Data from: Evaluation of acoustic telemetry grids for determining aquatic animal movement and survival

1. Acoustic telemetry studies have frequently prioritized linear
configurations of hydrophone receivers, such as perpendicular from
shorelines or across rivers, to detect the presence of tagged aquatic
animals. This approach introduces unknown bias when receivers are
stationed for convenience at geographic bottlenecks (e.g., at the mouth of
an embayment or between islands) as opposed to deployments following a
statistical sampling design. 2. We evaluated two-dimensional acoustic
receiver arrays (grids: receivers spread uniformly across space) as an
alternative approach to provide estimates of survival, movement, and
habitat use. Performance of variably-spaced receiver grids (5–25 km
spacing) was evaluated by simulating (1) animal tracks as correlated
random walks (speed: 0.1–0.9 m/s; turning angle standard deviation: 5–30
degrees); (2) variable tag transmission intervals along each track
(nominal delay: 15–300 seconds); and (3) probability of detection of each
transmission based on logistic detection range curves (midpoint: 200–1500
m). From simulations, we quantified i) time between successive detections
on any receiver (detection time), ii) time between successive detections
on different receivers (transit time), and iii) distance between
successive detections on different receivers (transit distance). 3. In the
most restrictive detection range scenario (200 m), the 95th percentile of
transit time was 3.2 days at 5 km grid spacing, 5.7 days at 7 km, and 15.2
days at 25 km; for the 1500 m detection range scenario, it was 0.1 days at
5 km, 0.5 days at 7 km, and 10.8 days at 25 km. These values represented
upper bounds on the expected maximum time that an animal could go
undetected. Comparison of the simulations with pilot studies on three
fishes (walleye Sander vitreus, common carp Cyprinus carpio, and channel
catfish Ictalurus punctatus) from two independent large lake ecosystems
(lakes Erie and Winnipeg) revealed shorter detection and transit times
than what simulations predicted. 4. By spreading effort uniformly across
space, grids can improve understanding of fish migration over the commonly
employed receiver line approach, but at increased time cost for
maintaining grids.