Coastal movements of a critically endangered wedgefish species and the importance of transboundary conservation
Data files
Apr 29, 2026 version files 2.29 MB
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ALLdata2025_GeneralLocation3.csv
2.29 MB
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README.md
2.57 KB
Abstract
Wedgefishes represent a threatened group of elasmobranchs with limited knowledge on their ecology and habitat use. In order to improve our understanding on their movement ecology, 28 whitespotted wedgefish Rhynchobatus djiddensis were acoustically tracked for up to seven years along a ~900 km stretch of the South African and Mozambican coastline. While detection rates were low, site fidelity was evident (the majority of detections occurred within 50 km of tagging location). However, there was intraspecific variability in the scales of movement, with individuals tagged in the northern extent of the study region displaying restricted movements (< 100 km), while individuals tagged in the southern extent made significant longshore movements (up to ~500 km). Movements lacked seasonal trends in directionality, suggesting they were not migrations, and the drivers of these movements remain unresolved. This study confirmed for the first time that whitespotted wedgefish undertake transboundary movements between South Africa and Mozambique, highlighting the need for international cooperation and the benefit of the transboundary Marine Protected Area in the conservation of this Critically Endangered species.
Dataset DOI: 10.5061/dryad.b5mkkwhtq
Description of the data and file structure
This study was conducted along a ~900-km stretch of the eastern seaboard of southern Africa. Underwater passive acoustic receivers (models 69 kHz VR2W and VR2AR, Innovasea, Halifax, Canada), forming part of South Africa’s collaborative Acoustic Tracking Array Platform (ATAP) monitor this region from Kei Mouth in South Africa to Santa Maria in southern Mozambique. Whitespotted wedgefish were acoustically tagged opportunistically at multiple locations along the coastline between 2016 and 2021. The data represents the acoustic detections from tagged animals on the acoustic receivers.
Files and variables
File: ALLdata2025_GeneralLocation3.csv
Description:
Variables
- FishID: The unique number associated with the acoustic tag implanted in each individual
- Species: The species tagged
- Sex: The sex of the individual tagged
- LengthTL: The total length of the individual tagged in mm
- Location: A general location name of where the individual was tagged
- TagDate: The date the individual was tagged
- ReceiverSerial: The serial number associated with the acoustic receiver the individual was detected on
- Station: The station name associated with the acoustic receiver the individual was detected on
- Lat: The latitude associated with the acoustic receiver the individual was detected on. Has been rounded to a whole degree given the sensitive nature of location data for Critically Endangered species.
- Lon: The longitude associated with the acoustic receiver the individual was detected on. Has been rounded to a whole degree given the sensitive nature of location data for Critically Endangered species.
- DetectDate(UTC): The date the individual was detected (UTC time zone)
- DetectTime(UTC): The time the individual was detected (UTC time zone)
- DataQuality: The level of confidence in an accurate detection (a = high quality, b = medium quality, c = low quality)
- Model: The type of acoustic tag implanted into the individual
- SerialNumber: The serial number of the acoustic tag implanted into the individual
- NominalDelay (s): The delay between successive pings of the acoustic tag implanted into the individual
- TagBatteryLife(d): The battery life of the acoustic tag implanted into the individual (days)
Code/software
Data can be viewed using any .csv reader