DOI: 10.5061/dryad.k0p2ngfj5
title: Data from: Rebuilding the critically endangered Yangtze finless porpoise population: Successful release from an ex situ conservation programme

description: 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.
description: <strong>Animals and the release
 site</strong> Two male YFPs (T21M42: 135.0 cm,
 42.4 kg; T21M02: 127.0 cm, 33.2 kg), both from the
 <em>ex-situ</em> 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. <strong>Tracking with wearable radio tags
 </strong> 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.
 <strong>Stationary </strong><strong>passive
 acoustic monitoring (PAM) and vessel-based visual
 surveys</strong> 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).
 <strong>Yangtze Cetacean Protection Network collection of
 deceased porpoises</strong> 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.
description: # Rebuilding the critically endangered Yangtze finless porpoise
 population: Successful release from an *ex situ* conservation programme
 [https://doi.org/10.5061/dryad.k0p2ngfj5](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.