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Manta rays (Manta spp.)

Status | Species Description | Habitat | Distribution | Population Trends | Threats | Conservation Efforts | Regulatory Overview | Taxonomy | Key Documents | More Info

Status

ESA Proposed Threatened - M. birostris
CITES Appendix II - Manta spp. throughout their range

Species Description

Weight:
M. birostris: up to 5,300 pounds (2,400 kg)
M. alfredi: up to 3,000 pounds (1,350 kg)
Length:
M. birostris: 25 feet (8 m)
M. alfredi: 15.5 feet (5 m)
Appearance:
large diamond-shaped body with black backs and a mostly white belly, some have species- and individual-specific black markings
Lifespan:
about 40 years; they reach sexual maturity at 10 years
Diet:
plankton
Behavior:
Gestation is thought to last 10-14 months, and they typically give birth to one pup every 2-3 years.

Manta rays are slow-growing, large-bodied migratory animals with small, highly fragmented populations that are sparsely distributed across the tropics of the world. They are characterized by their large diamond-shaped body with elongated wing-like pectoral fins, ventrally placed gill slits, laterally placed eyes, wide terminal mouths, and paired cephalic lobes (making them the only vertebrate animals with 3 paired appendages).

Manta rays have among the lowest "fecundity" of all elasmobranchs (a subclass of cartilaginous fish), typically giving birth to only one pup every two to three years (or longer in some subpopulations) after reaching maturity at 10 years on average. Gestation is thought to last 10 to 14 months.

Habitat

Manta spp. are pelagic planktivores. Manta birostris is thought to be a seasonal visitor along productive coastlines with regular upwelling, in oceanic island groups, and near offshore pinnacles and seamounts. They visit cleaning stations on shallow reefs, are sighted feeding at the surface inshore and offshore, and are also occasionally observed in sandy bottom areas and seagrass beds. Manta alfredi are commonly sighted inshore, but are also observed around offshore coral reefs, rocky reefs and seamounts. This species is often resident in or along productive near-shore environments, such as island groups, atolls, or continental coastlines, and may also be associated with areas or events of high primary productivity (e.g., upwelling).  Manta birostris has longer migration distances and is more solitary than M. alfredi, though they can aggregate to feed or mate. A possible third species (which is still under investigation) exhibits similar habitat preferences to M. alfredi.

Distribution

Manta spp. are global in range, with the two described species overlapping in some locations and not in others. Manta birostris is the more widely distributed, inhabiting tropical, subtropical, and temperate waters, while M. alfredi is found in tropical and subtropical waters.

Population Trends

There are no stock assessments, but regional population sizes are small and, where known, have generally declined except in areas where the species is specifically protected (e.g., Hawaii, Maldives, Yap, Palau).

Threats

The prebranchial appendages (or gill plates), which Manta spp. use to filter planktonic food from the water, are highly valued in international trade for use in traditional medicine. Cartilage and skins are also traded internationally while meat is consumed or used for bait locally. A single mature M. birostris can yield up to 15.5 pounds (7 kg) of dried gills that retail for up to $680 per kilo in China.

Manta rays are caught throughout their global warm water range in the Atlantic, Pacific, and Indian Oceans in commercial and artisanal fisheries. Fishermen targeting manta rays primarily use harpoons and nets, while significant manta bycatch occurs in purse seine, gillnet, and trawl fisheries targeting other species.  Alterations to terrestrial ecosystems have also been shown to affect manta populations. At Palmyra Atoll in the Pacific, a study linked declines in the manta rays' planktonic food source to areas where native trees have been replaced by cultivated palms.

Conservation Efforts

In October 2012, a number of countries agreed to sponsor a proposal to add all manta rays to Appendix II of CITES to provide further protections from the high demand in international trade. The proposal was passed at the CITES meeting in March 2013 and is now effective as of September 14, 2014. Export of their fins requires permits that ensure the products were legally acquired and that the Scientific Authority of the State of export has advised that such export is not detrimental to the survival of the species.

Regulatory Overview

Many range countries prohibit catch and/or trade of mantas.

On  November 10, 2015, NMFS received a petition from Defenders of Wildlife to list the mantas as threatened or endangered under the ESA . On February 23, 2016, we published a notice that listing of the giant manta ray (M. birostris) and reef manta ray (M. alfredi) may be warranted and conducted a status review of these two species. On January 12, 2017, we published a proposed rule to list the giant manta ray as a threatened species under the ESA. We also determined that  the reef manta ray does not warrant listing under the ESA at this time.

Taxonomy

Kingdom: Animalia
Phylum: Chordata
Class: Chondrichthyes
Order: Rajiformes
Family: Mobulidae
Genus: Manta
Species: spp

Manta rays were split into two species in 2009:

This page includes information on all the Manta species.

Key Documents

(All documents are in PDF format.)
  Federal Register Date
12-month Finding and Proposed Rule to list giant manta ray as threatened 82 FR 3694 01/12/2017
Status Review of the giant and reef manta ray n/a 12/2016

90-Day Finding on Petition to List Mantas under the ESA

81 FR 8874 02/23/2016

90-Day Finding on Petition to List Maui and Kona Reef Manta Ray Populations under the ESA

81 FR 41958 06/28/2016
CITES Appendix II Proposal   10/04/2012

More Information

Updated: January 11, 2017