Rays in the Shadows: Batoid Diversity, Occurrence, and Conservation Status in Fiji

This study compiled data from various sources, including a literature review, participatory science programs, and environmental DNA to assess the diversity and occurrence of batoids in Fiji’s waters.

A total of 19 batoid species spanning seven families were identified: 19 through the literature, 12 from participatory science programs, and six via eDNA metabarcoding.

Notably, the first photographic evidence of the bentfin devil ray (Mobula thurstoni, Lloyd, 1908) in Fiji is provided.

Geographic distribution patterns revealed spotted eagle rays and maskrays as predominant in the Western Division.

Responses from in-person interviews suggested the presence of sawfishes.

This study emphasized the efficacy of a multifaceted approach to elucidate the diversity and occurrence of this understudied taxon in Fiji.

In total, 68.4% of the documented species face an elevated risk of extinction based on the International Union for the Conservation of Nature Red List criteria.

Caution is advised in interpreting older literature-based records, particularly for the giant guitarfish, giant stingaree, and the absence of sawfish verification.

Nonetheless, this synthesis contributes to establishing a comprehensive baseline for understanding and conserving ray populations in Fiji.

Keywords: elasmobranchs; participatory science; environmental DNA; biodiversity; Oceania; conservation; distribution; endangered species

Rays_in_the_Shadows_Batoid_Diversity_Occurrence_an_compressed Download

Glaus, K.; Gordon, L.; Vierus, T.; Marosi, N.D.; Sykes, H. Rays in the Shadows: Batoid Diversity, Occurrence, and Conservation Status in Fiji. Biology 2024, 13, 73. https:// doi.org/10.3390/biology13020073

Academic Editors: Cristina Porcu and Andrea Bellodi
Received: 21 December 2023
Revised: 19 January 2024
Accepted: 20 January 2024
Published: 26 January 2024

Abstract

Over recent decades, elasmobranchs (sharks, rays, and skates) have been increasingly recognized among the world’s most threatened marine wildlife, leading to heightened scientific attention. However, batoids (rays and skates) are relatively understudied, especially in Large Ocean States of the Pacific.

This synthesis compiles insights on batoid diversity and occurrence in Fiji’s waters by integrating a literature review, participatory science programs such as the Great Fiji Shark Count (GFSC) Initiative, Projects Abroad Fiji (PA), Manta Project Fiji (MPF), and iNaturalist, along with environmental DNA.

Nineteen batoid species from seven families were identified: 19 species from the literature, 12 from participatory science programs, and six from eDNA analysis.

Notably, this study provides the first photographic evidence for the bentfin devil ray (Mobula thurstoni, Lloyd, 1908) in Fiji. GFSC data indicated the highest species diversity in the Western Division, with spotted eagle rays (Aetobatus ocellatus, Kuhl, 1823) and maskrays (Neotrygon sp.) being observed most.

In-person interviews conducted by PA provided information on the occurrence of wedgefishes and potentially sawfishes.

MPF records and iNaturalist uploads were dominated by reef manta rays (M. alfredi, Krefft, 1868), while the pink whipray (Pateobatis fai, Jordan and Seale, 1906) yielded the most DNA sequences.

Overall, 68.4% of the species face an elevated extinction risk based on the International Union for the Conservation of Nature Red List criteria.

Although caution is warranted with older literature-based records for the giant guitarfish (Glaucostegus typus, Anonymous [Bennett], 1830), giant stingaree (Plesiobatis daviesi, Wallace, 1967), and the lack of sawfish verification, this synthesis highlights the effectiveness of a combined methodological approach in establishing a reference point for the diversity and occurrence of this understudied taxon in Fiji.

https://doi.org/10.3390/biology13020073

Throughout the months of April and November every year, you have the opportunity to help celebrate and record Fiji’s amazing coral reef biodiversity, show you care about our world’s delicate coral reef systems, and have fun, by taking part in the FIJI-WIDE SHARK COUNT!

Easy to do, this is suitable for visitors and locals alike, whether you like to fish, snorkel, or SCUBA dive. We hope that tourists, school children, scientists and all people with an interest in the marine environment will take to the reefs with us to search for the Sharks of Fiji!

The Great Fiji Shark Count will be held across Fiji every April and November every year.

You can do a single count, or take part as many times as you like during that month, so that you cover different reefs. All data will be gratefully accepted!

So, see your resort, watersports operator or travel agent, get your Shark identification materials and dive into the beautiful blue waters of Fiji, to be a part of history!