PNNL

Abstract

In response to the rapid decline of Pacific lamprey (Entosphenus tridentatus) in the Pacific Northwest, a submersible sled with the ability to electroshock and detect larval lamprey via optical camera was developed to sample deep-water rearing habitats (>1 m). Three test trials, each consisting of 10 juvenile western brook lampreys (Lampetra richardsoni; 70 -150 mm), were conducted in a laboratory setting to determine the effective shocking area and detection efficiency of the device. Juvenile lampreys were allowed to burrow into an 8.9 cm deep sand/gravel mixture prior to the test trials. An electroshock was delivered for 30 s while lamprey response was observed. Voltage at the surface of the sand/gravel mixture averaged 2.3 volts. The detection efficiency ranged from 40 to 70% for the three trials with a mean detection efficiency of 59%. Mean post-shock emergence time was 4.4 s, with a maximum of 13 s. The device detected juvenile lampreys without transporting them to the surface, thereby increasing sampling volume per unit time and reducing the potential for injury caused by handling. No immediate or post testing mortality was observed for 48 h.