Methods for assessment of short-term coral reef fish movements within an acoustic array

Abstract

BackgroundArrays of passive receivers are a widely used tool for tracking the movements of acoustically-tagged fish in marine ecosystems; however, the spatial and temporal heterogeneity of coral reef environments pose challenges for the interpretation of tag detection data. To improve this situation for reef fishes, we introduced a novel response variable method that treats signal detections as proportions (i.e., percent transmissions detected or “detection rates”) and compared this against prior approaches to examine the influence of array and transmitter performance, signal distance and environmental factors on detection rates. We applied this method to tagged snappers and groupers in the Florida reef ecosystem and controlled range-tests on static targets in Bayboro Harbor, Florida, to provide methodological guidance for the planning and evaluation of passive array studies for coral reef fishes.ResultsLogistic regression analysis indicated detection rates were primarily a non-linear function of tag distance from receiver. A ‘model-weighted’ function was developed to incorporate the non-linear relationship between detection rate and distance to provide robust positioning estimates and allow for easy extension to tags with different ping rates.ConclusionsOptimal acoustic array design requires balancing the interplay between receiver spacing, detection rates, and positioning error. Spacing receivers at twice the distance of the modeled 50% detection rate may be appropriate when quantification of overall space use is a priority, and would provide a minimum of 75% detection rate. However, for research where missing detections within the array is unacceptable or time-at-arrival based fine-scale positioning is needed, tighter receiver spacing may be required to maintain signal detection probability near 100%.

Use of an acoustic telemetry array for fine scale fish behaviour assessment of captive Paiche, Arapaima gigas, breeders

“…Technical and miniaturization improvements have permitted the development of ultrasonic telemetry equipment in aquatic environments (Crossin et al., ; Hussey et al., ) or GPS system in aerial or terrestrial studies, which allow a much higher positioning frequency (Abecasis, Bentes, Lino, Santos, & Erzini, ; Bellquist, Lowe, & Caselle, ; Binder, Holbrook, Hayden, & Krueger, ; Binder et al., ; Espinoza, Farrugia, Webber, Smith, & Lowe, ; Espinoza, Heupel, Tobin, & Simpfendorfer, ; Farmer, Ault, Smith, & Franklin, ; Lowe, Topping, Cartamil, & Papastamatiou, ; Martins et al., ; Mason & Lowe, ; Pursche, Suthers, & Taylor, ; Semmens, ; Simpfendorfer, Heupel, & Hueter, ; Topping, Lowe, & Caselle, ; Villegas‐Ríos et al., ).…”

A spatial point process model to estimate individual centres of activity from passive acoustic telemetry data

“…If time series of relevant environmental drivers are available, detection probabilities can be modeled directly as a function of covariates (Farmer et al., ; Huveneers et al., ). However, in many cases, such data are not available for the entire monitoring period or for all potentially important covariates.…”

“…Assuming that detection probability is a linear function of distance under the mean-weighted COA approach can be considered a form of model misspecification when the true relationship is nonlinear (e.g. Farmer et al, 2013;Huveneers et al, 2016). The mean-weighted method also restricts resulting position estimates to the area within the minimum convex polygon of a receiver array's bounds (Simpfendorfer et al, 2002).…”

“…If time series of relevant environmental drivers are available, detection probabilities can be modeled directly as a function of covariates (Farmer et al, 2013;Huveneers et al, 2016) programmed to transmit at an average delay of 2 min, with a random delay of ±1 min (K = 30).…”

“…However, their major disadvantage is that they do not provide a continuous time series of locations; tag transmissions are only recorded when a tagged animal is within the detection range of an acoustic receiver. Even when a transmitter is within range, the probability that transmissions are detected declines with distance from the receiver due to signal attenuation, which can vary with substrate type, receiver placement relative to tidal currents or obstructions, biofouling, acoustic reverberation, and environmental conditions (Farmer, Ault, Smith, & Franklin, ; Huveneers et al., ; Kessel et al., ; Simpfendorfer, Heupel, & Collins, ). Thus, estimates of tagged animals’ space use must be reconstructed from incomplete detection histories, which are biased by both the design of the receiver array and the detection process.…”