Data from: Rebuilding the critically endangered Yangtze finless porpoise population: Successful release from an ex situ conservation programme
Data files
May 28, 2025 version files 81.90 MB
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Radio_data.xlsx
11.60 KB
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README.md
2.72 KB
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RPCD_A4_auto_identification.zip
81.84 MB
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RPCD_A4_Cluster_statistics.xls
28.67 KB
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vessel-based_visual.xlsx
10.85 KB
Abstract
Ex situ conservation and population reinforcements or reintroductions are vital strategies for protecting endangered species, yet efforts for cetaceans have been notably limited. Through post-release monitoring based on wearable radio tag and passive acoustic methods, we report the first successful release of a critically endangered small-toothed whale, the Yangtze finless porpoise (Neophocaena asiaeorientalis asiaeorientalis), into the wild. Our monitoring results indicate that, by the third day after release, the two porpoises from the ex-situ population had joined a local individual and gradually integrated into the core distribution area of the local population. Continuous monitoring by the Yangtze Cetacean Protection Network revealed no recorded deaths among the released porpoises. This successful release demonstrates the potential of this approach as a supplementary measure for the restoration of the Yangtze finless porpoise wild population.
https://doi.org/10.5061/dryad.k0p2ngfj5
Description of the data and file structure
The release of the Yangtze finless porpoise is part of a protective research programme and that the survival of the individuals included was ensured. We applied wearable radio tag to track the Yangtze finless porpoise after releasing. When the porpoises surface to breathe, the tag exposed to the air emits electromagnetic waves, which are collected by the base stations, allowing us to obtain spatiotemporal information on the tagged porpoises. Stationary passive acoustic monitoring (PAM) using automatic porpoise indentification device RPCD-A4 was applied to complement monitoring. Vessel-based visual surveys were conducted to monitor the distribution of wild porpoises post-release.
Files and variables
File: Radio_data.xlsx
Description: This file contains signals transmitted back by wearable radio tags on finless porpoises, which are received by base stations. All signal return times and neighboring base station numbers are marked in Sheet 1. The latitude and longitude coordinates of each base station, as well as the frequency and time sequence of receiving radio signals, are provided in Sheet 2
Variables
- time: radio tag signal return times
- tag: identifier of two porpoises
- station: identifier of base stations
- Y: latitude of base stations
- X: longitude of base stations
- detection_frequency: the frequency of receiving radio signals
- timeline: time sequence of receiving radio signals
File: RPCD_A4_Cluster_statistics.xls
Description: This file contains the number of individuals generated by the automatic identification device RPCD-A4 for Yangtze finless porpoises through screening and clustering of click trains.
Variables
- device: identifier of RPCD-A4
- start_time: starting time of clustering signals
- end_time: ending time of clustering signals
- cluster_number: the number of individuals in a porpoise group using algorithm clustering
File: vessel-based_visual.xlsx
Description: This file contains records of the number and distribution information of wild finless porpoises post-release through vessel-based visual surveys.
Variables
- date: date of survey
- group_size: observed population size of finless porpoises
- lat: latitude of encounters
- lon: longitude of encounters
File: RPCD_A4_auto_identification.zip
Description: 1-second finless porpoise sound clips filtered by RPCD-A4 automatically.
Animals and the release site
Two male YFPs (T21M42: 135.0 cm, 42.4 kg; T21M02: 127.0 cm, 33.2 kg), both from the ex-situ population in Tian-e-Zhou, were captured on April 28, 2021. Following health examinations and the implantation of identification chips, they were transferred to the Laowan branch for a two-year acclimatization period. On April 25, 2023, at 10:30 AM (UTC + 8), both porpoises were released into the upstream waters of the Middle branch, near the Laowan branch (Fig. 1). This release site was chosen due to its relatively low levels of human activity and the presence of abundant fish resources. It is not part of the main navigation channel, and during the dry season, it hosts a stable group of over ten local YFPs.
Tracking with wearable radio tags
The released porpoises were tracked using a wearable radio tag system. This system comprises a flexible vest-style miniature radio tag that transmits signals collected by base stations positioned around the release area (Fig. 2). The vest is designed to fit the porpoise's body, securing the tag on the dorsal side to ensure proper attachment for an extended duration. The vest automatically detaches after the tracking period to minimize any long-term impact on the animal. When the porpoises surface to breathe, the tag exposed to the air emits electromagnetic waves, which are collected by the base stations, allowing us to obtain spatiotemporal information on the tagged porpoises. During tracking, the radio tag was programmed to emit signals every 2 seconds for 2 minutes at 5-minute intervals.
Stationary passive acoustic monitoring (PAM) and vessel-based visual surveys
Long-term monitoring was conducted from April 25 to June 2, 2023, using stationary real-time porpoise click detectors (RPCD-A4, Wuhan Pindu Technology Co., China) and two Soundtraps (Ocean Instruments, New Zealand) near the release site (Fig. 1). Visual surveys based on boats were also carried out from April 26 to 30 and May 7 to 8, 2023 (see Supplementary Methods).
Yangtze Cetacean Protection Network collection of deceased porpoises
The Yangtze Cetacean Protection Network (YCPN), managed by the Institute of Hydrobiology, Chinese Academy of Sciences (IHB, CAS), operates with the support of local governments along the Yangtze River. Residents report any sightings of deceased YFPs to the network. The carcasses are collected and scanned to verify whether the identification chips match the released individuals.