a passive migration technique (resistance board weirs) and an active technique (prepositioned areal electrofishers; [PAEs]) for sampling migrating potamodromous fishes in Valley River, a southern Appalachian Mountain river, from March through July 2006 and 2007. A total of 35 fish species from 10 families were collected, 32 species by PAE and 19 species by weir. Species richness and diversity were higher for PAE catch, and species dominance (i.e., proportion of assemblage composed of the three most abundant species) was higher for weir catch. Prepositioned areal electrofisher catch by number was considerably higher than weir catch, but biomass was lower for PAE catch. Weir catch decreased following the spawning migration, while PAEs continued to collect fish. Sampling bias associated with water velocity was detected for PAEs, but not weirs, and neither gear demonstrated depth bias in wadeable reaches. Mean fish mortality from PAEs was five times greater than that from weirs. Catch efficiency and composition comparisons indicated that weirs were effective at documenting migration chronology, sampling nocturnal migration, and yielding samples unbiased by water velocity or habitat, with low mortality. Prepositioned areal electrofishers are an appropriate sampling technique for seasonal fish occupancy objectives, while weirs are more suitable for quantitatively describing spawning migrations. Our comparative results may guide fisheries scientists in selecting an appropriate sampling gear and regime for research, monitoring, conservation, and management of potamodromous fishes.

Behavior and Reproductive Ecology of the Sicklefin Redhorse: An Imperiled Southern Appalachian Mountain Fish

“…Fish passage designed for the Sicklefin Redhorse would provide benefits to other migratory species in the fish assemblage, but success would depend on a suitable flow management plan (Thiem et al. ; Favrot and Kwak ). Perhaps the quickest, most cost‐effective approach to range expansion is the reintroduction of the Sicklefin Redhorse into suitable periphery streams and watersheds that were occupied historically.…”

“…Two modified two‐way resistance board weirs were installed and monitored in the Valley River from April 15 to June 30, 2006, and from March 20 to June 9, 2007, to describe directional movement of Sicklefin Redhorses associated with spawning migration (Favrot ; Favrot and Kwak ). Weirs were located 11.8 km and 22.4 km upstream from the confluence of the Valley and Hiwassee rivers.…”

Unexpected recent records of twaite shad (Alosa fallax) in two North-eastern Iberian rivers: recolonization or recovery of remnant populations?

“…This technique is best suited to small, wadeable streams, but in medium-sized rivers, physical habitat limitations (i.e. water depth and river width) can hinder effective sampling (Favrot & Kwak, 2016). Surveys were conducted during the period of natural upstream migration of twaite shad (i.e.…”