Reproductive biology and feeding habits of the prickly dogfish<i>Oxynotus bruniensis</i>

Finucci, Brittany; Bustamante, Carlos; Jones, Emma; Dunn, Matthew R.

doi:10.1111/jfb.13116

Cited by 20 publications

(34 citation statements)

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“…Examinations of the feeding behaviour of Oxynotus centrina suggest that oxynotids are highly specialized preying on chondrichthyan eggs (Finucci, Bustamante, Jones, & Dunn, ; Guallart et al, ), which most likely has led to significant morphological adaptations. Herein, the fossil taxon † Oxynotus crochardi is sister to extant Oxynotus centrina (Figure ) due to distinctive dental features.…”

Section: Discussionmentioning

confidence: 99%

Of teeth and trees: A fossil tip‐dating approach to infer divergence times of extinct and extant squaliform sharks

et al. 2018

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Fossil tip‐dating allows for the inclusion of morphological data in divergence time estimates based on both extant and extinct taxa. Neoselachii have a cartilaginous skeleton, which is less prone to fossilization compared to skeletons of Osteichthyans. Therefore, the majority of the neoselachian fossil record is comprised of single teeth, which fossilize more easily. Neoselachian teeth can be found in large numbers as they are continuously replaced. Tooth morphologies are of major importance on multiple taxonomic levels for identification of shark and ray taxa. Here, we review dental morphological characters of squalomorph sharks and test these for their phylogenetic signal. Subsequently, we combine DNA sequence data (concatenated exon sequences) with dental morphological characters from 85 fossil and extant taxa to simultaneously infer the phylogeny and re‐estimate divergence times using information of 61 fossil tip‐dates as well as eight node age calibrations of squalomorph sharks. Our findings show that the phylogenetic placement of fossil taxa is mostly in accordance with their previous taxonomic allocation. An exception is the phylogenetic placement of the extinct genus †Protospinax, which remains unclear. We conclude that the high number of fossil taxa as well as the comprehensive DNA sequence data for extant taxa may compensate for the limited number of morphological characters identifiable on teeth, serving as a backbone for reliably estimating the phylogeny of both extinct and extant taxa. In general, tip‐dating mostly estimates older node ages compared to previous studies based on calibrated molecular clocks.

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Section: Discussionmentioning

confidence: 99%

Of teeth and trees: A fossil tip‐dating approach to infer divergence times of extinct and extant squaliform sharks

et al. 2018

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“…Chimaera carophila have not been recorded any larger than observed in this study, but unsexed H. homonycteris have been measured up to 110 cm L C by research trawl surveys (maximum length in this study was 99·8 cm L C ). A rarity of reproductive females has been reported for other New Zealand chondrichthyans (Wetherbee, 1996;Finucci et al, 2016b) and in the North Atlantic (Holt et al, 2013;Moura et al, 2014). Chimaerids may segregate by sex and size (Quinn et al, 1980), which may be a trade-off for minimizing intraspecific competition and sexual conflict (Wearmouth & Sims, 2008) and female chimaerids have been found at greater depths than their male counterparts (Holt et al, 2013).…”

Section: B I O L O G I C a L S A M P L I N Gmentioning

confidence: 99%

Some observations on the biology of two rarely seen deep‐sea chimaerids, Chimaera carophila and Hydrolagus homonycteris

Finucci

Stevens

Jones

et al. 2017

Journal of Fish Biology

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Chimaera carophila (n = 45) and Hydrolagus homonycteris (n = 11), two deep-sea chimaerids rarely caught in the waters off New Zealand, were collected from research trawl catches and commercial fishery catches around New Zealand at depths between 400 and 1300 m, between 2014 and 2016. Additional preserved specimens of both species (n = 58) from museum collections were analysed for size, sex and maturity. External assessment of male claspers and a combination of internal assessments of female gonad mass and oviducal gland width, were used to determine maturity. For both species, length at first maturity was 0·70-0·82 of their maximum observed chimaera length (L ), with females maturing at a larger size. Length at maturity for C. carophila (L range: 28·7-103·9 cm) was estimated at 72·5 cm L for males (n = 163) and 82·5 L for females (n = 58). In H. homonycteris, length at maturity (length range: 78·6-99·8 cm L ) was estimated at 79·1 cm L for males (n = 51) and 80·1 cm L for females (n = 17). Ovarian fecundity was up to 31 for C. carophila and sperm storage was confirmed in the oviducal gland of this species. Both species preyed on benthic invertebrates. Some C. carophila and H. homonycteris inhabit depths beyond most current fisheries, but both species appear to be relatively rare and have reproductive parameters characteristic of low productivity, which may make these species vulnerable to population decline if mortality was to increase in the future.

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“…Plunket's shark, Scymnodon plunketi (Waite, 1910), and prickly dogfish, Oxynotus bruniensis (Ogilby, 1893), were close to meeting the criteria for the threatened categories, and were thus listed as NT. Both species have life histories suggestive of low productivity (Finucci, Bustamante, Jones, & Dunn, ; Francis, Jones, Ó Maolagáin, & Lyon, ), as well as high distribution overlap with fishing across much of their range (45–60% and >60% overlap respectively) (Ford et al, , ). Although research trawl survey relative biomass showed no trends in the fisheries management areas where Plunket's shark and prickly dogfish have been caught, monitoring of the species is poor (coefficient of variation CV of biomass estimates ≥40%), and, at least in the case of Plunket's shark, reasons for lack of trends are unknown (Francis, Roberts, & MacGibbon, ).…”

Section: Resultsmentioning

confidence: 99%

The extinction risk of New Zealand chondrichthyans

Finucci

Duffy²,

Francis

et al. 2019

Aquatic Conservation

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1. The national extinction risk of 103 New Zealand chondrichthyans (sharks, rays, and chimaeras),~10% of the global chondrichthyan fauna, was evaluated for the first time using the International Union for Conservation of Nature Red List of Threatened Species Categories and Criteria. Across 32 families, 103 species were assessed.2. New Zealand holds a high degree of species endemism (20%) with deepwater species dominating the fauna (77%). Sharks were the most speciose group with 68 species (66%), followed by 24 rays (23%), and 11 chimaeras (10%).3. Most species were assessed as Least Concern (60%, 62 species) or Data Deficient (32%, 33 species), with four (3.8%) species listed as Near Threatened and four (3.8%) in a threatened category (Vulnerable, Endangered, Critically Endangered).Threatened species are all oceanic pelagic, of which two are only visitors to New Zealand waters, and their status the result of broader regional declines.4. These results are in stark contrast to other recent regional assessments in Europe and the Arabian Sea and adjacent areas, where up to half of species were listed in a threatened category. However, given New Zealand's extensive deepwater fishing effort and rapid collapses of deepwater chondrichthyan fisheries elsewhere, it is possible that New Zealand populations of many deepwater species are the remnants of previously reduced populations that are now at a low, yet stable level.Ongoing species-level catch monitoring will be required to ensure these species do not become threatened. Recommendations for future research and conservation efforts include resolvingtaxonomic uncertainties, understanding habitat use, and increasing regional collaborations to better understand the effects of fishing on wider-ranging species.

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Reproductive biology and feeding habits of the prickly dogfishOxynotus bruniensis

Cited by 20 publications

References 50 publications

Of teeth and trees: A fossil tip‐dating approach to infer divergence times of extinct and extant squaliform sharks

Of teeth and trees: A fossil tip‐dating approach to infer divergence times of extinct and extant squaliform sharks

Some observations on the biology of two rarely seen deep‐sea chimaerids, Chimaera carophila and Hydrolagus homonycteris

The extinction risk of New Zealand chondrichthyans

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