Whale shark occurrence patterns and Endangered status

Synthesis

The whale shark (*Rhincodon typus*) species/rhincodon-typus is the largest extant fish and was reclassified as Endangered on the IUCN Red List in 2016 status/endangered concepts/iucn-categories after evidence of Indo-Pacific population decline. Occurrence records in OBIS and GBIF cluster at persistent seasonal aggregation sites — Ningaloo Reef, the Mexican Caribbean, Donsol, and the Maldives — driven by predictable food pulses such as coral spawning and copepod blooms range/tropical-ocean. Photo-identification of natural spot patterns by citizen-science networks supplies a substantial fraction of public records concepts/photo-id-networks. The principal mortality drivers are vessel strike at coastal aggregation sites threat/ship-strike and incidental capture in tuna purse-seine fisheries threat/fisheries-bycatch in the equatorial Pacific and Indian oceans.

Threads

1. What are the major recorded aggregation sites for whale sharks?

Whale sharks are recorded year-round across tropical and warm-temperate oceans, with persistent seasonal aggregation sites including Ningaloo Reef on the Australian west coast, Holbox and Isla Mujeres in the Mexican Caribbean, Donsol Bay in the Philippines, and the central atolls of the Maldives. These aggregations correspond to dense, predictable food pulses such as coral spawning events and copepod blooms range/tropical-ocean. Occurrence records in public databases are dominated by photo-identification records contributed by citizen-science networks concepts/photo-id-networks alongside fisheries-observer reports.

Cited: species/rhincodon-typus, range/tropical-ocean, concepts/photo-id-networks

2. What are the primary threats driving the whale shark's endangered listing?

The whale shark was reclassified as Endangered on the IUCN Red List in 2016 status/endangered concepts/iucn-categories after evidence accumulated of population decline across the Indo-Pacific. The principal threats are vessel strike threat/ship-strike at coastal aggregation sites where shipping lanes overlap with surface-feeding sharks, and incidental capture or set-on by tuna purse-seine fisheries threat/fisheries-bycatch in the equatorial Pacific and Indian oceans. Directed fisheries persist in a small number of jurisdictions and contribute additional mortality.

Cited: status/endangered, concepts/iucn-categories, threat/ship-strike, threat/fisheries-bycatch

3. How well-covered is whale shark occurrence in public biodiversity datasets?

Whale shark occurrence is comparatively well-sampled relative to many large pelagic species, in large part because photo-identification of natural spot patterns concepts/photo-id-networks allows individual re-sights by tourist operators and researchers to be aggregated into long-term catalogs. Occurrence records in OBIS and GBIF are concentrated at the known aggregation sites listed above; pelagic phases of the life cycle remain undersampled, and depth-resolved telemetry coverage is sparse outside research programs.

Cited: concepts/photo-id-networks, concepts/obis-core, concepts/gbif