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Background: To tag large marine vertebrates, without the need to catch them, avoiding using barbs for tag retention, and precisely controlling tag location, the remote Tag Attachment Device on a pole (TADpole) was developed. This allows single-pin tags (Finmount, Wildlife Computers) to be attached to the dorsal fins of free-swimming large marine vertebrates. Results: TADpole comprises a pole-mounted holster that carries a tag. It uses compressed air, and a micro-controller, to rapidly insert a stainless-steel pin through a corrodible metal retaining ring in the first tag attachment wing, the animal's dorsal fin, and then a press fit Delrin retaining ring in the tag wing on the other side of the fin. Tagging only occurs when the trailing edge of the dorsal fin touches a trigger bar in the holster, ensuring optimal pin placement. It was developed using fins from cadavers, then trialed on briefly restrained coastal dolphins that could be followed in successive days and weeks, and then on free-swimming animals in the field. The latter showed very short touch/response intervals and highlighted the need for several iterative revisions of the pneumatic system. This resulted in reducing the total time from triggering to tag application to ~ 20 ms. Subsequent efforts expanded the TADpole's applicability to sharks. One free-swimming Atlantic spotted dolphin, two white sharks, and one whale shark were then tagged using the TADpole. Conclusions: Being able to tag free-swimming dolphins and sharks remotely and precisely with satellite-linked telemetry devices may contribute to solving conservation challenges. Sharks were easier to tag than dolphins. Dolphin touch-to-response times were 28 ms or less. Delphinid skin has unique polymodal axon bundles that project into the epidermis, perhaps a factor in their uniquely fast response, which is 10 × faster than humans. Their primary reaction to tagging is to abduct the flippers and roll the fin out of the TADpole holster. This device has the potential to deliver high-quality tag data from large vertebrates with dorsal fins without the stress and logistics associated with catch-and-release, and without the trauma of tags that use barbs for retention. It also collects a dorsal fin biopsy core. [ABSTRACT FROM AUTHOR]

Stranded marine mammals provide valuable insight into population health of free‐ranging conspecifics; however, the likelihood of carcass detection by the public or trained observers is not well known. To better understand carcass detection rates (CDR), we placed twelve decoy dolphin carcasses around Dauphin Island, Alabama, for 2 weeks, one during peak tourist season and one during the off season. Decoys were placed in regions representing different habitat types (marsh or beach) and levels of human use (low or high). Calls from the public were recorded, and trained observers actively searched for decoys via drone and visual observation either by vessel or UTV and walking. There were 2.5 times more public reports during the peak (n = 38) compared to off season (n = 15), with most reports being from the high‐traffic beach site during peak season (n = 27). Trained observers found more decoys (CDR = 0.88) than the public (CDR = 0.58), however, the public found two decoys that observers did not. Drone searches were slightly more successful (CDR = 0.83) than other methods (CDR = 0.79). Our results indicate that a combination of surveillance methods will enhance carcass detection, and our novel methods can be used across habitat types to improve stranding surveillance, better estimate stranding rates, and inform mortality estimates of many species. [ABSTRACT FROM AUTHOR]

Natural climatic changes and human activities affect environmental balance influencing various global ecosystems including the aquatic one. Here the Gangetic ecosystem of India with Dolphin is focused. The Ganges is India's longest river and its lifeline contributing immensely to the country's overall GDP. Again, it is home to many animals including the Dolphin, recognized to be a reliable health indicator with its hydrodynamic body system which works efficiently by the smart natural technique of echolocation and desquamation. However, industrial effluents, agricultural runoffs, discharge of untreated wastewater along with sedimentation produce gross negative effects on the Gangetic environment. These directly pollute the river, disrupt its regular flow, and obstruct the normal activities of the Dolphin, thus destroying its habitat which ultimately reduces the population and affects the river's bio-diversity balance. Country-wide lockdown during the COVID-19 Pandemic temporarily stops all human interventions. The net outcome is the rejuvenation of the water quality confirmed by the reappearance of the Dolphins after several years along its various stretches. So how the identified steps should be practiced to maintain the Gangetic ecosystem, while maintaining the country's economic growth, has been considered as the greatest challenge here.

As fully aquatic mammals, hearing is arguably the most important sensory component of cetaceans. Increasingly, researchers have been harnessing computed tomography (CT) to investigate the details of the inner ear as they can provide clues to the hearing abilities of whales. We use microCT scans of a broad sampling of the ear bones (periotics) of primarily toothed whales (Odontoceti) to investigate the inner ear bony labyrinth shape and reconstruct hearing sensitivities among these cetaceans, including several taxa about which little is currently known. We find support for sensitivity to the lower frequency spectrum in the archaeocete Zygorhiza kochii and an early toothed mysticete cf. Aetiocetus. Oligocene odontocetes (including one from our novel dataset), stem delphinidans, and two additional species of the long-snouted eurhinodelphinids are found to have been able to hear within the narrow-band high-frequency spectrum (NBHF), which is thought to be a specialized form of hearing that evolved convergently multiple different times in extant groups to avoid predation by macroraptorial predators. Our results thus indicate that NBHF evolved as early as the Oligocene and certainly in stem delphinidans by the early Miocene, and thus may be an ancestral characteristic rather than a more recent innovation in select groups., (© 2024 The Author(s). Journal of Anatomy published by John Wiley & Sons Ltd on behalf of Anatomical Society.)

This study investigates the concentrations of persistent organic pollutants (POPs), specifically polychlorinated biphenyls (PCBs) and dichloro-diphenyl-trichloroethane (DDT) and its derivatives, in the blubber of three dolphin species stranded along the Victorian coast (Australia) from 2002 to 2022: Burrunan dolphins (Tursiops australis, n=19), common bottlenose dolphins (T. truncatus, n=6), and short-beaked common dolphins (Delphinus delphis, n=7). ΣDDT concentrations generally exceeded Σ 9 PCBs across most individuals, with Gippsland Lakes (GL) Burrunan dolphins showing the highest ΣDDT concentrations (1400 to 598,000 ng/g lw), including a maximum of 598,000 ng/g lw in one individual-comparable to dolphins in heavily contaminated areas globally. DDE was the most dominant congener, reflecting its persistence. The DDE/ΣDDT ratio (0.46-1) indicates a historical DDT source, with possible remobilization from land-based stores. PCBs were primarily hexachlorinated congeners (PCB-138, PCB-153, and PCB-156), with extreme Σ 9 PCB levels found (up to 837,000 ng/g lw). Port Phillip Bay Burrunan dolphins and common bottlenose dolphins showed a decline in PCB levels over time, while GL Burrunan and short-beaked common dolphins exhibited minimal change. The widespread presence of hexachlorinated congeners suggests ongoing local PCB contamination despite the 1975 ban on PCB imports. This first multi-species POP assessment in the region reveals PCB and DDT levels that exceed health thresholds in 23 of 36 individuals, impacting 89% of critically endangered Burrunan dolphins. Despite limitations of stranded specimens, this study highlights significant, ongoing risks from banned PCBs and DDTs, underscoring the need for continued monitoring., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests:Chantel S Foord reports financial support was provided by Holsworth Wildlife Research Endowment. Chantel S Foord reports administrative support and article publishing charges were provided by RMIT University. If there are other authors, they declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2025. Published by Elsevier Inc.)