Carcharhinus obscurus: Rigby, C.L., Barreto, R., Carlson, J., Fernando, D., Fordham, S., Francis, M.P., Herman, K., Jabado, R.W., Liu, K.M., Marshall, A., Pacoureau, N., Romanov, E., Sherley, R.B. & Winker, H.

2018 ◽  
Author(s):  
Keyword(s):  
Carcharhinus Obscurus

New polymorphic microsatellite loci revealed for the dusky shark Carcharhinus obscurus through Ion Proton double-digest RAD sequencing

2018 ◽  
Vol 45 (6) ◽  
pp. 2759-2763 ◽  
Author(s):  
Simo N. Maduna ◽  
Charné Rossouw ◽  
Ruhan Slabbert ◽  
Sabine P. Wintner ◽  
Charlene da Silva ◽  
...  
Keyword(s):  
Microsatellite Loci ◽  
Rad Sequencing ◽  
Dusky Shark ◽  
Carcharhinus Obscurus ◽  
Ion Proton ◽  
Polymorphic Microsatellite

scholarly journals The fishes of Ascension Island, central Atlantic Ocean – new records and an annotated checklist

2014 ◽  
Vol 97 (4) ◽  
pp. 783-798 ◽  
Author(s):  
Peter Wirtz ◽  
Jane Bingeman ◽  
John Bingeman ◽  
Ronald Fricke ◽  
Timothy J. Hook ◽  
...  
Keyword(s):  
Fish Species ◽  
New Records ◽  
Thunnus Obesus ◽  
Ascension Island ◽  
Manta Birostris ◽  
Carcharhinus Obscurus ◽  
St Helena ◽  
Kajikia Albida ◽  
Annotated Checklist ◽  
Central Atlantic

A checklist of the fishes of Ascension Island is presented. The speciesRhincodon typus,Alopias superciliosus,Isurus oxyrinchus,Carcharhinus obscurus,Galeocerdo cuvier,Sphyrna lewini,Hexanchus griseus,Manta birostris,Gymnothorax vicinus,Hippocampussp.,Epinephelus itajara,Cookeolus japonicus,Apogon pseudomaculatus,Phaeoptyx pigmentaria,Remora albescens,Caranx bartholomaei,Carangoides ruber,Decapterus tabl,Seriola dumerili,Thalassoma sanctaehelenae,Cryptotomussp.,Ruvettus pretiosus,Acanthocybium solandri,Auxis rochei,Auxis thazard,Euthynnus alletteratus,Katsuwonus pelamis,Thunnus alalunga,Thunnus obesus,Xiphias gladius,Istiophorus platypterus,Kajikia albida,Makaira nigricans,Tetrapturus pfluegeri,Hyperoglyphe perciformis,Schedophilussp.,Cantherhines macrocerus,Sphoeroides pachygasterandDiodon eydouxiiare recorded for the first time from Ascension Island. We have recognized two previous records as identification errors and indicate 11 other records as doubtful. Including the 40 new records, we now list 173 fish species from Ascension Island, of which 133 might be considered ‘coastal fish species’. Eleven of these (8.3%) appear to be endemic to the island and a further 16 species (12%) appear to be shared endemics with St Helena Island.

scholarly journals Patterns in abundance and size of sharks in northwestern Australia: cause for optimism

2019 ◽  
Vol 77 (1) ◽  
pp. 72-82
Author(s):  
Matias Braccini ◽  
Brett Molony ◽  
Nick Blay
Keyword(s):  
Life Histories ◽  
Shark Species ◽  
Sandbar Shark ◽  
Carcharhinus Plumbeus ◽  
Study Region ◽  
Scalloped Hammerhead ◽  
Carcharhinus Obscurus ◽  
Northwestern Australia ◽  
Mean Size ◽  
Catch Rates

Abstract Reliable information for population assessments is rare for sharks. We quantified patterns in catch rates and mean size for numerous tropical and subtropical species from 15 years of fishery-independent surveys (2002–2017) in northwestern Australia. This study region represents an area of ~0.8 million km2 which was closed to commercial shark fishing from 1993 or 2005 onward due to the very high State-wide catches of sandbar (Carcharhinus plumbeus) and dusky (Carcharhinus obscurus) sharks. A total of 43 shark and ray species were sampled, with sandbar shark being the most commonly caught species, followed by milk (Rhizoprionodon acutus), spot-tail (Carcharhinus sorrah), tiger (Galeocerdo cuvier), blacktip (Carcharhinus limbatus and Carcharhinus tilstoni), dusky and sliteye (Loxodon macrorhinus) sharks, and scalloped hammerhead (Sphyrna lewini). For sandbar shark, catch rates increased between 2008 and 2017 whereas for other taxa catch rates were mostly stable (albeit fluctuating). Mean size at capture fluctuated across years with no particular trends. Unlike for other parts of the world, catch rates and mean size of northwestern Australian sharks have been stable or increased in recent years. Though most shark species have conservative life histories, when science, management and enforcement work synergistically, sustainable resource use, recovery and conservation outcomes can all be achieved.

Aspects of the reproductive biology of dusky, spinner and sandbar sharks (Family Carcharhinidae) from the Tasman Sea

2016 ◽  
Vol 67 (4) ◽  
pp. 513 ◽  
Author(s):  
Pascal T. Geraghty ◽  
William G. Macbeth ◽  
Jane E. Williamson
Keyword(s):  
Reproductive Biology ◽  
Stock Assessment ◽  
Temporal Distribution ◽  
Population Modelling ◽  
South Wales ◽  
Tasman Sea ◽  
Carcharhinus Obscurus ◽  
Region Length ◽  
Basic Biology ◽  
Stock Depletion

Increased harvest pressure exerted on sharks worldwide has created a necessity for more information concerning the basic biology of targeted species. This study marks the first dedicated assessment of the reproductive biology of Carcharhinus obscurus, C. brevipinna and C. plumbeus in eastern Australian waters, where these species support a demersal longline fishery. We found all three to be late maturing species of low reproductive output, suggestive of an overarching susceptibility to stock depletion in the region. Length- (L50, cm LT) and age-at-maturity (A50, years), for females and males were respectively 281.1 and 15.5, and 271.9 and 14.6 for C. obscurus; 224.9 and 10.1, and 208.9 and 8.5 for C. brevipinna; and, 174.8 and 9.5, and 164.5 and 7.0 for C. plumbeus. Uterine fecundity (i.e. litter size) was observed at 5–12 (=9.6), 5–14 (=10.6) and 3–12 (=7.8) for the same three species respectively, and increased significantly with maternal length in C. brevipinna. Length-at-birth (L0, cm LT) ranged from 92 to 96 for C. obscurus, 79–82 for C. brevipinna and 66–76 for C. plumbeus, and all three species exhibited lengthy gestation periods, overall embryonic sex ratios of 1:1 and synchronous parturition in autumn. However, given limitations with respect to sample size and temporal distribution inherent in this study, the reproductive parameters defined herein are necessarily preliminary. Nevertheless, this research challenges a range of findings emanating from other parts of the world and, in doing so, raises pertinent questions relating to the resilience to targeted fishing activities of these species in New South Wales waters compared to other oceanic regions. Moreover, it reinforces the importance of locally derived demographic parameters for population modelling and stock assessment.

scholarly journals Dusky sharks (Carcharhinus obscurus) undertake large-scale migrations between tropical and temperate ecosystems

2018 ◽  
Vol 75 (9) ◽  
pp. 1525-1533 ◽  
Author(s):  
Matias Braccini ◽  
Simon de Lestang ◽  
Rory McAuley
Keyword(s):  
Large Scale ◽  
Fork Length ◽  
Austral Summer ◽  
Seasonal Migration ◽  
Marine Predator ◽  
Marine Predators ◽  
The North ◽  
Large Scale Network ◽  
Carcharhinus Obscurus ◽  
Scale Network

Understanding the large-scale migrations of marine predators can allow better representation of their population dynamics. The migration biology of dusky sharks (Carcharhinus obscurus), a cosmopolitan large marine predator with very low resilience to fishing, was quantified using a large-scale network of acoustic receivers deployed across Western Australia. Time-series plotting of individual shark detections and modified logistic modelling were used to determine the timing of acoustically tagged sharks’ seasonal migration, the proportion of the population migrating, and the size at which sharks start to migrate. Large (>200 cm fork length) dusky sharks migrated between areas closed (north) and open (south) to commercial shark fishing. There was limited evidence that smaller sharks occurred in the northern study area, whereas several larger individuals of both sexes undertook repeated north–south displacements, moving between disparate ecosystems within the Indian Ocean (21.7°S–35.4°S) and covering round-trip distances of 2000–3000 km per migratory event. For migrating individuals, the probability of occurring in the north was high in the austral winter–spring and low (males) to moderate (females) during the austral summer–autumn.

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