We ain’t afraid of no ghosts: Tracking habitat interactions and movement dynamics of ghost PIT tags under differing flow conditions in a sand bed river

North American Journal of Fisheries Management
By: , and 

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Abstract

The use of PIT tags has rapidly proliferated since their introduction, and new mobile detection methods have been developed. However, the presence of ghost tags (i.e., PIT tags left in the system after a fish dies) creates uncertainty about the status (live or dead) of tags detected. Herein, we describe our raft-based mobile PIT tag antenna system, which was used to evaluate the movements of “seeded tags” (i.e., PIT tags that we placed in the river as ghost tag analogs) and their interactions with habitat features. We deployed 5,000 seeded tags in the San Juan River, a large sand-bed river in the southwestern USA. Total distances moved by PIT tags ranged from 0.8 to 4,124 m, but 75% of movements were less than 100 m. Flow conditions causing the smallest to largest movements were (1) base flows, (2) spring runoff flows, (3) flash flood flows, and (4) a combination of spring runoff and flash flood flows. Based on Ivlev's electivity index, tags were more likely to be detected in riffles than in runs. These findings will help to classify mobile PIT tag detections as ghost tags or live fish, a critical data gap limiting the accurate estimation of demographic rates, population status metrics, and descriptions of the habitat use of fishes.

Publication type Article
Publication Subtype Journal Article
Title We ain’t afraid of no ghosts: Tracking habitat interactions and movement dynamics of ghost PIT tags under differing flow conditions in a sand bed river
Series title North American Journal of Fisheries Management
DOI 10.1002/nafm.10371
Volume 39
Issue 6
Year Published 2019
Language English
Publisher Wiley
Contributing office(s) Coop Res Unit Seattle
Description 11 p.
First page 1337
Last page 1347
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