Video‐Based Electroshocking Platform to Identify Lamprey Ammocoete Habitats: Field Validation and New Discoveries in the Columbia River Basin

Abstract

AbstractA deepwater electroshocking platform (DEP), developed to sample larval lampreys (ammocoetes) and associated habitat in depths up to 15 m, was recently tested in the field. Searches were conducted at a known rearing location (mouth of the Wind River, Washington) and at locations on the Cowlitz River, Washington, where ammocoetes had not previously been found. At the Wind River, video‐imaged ammocoetes ranged from 50 to 150 mm in water depths between 1.5 and 4.5 m, and were more common in sediments containing organic silt. Ammocoetes (n = 137) were detected at 61% (summer) and 50% (winter). Following the field verification, the DEP was used on the lower 11.7 km of the Cowlitz River. Ammocoetes (n = 41) were found at 26% specific search locations. Cowlitz River sediment containing ammocoetes was also dominated by silt with organic material, often downstream of alluvial bars in water depths from 0.8 to 1.7 m. Test results indicated the DEP was successful at detecting ammocoetes with little to no impact in relation to other sampling methods. The DEP can also be used to characterize lamprey ammocoete habitats.Received October 21, 2016; accepted March 17, 2017 Published online May 12, 2017