Carcharhinid Sharks Research Articles

No apparent negative tagging effects after 13 years at liberty for lemon shark, Negaprion brevirostris implanted with acoustic transmitter.

An intact and uncompromised internal acoustic transmitter was non-lethally recovered from a lemon shark Negaprion brevirostris, after 13 years at liberty. The shark, first tagged at an estimated age of 2 years old near South Bimini, Bahamas in 2004, was recaptured in 2017 with a total length of 264 cm. The tagged shark displayed typical growth rate, pregnancy, natal homing and pupping behaviour of other individuals in this population. This observation provides important evidence regarding the effects from long-term retention of implanted acoustic transmitters in a carcharhinid shark.

First report on a diverse Neogene cartilaginous fish fauna from Borneo (Ambug Hill, Brunei Darussalam)

The highest biodiversity of marine fishes occurs in South-east Asia in the Indo-Australian Archipelago (IAA). However, the fossil record of fishes is very sparse and extremely incomplete in the IAA. Here we present a diverse fossil cartilaginous fish fauna from Borneo, found in late Miocene sediments in Brunei Darussalam. This fauna provides the first insight into the types of fishes that existed in the IAA region about 6.5–8 million years ago. The chondrichthyan remains belong to 24 selachian and batoid taxa. The shark fauna is dominated by Carcharhiniformes, comprising three families with at least 12 taxa, most related to modern species: Hemigaleidae (one species), Carcharhinidae (nine) and Sphyrnidae (two). In addition, the teeth of one Lamniformes shark, the extinct giant macro-predator Otodus (Megaselachus) megalodon, are present in the fauna. The batoids are dominated by Myliobatiformes from the following families: Dasyatidae (three species), Aetobatidae (one), Myliobatidae (three), Rhinopteridae (one), while three taxa of the order Rhinopristiformes were also recovered: Pristidae (one species), and Rhinidae (two). Such diversity of fossil cartilaginous fish has never before been reported from the tropical region of South-east Asia. The dominance of the carcharhinid sharks and small rays suggests a shallow marine, coastal palaeoenvironment. The presence of the freshwater shark genus Glyphis indicates a nearby fluvial influence. Some species of the ray genera, such as Himantura or Pastinachus, have also been reported from estuaries and fresh water. The lack of some generally common Neogene taxa, such as Odontaspididae, Lamnidae and Alopidae, may be linked to such local factors and the coastal shallow-water environment.

New carcharhiniform sharks (Chondrichthyes, Elasmobranchii) from the early to middle Eocene of Seymour Island, Antarctic Peninsula

ABSTRACTSeymour Island, Antarctic Peninsula, is known for its wealth of fossil remains. This island provides one of the richest fossiliferous Paleogene sequences in the world. Chondrichthyans seemingly dominate this Eocene marine fauna and offer a rare insight into high-latitude faunas during the Palaeogene. So far, only a few isolated teeth of carcharhinid sharks have been reported from Seymour Island. Bulk sampling in the well-exposed La Meseta and Submeseta formations yielded new and abundant chondrichthyan material, including numerous teeth of carcharhinid and triakid sharks. Here, we present a reevaluation of the previously described carcharhinid remains and a description of new taxa: Meridiogaleus cristatus, gen. et sp. nov., Kallodentis rythistemma, gen. et sp. nov., Abdounia richteri, sp. nov., and Abdounia mesetae, sp. nov. The carcharhiniforms Mustelus sp. and Galeorhinus sp. are reported based on rare material, whereas teeth previously assigned to Scoliodon represent a nomen dubium.https://zoobank.org/urn:lsid:zoobank.org:pub:6FA3D201-3686-4129-BC09-10FC86E3DD34Citation for this article: Engelbrecht, A., T. Mörs, M. A. Reguero, and J. Kriwet. 2017. New carcharhiniform sharks (Chondrichthyes, Elasmobranchii) from the early to middle Eocene of Seymour Island, Antarctic Peninsula. Journal of Vertebrate Paleontology. DOI: 10.1080/02724634.2017.1371724.

Shark bite injuries on three inshore dolphin species in tropical northwestern Australia

AbstractPredation risk has a profound influence on the behavior of marine mammals, affecting grouping patterns and habitat use. Dolphins frequently bear evidence of shark bites, which can provide an indirect measure of predation pressure. Using photo‐identification data, we investigated the prevalence of shark bites on three sympatric species of inshore dolphin, the Australian snubfin (Orcaella heinsohni), Australian humpback (Sousa sahulensis), and Indo‐Pacific bottlenose dolphin (Tursiops aduncus), among four study sites in northwestern Australia. Bite prevalence varied markedly between species, with 72% of snubfin, 46% of humpback, and 18% of bottlenose dolphins exhibiting evidence of shark bites. Binomial logistic regression confirmed a high likelihood of bite presence on snubfin dolphins, and at one particular site for snubfin and bottlenose dolphins. The prevalence of tiger shark (Galeocerdo cuvier) bites on snubfin dolphins was high, and bites attributed to other carcharhinid sharks were observed on all species. While acknowledging methodological differences with other studies, the prevalence of shark bites on snubfin dolphins is among the highest reported for any dolphins, suggesting predation risk represents an important but varying influence thereon. This study provides a baseline for future investigations into the affect of predation risk on the behavioral ecology of these sympatric species.

Upper Oligocene marine fishes from nearshore deposits of the Central Paratethys (Máriahalom, Hungary)

A rich and diverse ichthyofauna is described from the upper Oligocene (Egerian) sands of Mariahalom, Hungary. The site is dominated by brackish molluscs that are preserved together with rare marine and terrestrial vertebrates. Based on the isolated elasmobranch and bony fish remains, eight sharks, four rays and seven teleost taxa were identified from Mariahalom. The ichthyofauna represents a nearshore marine subtropical community dominated by odontaspidid and carcharhinid sharks and by euryhaline durophagous sparids and by sciaenid teleost fishes. Epibenthic feeders were common, whereas piscivorous taxa included barracudas, billfishes and numerous sharks, including the macropredatory Otodus angustidens. Palaeontological, sedimentological and stratigraphical data indicates a tide-influenced and fluvial-influenced nearshore palaeoenvironment with brackish lagoons and normal marine littoral habitats. The remains of terrestrial, brackish and nearshore marine invertebrates and vertebrates accumulated in a tidal channel. The systematics of the ichthyofauna is consistent with the palaeogeography inferred from invertebrates, i.e. a Central Paratethys connected to the Mediterranean area during the Egerian.

Transcoelomic expulsion of an ingested foreign object by a carcharhinid shark

A wild lemon shark (Negaprion brevirostris) was observed to expel an ingested foreign object through its body wall, over a minimum period of 435 days. We observed this lemon shark at a recreational diving feeding site off the coast of Juno Beach (FL, USA) on 12 occasions between 6 December 2014 and 14 December 2016. At the final observation, following expulsion, we observed this lemon shark with scar tissue and in apparent healthy condition. At minimum, this lemon shark was able to survive for over 1 year under perforation of its stomach lining, coelom and body wall. This account provides further evidence for the resilience and recovery capabilities of elasmobranch fish.

Follicle cell processes: a shark thing?

Follicle cell processes (FCP) are identified in two species of carcharhinid shark (Selachii) but are absent in the little skate Leucoraja erinacea (Batoidea). This suggests that FCPs are either a unique structure that evolved in selachians or were lost by the batoids after their divergence, some 280 mya. The presence of FCPs in the selachians would be consistent with the evolution of large oocytes in this group of animals.

A novel field method to distinguish between cryptic carcharhinid sharks, Australian blacktip shark Carcharhinus tilstoni and common blacktip shark C. limbatus, despite the presence of hybrids.

Multivariate and machine-learning methods were used to develop field identification techniques for two species of cryptic blacktip shark. From 112 specimens, precaudal vertebrae (PCV) counts and molecular analysis identified 95 Australian blacktip sharks Carcharhinus tilstoni and 17 common blacktip sharks Carcharhinus limbatus. Molecular analysis also revealed 27 of the 112 were C. tilstoni × C. limbatus hybrids, of which 23 had C. tilstoni PCV counts and four had C. limbatus PCV counts. In the absence of further information about hybrid phenotypes, hybrids were assigned as either C. limbatus or C. tilstoni based on PCV counts. Discriminant analysis achieved 80% successful identification, but machine-learning models were better, achieving 100% successful identification, using six key measurements (fork length, caudal-fin peduncle height, interdorsal space, second dorsal-fin height, pelvic-fin length and pelvic-fin midpoint to first dorsal-fin insertion). Furthermore, pelvic-fin markings could be used for identification: C. limbatus has a distinct black mark >3% of the total pelvic-fin area, while C. tilstoni has markings with diffuse edges, or has smaller or no markings. Machine learning and pelvic-fin marking identification methods were field tested achieving 87 and 90% successful identification, respectively. With further refinement, the techniques developed here will form an important part of a multi-faceted approach to identification of C. tilstoni and C. limbatus and have a clear management and conservation application to these commercially important sharks. The methods developed here are broadly applicable and can be used to resolve species identities in many fisheries where cryptic species exist.

Movements and mortality of two commercially exploited carcharhinid sharks following longline capture and release off eastern Australia

Movements and mortality of two commercially exploited carcharhinid sharks following longline capture and release off eastern Australia

Variation in blacktip shark movement patterns in a tropical coastal bay

Comparisons between shark nursery populations are limited, however recent work has shown different populations exhibit distinct space use patterns. This study examined the residency and space use of young of the year (YOY) and juvenile Australian blacktip sharks, Carcharhinus tilstoni in a northern Australian nursery using acoustic telemetry. Presence and space use patterns exhibited by C. tilstoni were highly variable among individuals. In contrast to other shark nursery populations, the majority of YOY individuals left the nursery area within three months of release, while most juveniles exhibited long-term residency (6 months - 1 year). In addition, YOY individuals used smaller amounts of space than juveniles. Variable activity space size and location indicated individuals used different areas and often moved into new areas. High individual variation in juvenile populations is atypical for carcharhinid sharks, and contrasts with other nursery species, including the common blacktip shark C. limbatus, which are known to exhibit residency and consistent space use patterns in nursery areas. The unique patterns observed among C. tilstoni may be due to a number of factors, including differences in nursery habitat and population structure, or strategies to improve survival. This study highlights the importance of investigating nursery behaviour across different habitats and populations.

Contributions of allochthonous inputs of food to the diets of benthopelagic fish over the northwest Mediterranean slope (to 2300 m)

The contributions of allochthonous inputs of food (food falls, plastics and other anthropogenic remains) in the diets of large fish (6 teleosteans, 3 sharks) were analyzed for depths between 500 and 2300m in the deep Balearic basin (western Mediterranean). The analyses were based on gut contents. The identification was based on a multi-analytic approach, comprising morphological features (including morphometric analysis) and molecular genetics (DNA barcoding method). Remains of a number of anthropogenic, inorganic materials (microplastic fibres, plastic bags and cartons) appeared regularly in the guts of deep-sea fish (e.g., in Trachyrhynchus scabrus and Mora moro), though always at low occurrence (9.1% of fish at most) and negligible weights (< 2%W of diet). In our sampling, covering an area of ca. 12km2, large food falls contribute only a little to fish diets by weight, W, e.g., in shark diets they represented 4.5%W for Centroscymnus coelolepis and 11%W for Galeus melastomus. However, the importance of food falls (e.g., cetacean blubber and carcharhinid shark remains) was substantial locally (up to 70.8%W of C. coelolepis diet) particularly near canyons. The arrival of livestock remains (beef flesh, goat ribs and vertebrae) was shown by molecular analyses to contributed to deep-sea shark diets (ca. 5.5%W) comparably to natural food falls. These remains, which originate from human activity, may locally alter the food webs of oligotrophic environments like that of the deep Mediterranean. Food falls of both natural and anthropogenic origin were mainly found in fish collected close to canyon axes. The only cetacean fall documented in the deep Balearic Basin was also near a canyon, the carcass of a small (ca. 1.2m) striped dolphin, Stenella coeruleoalba, collected in a haul at 1750m off Barcelona.

Historical occurrence of Carcharhinus spp. in the Sea of Marmara during the 1950s

Our current knowledge on the carcharhinid sharks occurring in Turkey's seas comprises rudimentary data. Recently discovered photographic evidence suggests thatCarcharhinusspp. have been present in the Sea of Marmara since the 1950s. This evidence also extends the known historical distributional range ofCarcharhinusspp. into Marmaric waters, a northern extension of the Mediterranean basin. The results of previous and recent ichthyological inventories of the Sea of Marmara suggest that, currently, no species of the Carcharhinidae family occur in Marmaric waters. Further studies could provide an answer to the question: do any species of the Carcharhinidae family inhabit the Sea of Marmara?

Dietary overlap and partitioning among three sympatric carcharhinid sharks

We used stomach content and stable isotope analyses to compare diet as a proxy for ecological similarity among 3 tropical sharks, Carcharhinus leucas, C. amboinensis and the Endangered Glyphis spp. Our analyses suggested that all 3 predators consumed mainly teleost fishes but also preyed on crustaceans, cephalopods and reptiles. Diets varied spatially and through ontogeny. Some juvenile C. leucas sourced prey from the same food web as juvenile C. amboinensis, although prey sources varied among C. leucas nurseries. Dietary overlap existed between sympatric adult C. leucas and C. amboinensis, and both species occupied higher trophic positions than juvenile conspecifics. Although sample sizes for Glyphis spp. were small, our results suggested previously undescribed dietary partitioning between this genus and the sym- patric C. leucas.

Jumping and Spinning by Carcharhinid Sharks: Another View

Abstract Carcharhinus brevipinna (spinner) and Carcharhinus limbatus (blacktip) sharks make spectacular jumps and spinning leaps out of the water. Some believe these are: jumping responses to rid sharksuckers (Echeneis naucrates) that attach to their bodies, chaffing, shuttling, or heat hunter- cool rest behaviors. Examination of North Carolina shark data suggests that C. brevipinna and C. limbatus in temperate waters of North Carolina sense changes in abrupt ocean water temperatures. Echeneis naucrates is just along for the ride. Why after fourty-six years of longlining only one Echeneis naucrates occurred on C. brevipinna while many occurred on C. limbatus is unknown. Perhaps something in the skin texture, not shape, of C. brevipinna deters Echeneis from attaching.

Population structure, spatial distribution and life‐history traits of blacktip reef sharks Carcharhinus melanopterus

During a survey of the population of blacktip reef shark Carcharhinus melanopterus in Moorea (French Polynesia) between 2007 and 2011, population structural characteristics were estimated from 268 individuals. Total length (LT ) ranged from 48 to 139 cm and 48 to 157 cm for males and females, respectively, demonstrating that the average LT of females was larger than that of males. The C. melanopterus population at Moorea showed an apparent spatial sexual segregation with females preferentially frequenting lagoons and males the fore-reefs. Mean growth rate was c. 6 cm year(-1) . Males reached sexual maturity at 111 cm LT . This study reports on the population characteristics of this widespread carcharhinid shark species and makes comparisons with other locations, confirming high geographic variability in the population structure of the species.

Feeding chronology of six species of carcharhinid sharks in the western North Atlantic Ocean as inferred from longline capture data

Time-at-capture data for 6 species of carcharhinid sharks were collected during 2692 fishery-independent longline sets conducted in the western North Atlantic Ocean from 1995 through 2009. As operations occurred continuously throughout the diel cycle, time-at-capture data were used as a proxy for natural feeding behavior to examine the diel feeding chronology of blacknose Carcharhinus acronotus, spinner C. brevipinna, bull C. leucas, blacktip C. limbatus, sandbar C. plumbeus, and Atlantic sharpnose Rhizoprionodon terraenovae sharks. All 6 species were collected during all hours of the diel cycle; however, application of circular statistics revealed that spinner, bull, blacktip and sandbar sharks increased their feeding activity during nocturnal hours. Atlantic sharpnose and blacknose sharks exhibited no significant directedness in time-of- capture, indicating that these 2 species lack distinct feeding patterns. The species-specific differ- ences in feeding chronologies of the sharks examined demonstrate that broad generalizations concerning the feeding behavior of sharks are not appropriate.

Characterization of 12 polymorphic microsatellite DNA loci in the blue shark, Prionace glauca, isolated by next generation sequencing approach

Genetic markers estimating the genetic diversity and population structure of the blue shark (Prionace glauca, Carcharhinidae) have been limited, although this species is one of the most common fishes caught incidentally in the open ocean. A total of twelve novel microsatellite markers in the blue shark were developed using a next generation sequencing approach. All the microsatellite loci isolated were polymorphic with 2–19 alleles, with the observed and expected heterozygosities of 0.25–0.90 and 0.35–0.92, respectively. Cross-species amplification in three other carcharhinid sharks was successful in ten out of twelve loci. The developed microsatellite markers will be useful to analyze the population genetic structure of the carcharhinid sharks including the blue shark.

New sharks of the genus Abdounia (Carcharhiniformes: Carcharhinidae) from the Upper Eocene of the Trans-Ural Region

Two new species of carcharhinid sharks from the Late Eocene deposits (Tavda Formation) of the southern Trans-Urals, Abdounia vassilyevae sp. nov., previously determined as A. aff. beaugei, and A. lata sp. nov., are described. To date, up to five Priabonian species of Abdounia have been recorded. New finds supplement the data on diversity, evolution, and paleobiogeography of Abdounia.

Live-bearing manta ray: how the embryo acquires oxygen without placenta and umbilical cord

We conducted an ultrasonographic experiment on a pregnant manta ray, Manta alfredi (Chondrichthyes, Batoidea). This study showed how the embryo of the live-bearing elasmobranchs respires in the body of the female. In the embryonic stage, the manta ray embryo takes in uterine fluid by buccal-pumping. After birth, the manta ray shifts its respiratory mode from buccal-pumping to ram-ventilation. The rapid reduction of the spiracle size in the young manta ray may reflect this shift of respiratory mode. Unlike mammals or some carcharhinid sharks that acquire oxygen through a placenta and umbilical cord, the manta ray embryo does not have a direct connection with the mother. Thus, the manta ray embryo obtains oxygen by buccal-pumping of the uterine fluid, in the same way that the embryos of egg-laying species obtain oxygen from the water in the egg case. This finding extends our understanding of the diversity of embryonic respiratory systems in live-bearing vertebrates.

Accuracy of species identification by fisheries observers in a north Australian shark fishery

Despite the importance of observers to collect data for effective fisheries management worldwide, their species-identification abilities are rarely assessed. Misidentifications could compromise observer data particularly in diverse, multi-species fisheries such as those in the tropics where visual identification is challenging. Here, we provide the first estimates of the ability of scientific observers to identify five species of morphologically similar carcharhinid sharks (Carcharhinus leucas, C. amboinensis, C. tilstoni, C. sorrah and C. brevipinna) in a fishery in northern Australia. We compared observer field identifications of sharks with genetic validation (814bp mtDNA NADH dehydrogenase subunit 4) to quantify species identification errors. We used binomial generalised linear models to determine the influences of species, gender, total length, and the observer's experience on identification error. We found that identification error (∼20%) depended predominately on the species in question (highest error for C. tilstoni). Male sharks were misidentified less frequently than females, and error decreased marginally with increasing total length. Surprisingly, we found no statistical evidence that observer experience influenced identification error. Our results provide the first benchmark of identification accuracy of observers for carcharhinid sharks in northern Australia and show that estimates of error in species identifications need to be incorporated into management strategies to ensure successful recovery of the many recently over-fished shark populations.