Fine-scale movement patterns and behavioral states of gray triggerfish Balistes capriscus determined from acoustic telemetry and hidden Markov models

Abstract

Movement is a central feature of the ecology of fish, yet the study of fish movement has been inhibited due to its multidimensional nature and technological and analytical limitations. We used a relatively new fine-scale acoustic tracking system to quantify movements of an economically valuable, demersal marine fish species (gray triggerfish Balistes capriscus) on a natural hardbottom reef on the continental shelf of North Carolina, USA. Overall, 30 fish were tagged and released, and 104,170 highly precise (~ 1-3 m) spatial positions were estimated during the 43-d study. To quantify gray triggerfish movements, we used a combination of exploratory data analyses and hidden Markov models (HMM), the latter of which can identify and elucidate normally hidden behavioral states. Both methods suggested gray triggerfish movements varied by diel period and among individuals, and that some of the variation among individuals could be explained by fish size. Depending on model specification, HMMs identified two or three behavioral states, one of which was likely resting that occurred mostly at night and another was likely foraging or transit that occurred mostly during the day. Moreover, resting at night occurred in small, discrete patches within the study area, whereas foraging or transit behaviors occurred broadly throughout the study area. We encourage a wider use of acoustic telemetry and HMMs to shed light on the normally hidden behaviors of demersal fishes.

Assigning Fates in Telemetry Studies Using Hidden Markov Models: an Application to Deepwater Groupers Released with Descender Devices

“…Typical HMMs for animal movement result in biological descriptions of the behavioral states identified, such as "foraging" or "transiting" (e.g., Bacheler et al 2019). For our purposes, such descriptions were a dubious exercise given the data streams we had available.…”

“…External tagging with acoustic transmitters has increased in popularity due to increased detection ranges (Dance et al 2016) and, for survival studies, the desire to separate the effects of barotrauma from the possible relief caused by tagging (Johnson et al 2015). Attachment methods include the dart tag style used here and by Runde and Buckel (2018), a method by which the transmitter is glued to a T‐bar tag (Yergey et al 2012), procedures involving “cinch‐up” tags (Curtis et al 2015), methods using suture material passed through the fish (Bacheler et al 2019), and attachment via an intramuscular stainless‐steel bolt (Bohaboy et al 2020). To our knowledge, no attempts have been made to quantify tag loss in situ for any of these methods, although some authors used tank holding studies to this end (e.g., Bacheler et al 2019).…”

“…Attachment methods include the dart tag style used here and by Runde and Buckel (2018), a method by which the transmitter is glued to a T‐bar tag (Yergey et al 2012), procedures involving “cinch‐up” tags (Curtis et al 2015), methods using suture material passed through the fish (Bacheler et al 2019), and attachment via an intramuscular stainless‐steel bolt (Bohaboy et al 2020). To our knowledge, no attempts have been made to quantify tag loss in situ for any of these methods, although some authors used tank holding studies to this end (e.g., Bacheler et al 2019). Therefore, the best tag attachment procedure for such studies has not been resolved.…”

“…To date, the utility of HMMs in ecology has been primarily to expand biological knowledge via descriptive studies, although authors have also used HMMs for other purposes (e.g., McClintock et al 2020). In marine fisheries, HMMs have been applied in studies of spawning behaviors (Holan et al 2009), behavior in sharks (Papastamatiou et al 2018), migratory phases of Southern Bluefin Tuna Thunnus maccoyii (Patterson et al 2009) and Cownose Ray Rhinoptera bonasus (Ogburn et al 2018), movement types in Gray Triggerfish Balistes capriscus (Bacheler et al 2019), and behavioral states in Yellowfin Tuna T. albacares and Bigeye Tuna T. obesus (Vermard et al 2010). However, instead of identifying and classifying behaviors of the tagged animals, it is possible that HMMs could identify changes in movement patterns of the tags, which may in fact relate to different animals (e.g., a predator that has ingested a tag).…”

Effects of a seismic survey on movement of free-ranging Atlantic cod

“…on the presence/absence and the detailed, behavioral patterns in spatial use and accelerometer-based activity of cod using hidden Markov models (HMMs), [15][16][17][18] and used linear mixed models for the dose-response analysis.…”