Spatial ecology and conservation of Manta birostris in the Indo-Pacific

Stewart, Joshua; Beale, Calvin S.; Fernando, Daniel; Sianipar, Abraham B.; Burton, Ronald S.; Semmens, Brice X.; Aburto‐Oropeza, Octavio

doi:10.1016/j.biocon.2016.05.016

Cited by 73 publications

(107 citation statements)

References 48 publications

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“…The individuals sampled in our study spanned a range of disc widths from juveniles to mature adults in all regions and species with the exception of M. thurstoni in Peru. This suggests that both juvenile and adult mobulids may occupy the same habitats and target the same prey, as proposed for M. birostris by Stewart et al (2016a). This is further supported by captures of both mature and juvenile mobulids in the same nets in the Philippines (J. M. Rambahiniarison pers.…”

supporting

confidence: 68%

Trophic overlap in mobulid rays: insights from stable isotope analysis

Stewart¹,

Rohner²,

Araújo³

et al. 2017

Mar. Ecol. Prog. Ser.

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Mobulid rays, a group of closely related filter-feeders, are threatened globally by bycatch and targeted fisheries. Their habitat use and feeding ecology are not well studied, and most efforts have focused on temporally limited stomach content analysis or inferences from tagging data. Previous studies demonstrate a variety of different diving behaviors across species, which researchers have interpreted as evidence of disparate foraging strategies. However, few studies have examined feeding habitats and diets of multiple mobulid species from a single location, and it is unclear if the proposed differences in diving and inferred foraging behavior are examples of variability between species or regional adaptations to food availability. Here, we use stable isotope data from mobulids landed in fisheries to examine the feeding ecology of 5 species at 3 sites in the Indo-Pacific. We use Bayesian mixing models and analyses of isotopic niche areas to demonstrate dietary overlap between sympatric mobulid species at all of our study sites. We show the degree of overlap may be inversely related to productivity, which is contrary to prevailing theories of niche overlap. We use isotope data from 2 tissues to examine diet stability of Manta birostris and Mobula tarapacana in the Philippines. Finally, we observe a significant but weak relationship between body size and isotope values across species. Our findings highlight challenges to bycatch mitigation measures for mobulid species and may explain the multi-species mobulid bycatch that occurs in a variety of fisheries around the world.

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supporting

confidence: 68%

Trophic overlap in mobulid rays: insights from stable isotope analysis

Stewart¹,

Rohner²,

Araújo³

et al. 2017

Mar. Ecol. Prog. Ser.

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“…Recent studies on the movements and population connectivity of M. birostris did not show any long-range migratory movements (Graham et al, 2012;Stewart et al, 2016), but a fine-scale population structure with non-overlapping geographic ranges (Stewart et al, 2016). These findings suggest higher isolation than previously assumed between sub-populations in these different regions, and the possibility of local populations with little exchange among them.…”

Section: Mobulids In the Bohol Seamentioning

confidence: 56%

Life History, Growth, and Reproductive Biology of Four Mobulid Species in the Bohol Sea, Philippines

et al. 2018

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In light of the global decline of mobulid populations and the necessity for sustainable fisheries management, baseline data for population dynamics were collected from a targeted fishery in the Bohol Sea, Philippines. This study focused on life-history parameters and reproductive cycles of four mobulid rays (Mobula thurstoni, Mobula japanica, Mobula tarapacana, and Manta birostris), and re-estimated their intrinsic population growth rates. Size and reproductive data were collected from 1,509 specimens (30% of catch) landed in two fishing seasons in 2015 and 2016. Size-at-birth was reviewed, and analysis of the embryos and follicles did not show any clear seasonality in the reproductive cycle, but supported an interbreeding interval. Females of all species matured at a larger size than males, and exhibited a larger size-at-pregnancy than -at-maturity. This delay in reproduction resulted in population growth rates lower than the actual r max when based on size-at-pregnancy (r mat = r max = 0.016-0.055 year −1 and r preg = 0.008-0.044 year −1 ), and a population doubling time of 15.8-86.6 years. This study suggests that population growth rates previously reported were overestimated. In light of the Convention on International Trades of Endangered Species (CITES) and Convention on Migratory Species (CMS) assessments, while fisheries management should reflect the delayed maturation of these species and the slower population growth potential, at the current status of these population, the sustainability of any exploitation level seems unrealistic and strongly discouraged.

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“…, Stewart et al. ), while chemical tracers like stable isotopes and trace elements can provide a means for determining site fidelities to areas critical to different life‐history stages (juvenile rearing, reproduction, etc. ; Bergstad et al.…”

Section: Applicationsmentioning

confidence: 99%

Acoustic telemetry and fisheries management

Crossin

Heupel

Holbrook

et al. 2017

Ecological Applications

269

196

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This paper reviews the use of acoustic telemetry as a tool for addressing issues in fisheries management, and serves as the lead to the special Feature Issue of Ecological Applications titled Acoustic Telemetry and Fisheries Management. Specifically, we provide an overview of the ways in which acoustic telemetry can be used to inform issues central to the ecology, conservation, and management of exploited and/or imperiled fish species. Despite great strides in this area in recent years, there are comparatively few examples where data have been applied directly to influence fisheries management and policy. We review the literature on this issue, identify the strengths and weaknesses of work done to date, and highlight knowledge gaps and difficulties in applying empirical fish telemetry studies to fisheries policy and practice. We then highlight the key areas of management and policy addressed, as well as the challenges that needed to be overcome to do this. We conclude with a set of recommendations about how researchers can, in consultation with stock assessment scientists and managers, formulate testable scientific questions to address and design future studies to generate data that can be used in a meaningful way by fisheries management and conservation practitioners. We also urge the involvement of relevant stakeholders (managers, fishers, conservation societies, etc.) early on in the process (i.e., in the co-creation of research projects), so that all priority questions and issues can be addressed effectively.

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Spatial ecology and conservation of Manta birostris in the Indo-Pacific

Cited by 73 publications

References 48 publications

Trophic overlap in mobulid rays: insights from stable isotope analysis

Trophic overlap in mobulid rays: insights from stable isotope analysis

Life History, Growth, and Reproductive Biology of Four Mobulid Species in the Bohol Sea, Philippines

Acoustic telemetry and fisheries management

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