Despite declining population numbers in the south of the country, manta rays are still being landed in Southern Mozambique amidst growing concern for their conservation status globally.
- Female manta ray captured and killed in Guinjata in February with her unborn embryo.
- Guinjata Beach, Inhambane, Mozambique
At 9.30am on Wednesday 27 February 2013, Adam Baugh, a divemaster at Guinjata Bay Dive Centre, was called down to the beach. Several hundred metres from the dive centre, a mature female reef manta ray (Manta alfredi), had been caught in an inshore gillnet and was being dragged onto the beach. Immediately before arriving on scene, a small under-developed foetus was expelled from the adult manta. According to onlookers, “the baby just came out” of the dying female. By the time he arrived Adam reported no movement from either the adult manta or the small foetus.
Due to its large size the fishermen were reluctant to turn the adult individual over to allow Adam to acquire an ID shot of the ventral surface of the animal for Marine Megafauna Foundation scientists. Almost immediately the ray was expertly cut into pieces by over 30 local fishermen and villagers who had arrived on the scene. During this time, Adam was allowed to take a small sample of the ray, from the dorsal fin, which was later handed over to MMF research staff.
Fishermen interviewed on scene told Adam that the manta would provide enough food to feed the whole village’s inhabitants for a week. Ironically, the head section of the manta ray, including the gill rakers (the most valuable part of the manta, in terms of catch resale) was left discarded on the beach.
- What remained on the beach after the processing
- The manta ray was expertly processed by fishermen
Impending CITES convention
Ironically, focal points from around the world, including two scientific representatives from Mozambique, are gathering together at this moment (March 3rd 2013) in Bangkok Thailand to vote for the inclusion of manta rays on Appendix II of the Convention on International Trade in Endangered Species (CITES). This proposal, put forward by the governments of Ecuador, Columbia, and Brazil, aims to increase international protection of the world’s largest ray species (Genus Manta).
Dr. Andrea Marshall, director of the Marine Megafauna Foundation and principal scientist of MMF’s flagship manta ray program, is in Bangkok where she is representing the country of Ecuador as a delegate in their party. Deeply saddened by the loss of a pregnant manta ray at her main study site, Dr. Marshall remains positive. “Manta rays worldwide face significant threats, but there has been tremendous support and momentum for their conservation recently. A CITES listing would be a major step toward our shared goal of global protection.” The Marine Megafauna Foundation, which has been critically involved in international conservation initiatives on this species for the last decade, urge CITES delegates to carefully consider the manta ray proposal and recommend swift implementation of national action plans throughout the respective Range States.
Manta rays, which were only recognized as two distinct species in 2009, were listed as globally threatened species in 2011 for the first time by the IUCN Shark Specialist Group in recognition of the increased threat they face around the world. In 2011 the giant manta ray was also listed on Appendix I & II of the Convention for Migratory Species Act (CMS).
Summary of pertinent information on manta rays in Mozambique
Mozambique, particularly the Inhambane coast from Zavora in the south to the Bazaruto Archipelago in the north, has emerged as one of the most important aggregation areas for manta rays on the planet. The Inhambane Province boasts one of the largest populations of manta rays in the world, with an identified population exceeding 900 individuals and an estimated population size of over 1500 rays (Marshall et al. 2011). This coastline is the most significant aggregation site for Manta birostris in Africa and boasts the second largest identified population of this species in the world (Marshall 2009, Proyecto Mantas Ecuador unpublished data 2012). This small stretch of coastline has been identified as an extremely critical habitat for Manta alfredi as both a mating ground and birthing ground (Marshall and Bennett 2010).
The high frequency of encounters in southern Mozambique has resulted in a bourgeoning dive tourism industry in the region. International tourists from around the world now flock to this coastline specifically to have encounters with these giant rays. Despite this flourishing tourism industry, which promises to be extremely lucrative while also promoting job creation and infrastructure development, manta rays remain an unprotected species in Mozambique. No comprehensive programs exist to manage populations of these rays or their primary habitat. As such, there currently are no legal safeguards to protect this developing industry or the employment it provides. As these rays do not represent a current or a viable fishery nor do any indigenous populations solely rely upon them for resources or income, there are no real reasons to delay in protecting these populations for use in tourism and for general world heritage.
In Mozambique, an estimated 20-50 M. alfredi are taken by subsistence fishermen annually along a ~100 km length of coast from Barra Point to Zavora (<5% of the total coastline and <1/3 of their primary habitat in the south of the country) (Marshall et al. 2011). Rohner et al. (in press) aimed to distinguish true population trends for both Manta species from short-term environmental fluctuations over an eight-year period in Mozambique. The study’s data indicate a pronounced decrease in abundance of the most heavily fished species, with an 87% decline in the sightings of M. alfredi. The model used in this study included various temporal and environmental variables and the observed decline is therefore not likely to be driven by local parameters but is rather indicative of a true population trend due in large part to external anthropogenic pressures.
To prevent an increase in unsustainable fisheries for this species in Mozambique, particularly shifts from subsistence to trade fisheries, it is imperative that manta rays be protected on a national level and remaining populations be managed carefully to ensure their future viability. Until Mozambique both determines the need for and actions national protection for this species, a CITES listing for manta rays will provide the framework for increased protection for remaining populations in the region. A CITES Appendix II listing will require at minimum that exports be derived from sustainably managed fisheries that are not detrimental to the status of the wild populations that they exploit. While some manta rays will most likely still be landed as bycatch or opportunistically for local consumption, unnatural mortality should be greatly reduced.
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