Manta rays (Manta spp.)

Manta rays
(Manta spp.)
Photo: NOAA's Flower Garden Banks National Marine Sanctuary

Did You Know?

· Manta rays are the only vertebrate animals with 3 paired appendages.

Status
CITES Appendix II - Proposed throughout its range

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

Manta rays were split into two species in 2009:

Manta alfredi (added in 2009)
Manta birostris

Additionally, a third species in the Caribbean may soon be declared.

This page includes information on all the Manta species.

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. The third species exhibits similar habitat preferences to M. alfredi.

Distribution
Manta spp. are circumglobal in range, with the two described species overlapping in some locations. Manta birostris is the more widely distributed, inhabiting tropical, subtropical, and temperate waters, while M. alfredi is found in tropical and subtropical waters. The third putative species appears to be a regional endemic limited to the Gulf of Mexico, the Caribbean, and along the eastern coast of the United States.

Population Trends
Global population sizes of manta rays are unknown, but some regional subpopulations have been estimated. Subpopulations appear, in most cases, to be small, with fewer than 1,000 individuals. There are no historical baseline data, but scientists have documented recent population declines of 56-86% within about 7 years--well under one generation period (25 years) in fished populations from key range states. In contrast, some subpopulations that are not fished or are within protected areas in the Maldives, Yap, Palau, and Hawaii appear stable.

Threats

targeted fisheries
bycatch

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 manta rays to Appendix II of CITES to provide further protections from the high demand for gill plates in international trade. The proposal will be considered for adoption at the next CITES meeting in March 2013.

The IUCN Red List status assessment for both species is Vulnerable globally. Manta spp. are legally protected in a few countries and in some small Marine Protected Areas, and M. birostris was listed in Appendices I and II of the Convention on the Conservation of Migratory Species of Wild Animals in 2011.

Regulatory Overview
This species is not listed under the Endangered Species Act.

Key Documents
(All documents are in PDF format.)

Title	Federal Register	Date
CITES Appendix II Proposal		10/04/2012

More Information

Updated: February 27, 2013