Steep declines in sightings of manta rays and devilrays (Mobulidae) in southern Mozambique
- Published
- Accepted
- Subject Areas
- Conservation Biology, Ecology, Marine Biology
- Keywords
- Extinction, Elasmobranch, GLM, Conservation, Time-series, Gillnet
- Copyright
- © 2017 Rohner et al.
- Licence
- This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, reproduction and adaptation in any medium and for any purpose provided that it is properly attributed. For attribution, the original author(s), title, publication source (PeerJ Preprints) and either DOI or URL of the article must be cited.
- Cite this article
- 2017. Steep declines in sightings of manta rays and devilrays (Mobulidae) in southern Mozambique. PeerJ Preprints 5:e3051v1 https://doi.org/10.7287/peerj.preprints.3051v1
Abstract
Mobulid rays are one of the most vulnerable chondrichthyan groups due to their low population growth rates and high susceptibility to fisheries. While estimates of human-induced mortality are lacking, sighting trend data can provide an index of their status. We recorded underwater sightings data of Mobula alfredi, M. birostris and M. kuhlii over a 14-year period in southern Mozambique. Generalised linear models were used to standardise sightings and adjust for influences other than time. Standardised sightings of the three species, individually, declined by >90%. Declines in sightings were driven primarily by a rapid decrease between 2003–2007, although the declines continued to 2016. While environmental variables did influence sightings, they did not explain this steep decline over time. Increasing mortality from fisheries is likely to have played a significant role in the declining sightings of these vulnerable species.
Author Comment
This preprint is currently in peer-review in Endangered Species Research.
Supplemental Information
Supplementary table 1
Supplementary table 1. Raw data for the sightings GLMs.