Biology, ecology and conservation of the Mobulidae

Abstract

The Mobulidae are zooplanktivorous elasmobranchs comprising two recognized species of manta rays (Manta spp.) and nine recognized species of devil rays (Mobula spp.). They are found circumglobally in tropical, subtropical and temperate coastal waters. Although mobulids have been recorded for over 400 years, critical knowledge gaps still compromise the ability to assess the status of these species. On the basis of a review of 263 publications, a comparative synthesis of the biology and ecology of mobulids was conducted to examine their evolution, taxonomy, distribution, population trends, movements and aggregation, reproduction, growth and longevity, feeding, natural mortality and direct and indirect anthropogenic threats. There has been a marked increase in the number of published studies on mobulids since c. 1990, particularly for the genus Manta, although the genus Mobula remains poorly understood. Mobulid species have many common biological characteristics although their ecologies appear to be species‐specific, and sometimes region‐specific. Movement studies suggest that mobulids are highly mobile and have the potential to rapidly travel large distances. Fishing pressure is the major threat to many mobulid populations, with current levels of exploitation in target fisheries unlikely to be sustainable. Advances in the fields of population genetics, acoustic and satellite tracking, and stable‐isotope and fatty‐acid analyses will provide new insights into the biology and ecology of these species. Future research should focus on the uncertain taxonomy of mobulid species, the degree of overlap between their large‐scale movement and human activities such as fisheries and pollution, and the need for management of inter‐jurisdictional fisheries in developing nations to ensure their long‐term sustainability. Closer collaboration among researchers worldwide is necessary to ensure standardized sampling and modelling methodologies to underpin global population estimates and status.

A dated molecular phylogeny of manta and devil rays (Mobulidae) based on mitogenome and nuclear sequences

“…Recently, conservation concerns have been raised for mobulids, with population declines recorded for several species (Couturier et al, 2012;Dulvy et al, 2008). Eight out of 11 mobulids are now listed as Near Threatened or worse on the International Union of the Conservation of Nature (IUCN) Red List, with the remaining three species listed as Data Deficient (Table 1).…”

“…Mobulids display life history traits that make them vulnerable to overexploitation (Dulvy et al, 2008(Dulvy et al, , 2014Garcia et al, 2008), i.e. matrotrophic reproduction (nourishment of embryos derived from the mother), large size at birth, slow growth, high maximum age (>30 years in M. alfredi, >20 years in M. birostris and >14 years in M. japanica), delayed age of first reproduction (3-10 years in M. alfredi and possibly 5-6 years in M. japanica) and low fecundity (one pup born every 1-3 years) (reviewed by Couturier et al, 2012;Cuevas-Zimbrón et al, 2012).…”

“…Mobula species share a ventral placement of the mouth, and can be distinguished from each other by maximum DW, coloration, skin, presence or absence of a vestigial caudal spine, structure of filter plates (Paig-Tran et al, 2013), and morphometrics of pectoral fins, tails, cephalic lobes and spiracles (Notarbartolo di Sciara, 1987). M. birostris, M. alfredi, M. mobular, M. japanica and M. tarapacana are among the larger rays in the family, with maximum DWs of 700, 500, 520, 370 and 310 cm respectively (Couturier et al, 2012). M. thurstoni has an intermediate maximum DW of 180 cm, and the remaining Mobula species are smaller, with a maximum DW of up to 130 cm (Couturier et al, 2012).…”

“…M. birostris, M. alfredi, M. mobular, M. japanica and M. tarapacana are among the larger rays in the family, with maximum DWs of 700, 500, 520, 370 and 310 cm respectively (Couturier et al, 2012). M. thurstoni has an intermediate maximum DW of 180 cm, and the remaining Mobula species are smaller, with a maximum DW of up to 130 cm (Couturier et al, 2012).…”

Movements of the reef manta ray (Manta alfredi) in the Red Sea using satellite and acoustic telemetry

“…Demand for gill rakers and fin meat drive directed manta ray fisheries throughout much of their range (Alava et al 2002;Dewar 2002;White et al 2006). There are also more cryptic threats to mantas including mooring and fishing line entanglement (Bigelow and Schroeder 1953;Deakos et al 2011), boat strikes (Deakos 2010), and pressure from ecotourism operations (Dewar et al 2008;Couturier et al 2012).…”