Journal article
Short‐ and long‐term diets of the threatened longhorned pygmy devil ray, Mobula eregoodoo determined using stable isotopes
Journal of Fish Biology, Vol.97(2), pp.424-434
08/2020
PMID: 32415778
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Source: InCites
Abstract
Most mobulids are listed as near threatened to endangered. Nonetheless, effective conservation measures are hindered by knowledge gaps in their ecology and behaviour. In particular, few studies have assessed diets and trophic ecologies that could inform methods to avoid fishing mortality. Here, a shortfall in data for the longhorned pygmy devil ray, Mobula eregoodoo was addressed by describing temporal variability in dietary preferences using stable isotope analysis. During summer and autumn in 2017, five bather‐protection gillnets were deployed off eastern Australia (29° S, 153.5° E). From the catches of these gillnets, 35 adult M. eregoodoo had liver, muscle and stomach contents sampled to determine δ13C and δ15N profiles. Analyses revealed that surface zooplankton and zooplanktivorous teleosts were important dietary components across short‐ and long‐term temporal scales. Large quantities of undigested sandy sprat, Hyperlophus vittatus, in the stomachs of some specimens unequivocally confirm feeding on teleosts. A narrow isotopic niche and minimal isotopic overlap with reef manta rays, Mobula alfredi from the same geographic region in eastern Australia implies M. eregoodoo has unique and highly specialised resource use relative to other mobulids in the area. The species is clearly vulnerable to capture during inshore migrations, presumably where they feed on shallow‐water shoaling teleosts. Female M. eregoodoo likely have a low annual reproductive output, so population recoveries from fishing‐induced declines are likely to be slow. Measures to reduce the by catch of M. eregoodoo in local bather‐protection gillnets, and artisanal fisheries more broadly, should be given priority.
Details
- Title
- Short‐ and long‐term diets of the threatened longhorned pygmy devil ray, Mobula eregoodoo determined using stable isotopes
- Creators
- Katherine B Burgess (Author) - The University of QueenslandMatt K Broadhurst (Author) - New South Wales Department of Primary Industries (Coffs Harbour)Vincent Raoult (Author) - University of NewcastleBetty J. L Laglbauer (Author) - University of the AzoresMelinda A Coleman - New South Wales Department of Primary Industries (Coffs Harbour)Michael B Bennett (Author) - The University of Queensland
- Publication Details
- Journal of Fish Biology, Vol.97(2), pp.424-434
- Publisher
- Blackwell Publishing Ltd; Oxford, UK
- Number of pages
- 11
- Grant note
- NSW Department of Primary Industries
- Identifiers
- 991012925005502368
- Academic Unit
- National Marine Science Centre
- Language
- English
- Resource Type
- Journal article