Integrating Biologging and Behavioral State Modeling to Identify Cryptic Behaviors and Post-capture Recovery Processes: New Insights From a Threatened Marine Apex Predator

Multisensor biologging provides a powerful tool for ecological research, enabling fine-scale observation of animals to directly link physiology and movement to behavior across ecological contexts. However, applied research into behavioral disturbance and recovery following human interventions (e.g., capture and translocation) has mostly relied on coarse location-based tracking or unidimensional approaches (e.g., dive profiles and activity/energetic metrics) that may not resolve behaviors and recovery processes. Biologging can improve insights into both disturbed and natural behavior, which is critical for management and conservation initiatives, although challenges remain in objectively identifying distinct behavioral modes from complex multisensor datasets. Using white sharks (Carcharodon carcharias) released from a non-lethal catch-and-release shark bite mitigation program, we explored how combining multisensor biologging (video, depth, accelerometers, gyroscopes, and magnetometers), track reconstruction and behavioral state modeling using hidden Markov models (HMMs) can improve our understanding of behavioral processes and recovery. Biologging tags were deployed on eight white sharks, recording their continuous behaviors, movements, and environmental context (habitat, interactions with other organisms/objects) for periods of 10–87 h post-release. Dive profiles and tailbeat analysis (as a standard, activity-based method for assessing recovery) indicated an immediate “disturbed” period of offshore movement, displaying rapid tailbeats and an average tailbeat-derived recovery period of 9.7 h, with evidence of smaller individuals having longer recoveries. However, further integrating magnetometer-derived headings, track reconstruction and HMM modeling revealed a cryptic shift to diurnal clockwise-counterclockwise circling behavior, which we argue represents compelling new evidence for hypothesized unihemispheric sleep amongst elasmobranchs. By simultaneously providing critical information toward conservation-focused shark management and understudied aspects of shark behavior, our study highlights how integrating multisensor information through HMMs can improve our understanding of both post-release and natural behavior, especially in species that are difficult to observe directly.

Marine recreational fishing at Phuket, Thailand

Recreational fishing can produce visitor satisfaction and generate revenue at some global resorts. Yet, government officials seem reluctant to promote angling on tourism websites. Perhaps this is due to a weak linkage with ecotourism, a term often used by developing countries for attracting international visitors to nature-based settings. To learn about fishing experiences in Phuket, Thailand, this study analyzed 100 angler reviews posted on TripAdvisor, a popular source of user-generated content. Reviews consisted of positive (n=878) and negative (n=237) comments. Promotion of fishing tourism requires a multibenefit approach, more than simply catching fish. Billfish anglers are a promising target market since these ecotourists practice catch-and-release fishing, thus aligning visitor experiences and sustainability with economics.

Preproteins couple the intrinsic dynamics of SecA to its ATPase cycle to translocate via a catch and release mechanism

Protein machines undergo conformational motions to interact with and manipulate polymeric substrates. The Sec translocase promiscuously recognizes, becomes activated and secretes >500 non-folded preprotein clients across bacterial cytoplasmic membranes. Here, we reveal that the intrinsic dynamics of the translocase ATPase, SecA, and of preproteins combine to achieve translocation. SecA possesses an intrinsically dynamic preprotein clamp attached to an equally dynamic ATPase motor. Alternating motor conformations are finely controlled by the γ-phosphate of ATP, while ADP causes motor stalling, independently of clamp motions. Functional preproteins physically bridge these independent dynamics. Their signal peptide promotes clamp closing; their mature domain overcomes the rate limiting ADP release. While repeated ATP cycles shift the motor between unique states, multiple conformationally frustrated prongs in the clamp repeatedly catch and release trapped preprotein segments until translocation completion. This universal mechanism allows any preprotein to promiscuously recognize the translocase, usurp its intrinsic dynamics and become secreted.

Quantifying biological responses of catch-and-release angling in understudied fish species and practices

Many catch-and-release angling events involve air exposure and exhaustive exercise that elicit a physiological stress response, and depending on a variety of factors, delayed mortality is a possible outcome. There have been ample studies in this area, however, significant gaps exist in the literature for species that are targeted by more specialized anglers, such as freshwater drum (Aplodinotus grunniens). I quantified physiological and reflex responses in freshwater drum following angling, across seasons. Once a fish was on the line, the fight duration and time exposed to air were varied to account for differences in angler skill level (fight time range: 5 s to 2 min; air exposure range: 20 s to 3 min). Location and severity of injury were determined, blood biopsies were taken to quantify physiological stress, and reflex impairment was assessed. Thirtyone percent of fish captured were deeply hooked in the esophagus tissue. Freshwater drum experienced a disruption in homeostasis as blood glucose, plasma cortisol and plasma lactate increased significantly from baseline values following angling. Additionally, seasonal differences were observed for blood glucose and plasma cortisol as higher values were observed in the summer when compared to the spring. The ‘orientation’ reflex was the most frequently impaired (29 % of fish lacked this reflex), but impairment did not differ seasonally. Because freshwater drum have the largest latitudinal range of any North American freshwater fish and are being targeted more frequently by anglers as of late, it is important to fill this knowledge gap regarding their responses to angling events to develop best practices for anglers to promote conservation. The wide distribution of freshwater drum may also make them a candidate model species for addressing the convergence between assessing the impacts of catch-and-release angling and other environmental issues facing freshwater fishes, such as climate change.