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Landon Mitchell
Landon Mitchell

MANTA MANTA


Bali has some amazing diving and snorkelling sites waiting for you. From the majestic manta rays at Nusa Penida, to the World War 2 Liberty shipwreck that has become a stunning artificial reef at Tulamben. Or the leisurely dives and macro life at Padang Bai to the drop offs and clear waters of Amed.




MANTA MANTA



We run snorkelling trips to the best snorkel areas in Bali. Namely Nusa Penida & Nusa Lembongan where we have a great chance to see manta rays and some of the most vibrant reefs in Bali. Beautiful reefs at Padang Bai. Or the USAT Liberty World War 2 shipwreck, which is also an outstanding artificial reef at Tulamben.


These islands are just 45 minutes from Sanur on the east coast of Bali by speed boat. Nusa Penida, Nusa Lembongan and Nusa Ceningan deliver some of the most beautiful reefs and the most amazing marine life in Bali and arguably in the world. Here we have a very good chance to see reef manta rays which grow up to 5 meters / 15 feet across and also during the cooler water season you may be lucky enough to see the mola mola / giant sunfish which grow up to 3.3 meters / 11 feet.


Adults of this large species with their large triangular wings (pectoral fins), and projecting horn-like head flaps (cephalic hood) are unlikely to be mistaken for any other species. The skin is smooth; the mouth is terminal (at the front of the head); tail lacks a spine or stinger. The pacific manta is a black-brown color above and white below.


Mantas feed on plankton, including small fishes and squid. They usually have opportunistic remoras attached to their undersides, looking for scraps that result from the feeding of the mantas, and for protection.


Their behavior with divers is unique—they usually let divers approach them, and seem to enjoy the feeling of air bubbles on their bodies. There is disagreement about riding mantas. Some people believe it should be discouraged, whereas others believe that the closeness with the animal may promote the caring and conservation of these animals as perhaps it has in the case of some whales.


The main threat to the giant manta ray is commercial fishing, with the species both targeted and caught as bycatch in a number of global fisheries throughout its range. Manta rays are particularly valued for their gill rakers, which are traded internationally. In 2018, NOAA Fisheries listed the species as threatened under the Endangered Species Act.


Information on the global distribution of giant manta rays and their population sizes is lacking. Regional population sizes are small, ranging from around 100 to 1,500 individuals, and in areas subject to fishing, have significantly declined. Ecuador is thought to be home to the largest population of giant manta ray, with large aggregation sites within the waters of the Machalilla National Park and the Galapagos Marine Reserve. Overall, given their life history traits, particularly their low reproductive output, giant manta ray populations are inherently vulnerable to depletions, with low likelihood of recovery. Additional research is needed to better understand the population structure and global distribution of the giant manta ray.


Manta rays come in two distinct color types: chevron (mostly black back and white belly) and black (almost completely black on both sides). They also have distinct spot patterns on their bellies that can be used to identify individuals. There are two species of manta rays: giant manta rays (Manta birostris) and reef manta rays (Manta alfredi). Giant manta rays are generally larger than reef manta rays, have a caudal thorn, and rough skin appearance. They can also be distinguished from reef manta rays by their coloration.


The giant manta ray is a migratory species and seasonal visitor along productive coastlines with regular upwelling, in oceanic island groups, and near offshore pinnacles and seamounts. The timing of these visits varies by region and seems to correspond with the movement of zooplankton, current circulation and tidal patterns, seasonal upwelling, seawater temperature, and possibly mating behavior.


Giant manta rays also appear to exhibit a high degree of plasticity or variation in terms of their use of depths within their habitat. During feeding, giant manta rays may be found aggregating in shallow waters at depths less than 10 meters. However, tagging studies have also shown that the species conducts dives of up to 200 to 450 meters and is capable of diving to depths exceeding 1,000 meters. This diving behavior may be influenced by season and shifts in prey location associated with the thermocline.


The giant manta ray is found worldwide in tropical, subtropical, and temperate bodies of water and is commonly found offshore, in oceanic waters, and in productive coastal areas. The species has also been observed in estuarine waters, oceanic inlets, and within bays and intercoastal waterways. As such, giant manta rays can be found in cool water, as low as 19C, although temperature preference appears to vary by region. For example, off the U.S. East Coast, giant manta rays are commonly found in waters from 19 to 22C, whereas those off the Yucatan peninsula and Indonesia are commonly found in waters between 25 to 30C.


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. Gestation is thought to last around a year. Although manta rays have been reported to live at least 40 years, not much is known about their growth and development.


The most significant threat to the giant manta ray is overutilization for commercial purposes. Giant manta rays are both targeted and caught as bycatch in a number of global fisheries throughout their range, and are most susceptible to industrial purse-seine and artisanal gillnet fisheries.


Demand for the gills of manta and other mobula rays has risen dramatically in Asian markets. With this expansion of the international gill raker market and increasing demand for manta ray products, estimated harvest of giant manta rays, particularly in many portions of the Indo-Pacific, frequently exceeds numbers of identified individuals in those areas and are accompanied by observed declines in sightings and landings of the species of up to 95 percent.


Under the ESA, NOAA Fisheries is required to develop and implement recovery plans for the conservation and survival of listed species. NOAA Fisheries has developed a recovery outline to serve as an interim guidance document to direct recovery efforts, including recovery planning, for the giant manta ray until a full recovery plan is developed and approved. The recovery outline presents a preliminary strategy for recovery of the species and recommends high priority actions to stabilize and recover the species.


At the 2013 meeting of the Conference of the Parties to the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES), the Parties agreed to include all manta rays (Manta spp.) in Appendix II of CITES, with the listing effective on September 14, 2014. The inclusion of manta rays in CITES Appendix II will help ensure that the international trade in these species is legal and sustainable.


NOAA Fisheries and our partners conduct various research activities on the biology, behavior, and ecology of the giant manta ray. Some of our partners include federal agencies, nonprofits, and international organizations. The results of this research are used to inform management decisions and enhance our understanding of this threatened species.


Scientists are using the most recent technology to track the movements of giant manta rays. Researchers with NOAA Fisheries and the Marine Megafauna Foundation are working together to place satellite tags on manta rays in south Florida. The team has successfully tagged several juvenile manta rays and the tags are programmed to stay on for six months. The tags are very carefully attached by scientists using techniques that are as minimally invasive as possible.


In 2019, a team of scientists completed a 3-day research cruise in the Flower Garden Banks National Marine Sanctuary in the Gulf of Mexico. The team conducted more than 20 dives throughout the sanctuary in an effort to find and tag a giant manta ray. The information provided by this satellite tagging efforts will help us determine the distribution of depth and temperature used by mantas, as well as evaluate residency and movement patterns.


Through our work with our partners, we have supported research to assess giant manta ray survivorship. Scientists are also using a special kind of satellite tag to assess survivorship of giant manta rays after being caught in artisanal gillnet and industrial purse seine fisheries. Results from this research can be used to develop standards for manta ray bycatch reduction and safe release practices, and inform management measures at a national and international level.


Small tissue samples are collected during tagging or capture for genetic analysis. Genetics are useful in understanding population structure, diversity within the population, and genetic exchange between populations. For example, we are collecting genetic samples to help us determine whether there is movement and genetic exchange among giant manta rays along the U.S. east coast and in the Gulf of Mexico. We are also collecting tissue samples from mobula rays incidentally caught by fisheries operating in the Pacific to determine species composition and investigate genetic stock structure. Tissue samples are less than 0.5 oz and collected by scientists and trained fishery observers using non-invasive methods.


Given that fishing mortality is the main threat to the species, NOAA Fisheries is funding studies to explore bycatch mitigation methods to decrease the number of interactions between fishing gear and giant manta rays. One such study is currently testing the efficacy of bycatch sorting grids to quickly and accurately sort and release mobula rays from purse seine vessels operating in the Pacific. Reducing the handling time of manta rays when caught by fishing vessels can help decrease post-release mortality rates. For this study, NOAA is partnering with the International Seafood Sustainability Foundation (ISSF), in collaboration with researchers from the University of California at Santa Cruz, AZTI research institute, industry partner American Tunaboat Association, and U.S. purse seine vessel owners. 041b061a72


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