Carcharhinus Brevipinna Research Articles

Relative abundance and size of coastal sharks derived from commercial shark longline catch and effort data

In the north-west Atlantic Ocean, stock assessments conducted for some commercially harvested coastal sharks indicate declines from 64 to 80% with respect to virgin population levels. While the status of commercially important species is available, abundance trend information for other coastal shark species in the north-west Atlantic Ocean are unavailable. Using a generalized linear modelling (GLM) approach, a relative abundance index was derived from 1994 to 2009 using observer data collected in a commercial bottom longline fishery. Trends in abundance and average size were estimated for bull shark Carcharhinus leucas, spinner shark Carcharhinus brevipinna, tiger shark Galeocerdo cuvier and lemon shark Negaprion brevirostris. Increases in relative abundance for all shark species ranged from 14% for C. brevipinna, 12% for C. leucas, 6% for N. brevirostris and 3% for G. cuvier. There was no significant change in the size at capture over the time period considered for all species. While the status of shark populations should not be based exclusively on abundance trend information, but ultimately on stock assessment models, results from this study provide some cause for optimism on the status of these coastal shark species.

Liver lipids of Indian and Atlantic Ocean spinner Carcharhinus brevipinna and blacktip Carcharhinus limbatus sharks

Shark liver oils are rich in polyunsaturated fatty acids, especially the n3 moieties. Data on the liver fatty acids of sharks from African waters, however, are limited. Liver samples from sharks from the western Indian Ocean off the east coast of South Africa and those from the Atlantic Ocean and Gulf of Mexico were examined. This study reports on the fatty acids found in the total lipid fractions from the livers of two shark species found in these regions, the spinner Carcharhinus brevipinna and blacktip Carcharhinus limbatus. Greater amounts of total lipids were found in sharks from the Indian Ocean than in those from the Atlantic Ocean (spinner 0.431 g g−1 vs 0.324 g g−1, p = 0.004; blacktip 0.426 g g−1 vs 0.261 g g−1, p = 0.004). The individual fatty acids in the same animals showed reduced amounts of saturates (spinner 26.22% vs 30.68%, p = 0.013; blacktip 28.94% vs 35.14%, p = 0.007) and slightly increased n3 polyunsaturates (spinner 33.67% vs 22.89%, p = 0.001; blacktip 24.77% vs 18.68%, p = 0.025). Generally, the geographical location rather than the shark species was most important in determining the proportions of hepatic lipids.

Applying genetic techniques to study remote shark fisheries in northeastern Madagascar

Background and aims. The shark fisheries of Madagascar remain largely unstudied. Remoteness makes fisheries monitoring challenging while the high value of shark fins combined with the extreme poverty in Madagascar creates intensive pressure on shark resources.Materials and methods. We use DNA barcoding and species-specific PCR assays to characterize shark fisheries in Antongil Bay in northeastern Madagascar.Results. The 239 samples taken from individuals collected in 2001 and 2002 correspond to 19 species. The four most common species were Sphyrna lewini, Rhizoprionodon acutus, Carcharhinus brevipinna, and C. sorrah. Antongil Bay may be a breeding area for C. brevipinna, C. leucas, and S. lewini.Conclusion. Local names are generally not a useful proxy for monitoring the species harvested in the fishery. Conservation efforts should characterize species exploitation at present, create spatial and temporal fishing restrictions to protect endangered species, and restrict large mesh gillnets.

Fine-scale spatial and seasonal partitioning among large sharks and other elasmobranchs in south-eastern Queensland, Australia

Our understanding of the ecological role of larger elasmobranchs is limited by a lack of information on their spatial and seasonal abundance. Analysis of 14 years of gill-net catch data in south-eastern Queensland, Australia, revealed that the species composition of large sharks and other elasmobranchs significantly differed among beaches and seasons. Spinner sharks (Carcharhinus brevipinna) and hammerhead sharks (Sphyrna spp.) comprised nearly half the catch of all elasmobranchs. Although the distribution of these sharks overlapped, spatial variation existed in their abundance. Spinner sharks characterised the catch at Sunshine Coast beaches, whereas the catch at Gold Coast beaches was dominated by hammerhead sharks. Seasonal differences in elasmobranch community structure were also apparent, driven largely by a lower abundance of many species during the winter and the predominance of species such as spinner sharks and hammerheads in spring and summer. The present study provides the first quantitative data for numerous species of Carcharhiniformes in south-eastern Queensland and demonstrates that analysis of catch-rate data can improve our understanding of how larger sharks partition resources.

Characteristics of the Biology and Distribution of the Spinner Shark (Carcharhinus brevipinna) in Queensland, Australia Based on Data Collected from the Shark Control Program

Characteristics of the Biology and Distribution of the Spinner Shark (Carcharhinus brevipinna) in Queensland, Australia Based on Data Collected from the Shark Control Program

Influence of the annual sardine run on catches of large sharks in the protective gillnets off KwaZulu-Natal, South Africa, and the occurrence of sardine in shark diet

Shark catches in the protective nets set off the beaches of KwaZulu-Natal (KZN), South Africa, are strongly influenced by the sardine run, the winter influx of shoals of Sardinops sagax from the south-west. The effect of the sardine run, which is highly variable from year to year, is greatest in June and July at beaches south of Durban. Total annual shark catch and effort are presented for the period 1952–2005, and total monthly shark catch on the KZN south coast for the period May–August, 1965–2005. Measures to reduce catches of sharks associated with the sardine run have been introduced and have been increasingly successful. Reliable species-specific catch data are available for the period 1978–2005 only. For this period, the spatio-temporal distribution of each of 14 species of shark and the frequency of occurrence of sardine in their diets is documented. Occurrence varies according to species, as does the apparent influence of the sardine run on shark distribution. During June and July on the KZN south coast, sardine were found in the diet of all but two species and frequency of occurrence was 40% or greater in eight species. The presence of copper or bronze whaler sharks Carcharhinus brachyurus in KZN waters appears to be strongly associated with the sardine run, as does that of certain life-history stages of dusky sharks C. obscurus. Spinner sharks C. brevipinna and smooth hammerhead sharks Sphyrna lewini are caught in greater numbers in summer than in winter, but appear to shift their spatial distribution seasonally to feed on sardine.

Identification and evaluation of shark bycatch in Georgia’s commercial shrimp trawl fishery with implications for management

Abstract Many US states have recreational and commercial fisheries that occur in nursery areas occupied by subadult sharks and can potentially affect their survival. Georgia is one of few US states without a directed commercial shark fishery, but the state has a large, nearshore penaeid shrimp trawl fishery in which small sharks occur as bycatch. During our 1995–1998 investigation of bycatch in fishery-dependent sampling events, 34% of 127 trawls contained sharks. This bycatch totalled 217 individuals from six species, with Atlantic sharpnose shark, Rhizoprionodon terraenovae (Richardson), the most common and finetooth shark, Carcharhinus isodon (Muller & Henle) and spinner shark, Carcharhinus brevipinna (Muller & Henle), the least common. The highest catch rates for sharks occurred during June and July and coincided with the peak months of the pupping season for many species. Trawl tow speed and tow time did not significantly influence catch rates for shark species. Gear configurations [net type, turtle excluder device (TED), bycatch reduction device] affected catch rates for shark species. Results of this study indicate gear restrictions, a delayed season opening, or reduced bar spacing on TEDs may reduce shark bycatch in this fishery.

A comparison of the heart and muscle total lipid and fatty acid profiles of nine large shark species from the east coast of South Africa

We have assessed the fatty acid profiles of the hearts and different muscle tissues from nine large shark species (Carcharhinus limbatus (blacktip), Carcharhinus obscurus (dusky), Carcharhinus brevipinna (spinner), Carcharhinus leucas (Zambezi/bull), Galeocerdo cuvier (tiger), Sphyrna lewini (scalloped hammerhead), Sphyrna zygaena (smooth hammerhead), Carcharodon carcharias (great white) and Carcharias taurus (raggedtooth/grey nurse/sand tiger)) found off the east coast of South Africa. While there was generally little variation between the species, all species showed profiles rich in both n6 and n3 polyunsaturated fatty acids compared to terrestrial commercial meats that have low n3. Thus, utilizing skeletal muscle tissues from sharks caught as part of the bycatch when fishing for teleosts would avoid unnecessary wastage of a potentially valuable resource, with all the possible health benefits of high quality protein combined with balanced polyunsaturates, although contamination with high levels of metabolic wastes, such as urea, may be a negative consideration.

Concentração e retenção do selênio em peixes marinhos

Fish contains considerably higher selenium (Se) concentrations than other kinds of meats, and thus it is considered a major dietary source of this nutrient. At the same time, fish is also the major source of mercury (Hg) in the human diet, whose toxicity can be reduced by the Se through the interaction between both compounds. In consequence, the biological availability of Se is reduced. In the current study, the occurrence of Se was evaluated in commercially available Brazilian marine species, and the retention of Se in sharks (sand tiger shark) was determined. The average levels of Se found in bony fish, gutted corvina ( Micropogonias furnieri), triggerfish ( Balistes capricus), hake and sardine (Sardinella brasiliensis), 0.48 ± 0.18 µg.g –1 , and in cartilaginous fish, small shark (squantina Guggenheim), hammerhead shark, spinner shark, and sand tiger shark, 0.36 ± 0.07 µg.g –1 , did not differ from one another (p > 0.05). In fact, their occurrence was in accordance with the literature data on marine fish. The levels of Se found in the sharks (predatory species) are not enough to establish a stoichiometric relation for the interaction with Hg focusing on the desired toxic protection. The effective Se retention evaluated in the sand tiger shark, after extraction with water, was considered high (minimum of 68.81%) and important taking nutritional and toxicological aspects into account.

Maternal investment and size‐specific reproductive output in carcharhinid sharks

1. Life-history theory predicts that organisms will provide an optimal level of parental investment for offspring survival balanced against the effects on their own survival and future reproductive potential. 2. Optimal resource allocation models also predict an increase in reproductive output with age as expected future reproductive effort decreases. To date, maternal investment in sharks has received limited attention. 3. We found that neonatal dusky sharks (Carcharhinus obscurus) are not independent from maternal resource allocation at the point of parturition but instead are provisioned with energy reserves in the form of an enlarged liver that constitutes approximately 20% of total body mass. 4. Analysis of long-term archived data sets showed that a large proportion of this enlarged liver is utilized during the first weeks or months of life suggesting that the reported weight loss of newborn sharks signifies a natural orientation process and is not necessarily related to prey abundance and/or indicative of high mortality rates. 5. Interrogation of near-term pup mass in two carcharhinids, the dusky and spinner shark (Carcharhinus brevipinna), further revealed an increase in reproductive output with maternal size, with evidence for a moderate decline in the largest mothers. 6. For the dusky shark, there was a trade-off between increasing litter size and near-term pup mass in support of optimal offspring size theory. 7. For both the dusky and spinner shark, there was a linear increase in near-term pup mass with month, which may indicate variable parturition strategies and/or that carcharhinids are able to adjust the length of the gestation period. 8. The identification of optimal size-specific reproductive output has direct implications for improving the reproductive potential of exploited shark populations and for structuring future management strategies.

Determining shark size from forensic analysis of bite damage

Bite damage patterns have long been used to estimate shark species and body size, with somewhat limited success. The lack of fit between damage patterns and shark size is partially due to variation in tooth size and shape within an individual. The ability to accurately predict body size from bite patterns is important for better understanding the ecological and behavioral underpinnings of shark bites/attacks on marine organisms, humans, and submarine equipment. To this end, we measured interdental distance (IDD) between the most labial teeth in the first six tooth files on both the upper and lower jaws, as well as the circumference of the portion of each jaw that bears teeth, for prepared jaw sets from fourteen shark species and regressed these data against total length. IDD is allometric as well as an accurate predictor of total length in all species examined, except Carcharhinus acronotus. Tooth-bearing circumference is also allometric and predictive of total length in all species. Though considerable overlap exists in IDD and circumference ranges among species for the total length ranges examined, Carcharodon carcharias and Isurus sp. can be differentiated from Carcharhinus limbatus, Carcharhinus brevipinna, and C. acronotus based on these values alone. When combined with knowledge of species-specific feeding behavior, geographic distribution, and habitat preferences, these simple measures from bite damage patterns allow quick, accurate assessment of shark size and potential species.

Erection of a New Onchobothriid Genus (Cestoda: Tetraphyllidea) and the Description of Five New Species from Whaler Sharks (Carcharhinidae)

The onchobothriid Triloculatum n. gen. is erected to house species formerly considered members of Phoreiobothrium, but that bear 3, rather than 5 or more, bothridial subloculi. The species formerly known as Phoreiobothrium triloculatum is designated as its type. This species is redescribed based on 2 syntypes and on voucher material consistent with type material taken from the type host, Carcharhinus obscurus, from the type and 1 additional locality. Examination of the cestode fauna of a diversity of carcharhinid sharks resulted in the discovery of an additional 5 new tri-subloculate species belonging to the genus. These include: Triloculatum andersonorum n. sp. from Negaprion acutidens; Triloculatumr bullardi n. sp. from Carcharhinus brevipinna; Triloculatum geeceearelensis n. sp. from Carcharhinus isodon; Triloculatum jodyi n. sp. from Carcharhinus acronotus; and Triloculatum oregontwoae n. sp. from Carcharhinus plumbeus. The new species differ from one another in the number of proglottids, scolex size, number of testes, number of lateral columns of vitelline follicles, and whether they possess craspedote or acraspedote proglottids. Histology and scanning electron microscopy suggest that the new genus differs further from Phoreiobothrium in that its species possess an anterior margin of the posterior loculus that is fused to the anterior loculus, rather than free. The diagnosis of Phoreiobothrium is emended to accommodate the removal of tri-subloculate species and the new information on the condition of the locular interface, and the symmetrical ovary and vitelline follicles arranged in 2 lateral bands; each band consisting of 2 to many columns of follicles. Existing host data indicate that the new genus is restricted to only a subset of the sharks parasitized by species of Phoreiobothrium. Results from the examination of a diversity of carcharhinid species suggest that species in the new genus may have an affinity for the larger, i.e., >200 cm in total length, species of Carcharhinus and Negaprion. One of the new Triloculatum species was found to attach in the crypts lying between the larger ridges found on the mucosal surface of the posterior inner region of the scroll-type spiral intestine of C. brevipinna.

SIZE, SEX AND LENGTH AT MATURITY OF FOUR COMMON SHARKS CAUGHT FROM WESTERN INDONESIA

A study on four common shark species in Indonesia, the spinner shark Carcharhinus brevipinna (Muller and Henle, 1839), silky shark Carcharhinus falciformis (Bibron, 1839), spot-tail shark Carcharhinus sorrah (Valenciennes, 1839) and scalloped hammerhead Sphyrna lewini (Griffith and Smith, 1834) was conducted at several shark landing sites in western Indonesia from March 2002 to December 2004. Data were collected from the surveyed areas including the length of frequency, sex composition and length at maturity. In general, they were caught at size smaller than their maturity size. The proportion of immature C. brevipinna, C. falciformis, C. sorrah and S. lewini to their total number recorded at the surveyed area during the study were about 87%, 50%, 80% and 65%, respectively. According to the length at maturity, females generally attained their maturity in larger size than males. Some factors contributing the catches in immature size and conservation status of those four species were also discussed.

Habitat partitioning among four elasmobranch species in nearshore, shallow waters of a subtropical embayment in Western Australia

There is a need to explore, in an integrated and statistical manner, how the number of species, relative abundance, species composition and life-cycle stages of elasmobranchs in nearshore waters vary among habitat types and during the year. Therefore, four sites in a large marine embayment, each representing a different habitat type, were sampled at regular intervals. These sites were: (1) unvegetated, with no vegetation within at least 200 m; (2) unvegetated, immediately adjacent to sparse mangroves; (3) unvegetated, immediately adjacent to dense mangroves; and (4) vegetated, with seagrass (Posidonia australis) throughout and in the vicinity. Gill netting caught 10 shark species (5 families), 5 ray species (4 families) and 12 teleost species (10 families). Carcharhinus cautus, which contributed approximately 60% to the numbers of elasmobranchs caught, completed its life cycle in nearshore, shallow waters. Negaprion acutidens, Carcharhinus brevipinna, Carcharhinus limbatus and Rhizoprionodon acutus used these waters as a nursery area. C. cautus was caught mainly in the unvegetated sites, particularly in those near mangroves. N. acutidens was caught entirely in unvegetated sites, while R. acutus, C. brevipinna and Chiloscyllium punctatum were caught predominantly or exclusively in seagrass. The mean number of species and mean catch rate of elasmobranchs were greatest for the seagrass site and least for the unvegetated site with no vegetation within at least 200 m and were significantly less for the latter site than for the unvegetated site immediately adjacent to dense mangroves (P<0.05). The numbers of species and catch rates of elasmobranchs were significantly greater in summer and autumn than in winter (P<0.05) and, in the case of number of species, also than in spring (P<0.05). We conclude that the spatial and food resources in the nearshore, shallow waters of Shark Bay are partitioned among elasmobranch species, thus reducing the potential for competition among these species for the resources in those waters.

Foraging ecology of the early life stages of four sympatric shark species

Sharks may have an important role in marine ecosystems in relation to populations of fish and invertebrates at lower trophic levels. Fishery management plans stress the need for an ecosystem approach, but few quantitative studies on the foraging ecology of sharks have been published. Stomach contents and catch data of early life stages of Atlantic sharpnose Rhizoprionodon terraenovae, blacktip Carcharhinus limbatus, finetooth Carcharhinus isodon, and spinner sharks Carcharhinus brevipinna taken from fishery independent surveys in Apalachicola Bay, Florida, USA, were examined to test for overlap in resource use. Young-of-the-year Atlantic sharpnose sharks were found to feed mainly on shrimp, juveniles on sciaenids, and adults on clupeids. Young-of-the-year blacktip sharks were found to feed mainly on sciaenids, whereas juveniles fed on clupeids. The primary prey of young-of-the-year and juvenile finetooth and spinner sharks was clupeids. Eight of 10 prey size-selectivity tests showed neutral selection. Compared to relative prey sizes published for teleost piscivores, Atlantic sharpnose and finetooth sharks consume relatively small-sized prey while blacktip sharks consume relatively large prey. Regardless of maturity state and species, diet overlap was high for species-life stage combinations that are similar in size; however, species-life stages did not show significant habitat overlap. Prey categories shared by similar-sized species may not be limiting, although shark species may have alleviated competition pressure by partitioning the resource of time or space.

DISTRIBUTION AND REPRODUCTIVE BIOLOGY OF THE SPINNER SHARK, CARCHARHINUS BREVIPINNA (MÜLLER AND HENLE, 1841) (CHONDRICHTHYES: CARCHARHINIDAE)

The spinner shark, Carcharhinus brevipinna, is a Lessepsian immigrant formerly common in the Gulf of Gabes (southeastern Tunisia, central Mediterranean). It migrated northward into the Gulf of Tunis as a consequence of competition pressure from its sympatric species, the sandbar shark, C. plumbeus. Adult males and females reach over 1720 mm and 1960 mm total length (TL), respectively. The largest known male and female are 2630 mm and 2750 mm TL, respectively. There is no significant relationship of mass versus TL between males and females. C. brevipinna is a placental viviparous elasmobranch. Adult females have a single functional ovary and two functional uteri, in which encapsulated eggs and embryos are equally distributed. Mating occurs in spring or early summer; parturition, in August. Gestation lasts 13-14 months or longer, and there is a seasonal reproductive cycle. Vitellogenesis proceeds in parallel with gestation. Diameter of the largest yellow-yolked oocytes ranges from 31 to 36 mm (33.3 mm ± 1.4...

Age and growth of the spinner shark Carcharhinus brevipinna (Müller and Henle, 1839) off the KwaZulu-Natal coast, South Africa

Age and growth of the spinner shark Carcharhinus brevipinna off the KwaZulu-Natal coast of South Africa was investigated from vertebral growth ring counts of 67 specimens (54–213 cm precaudal length, PCL). Counts were made from sectioned vertebral centra by two readers. There was a statistically significant difference between the growth functions of both sexes and Von Bertalanffy growth functions were L ∞ = 196.3 cm, k = 0.146 year−1 and t 0 = −2.3 year for males; L ∞ = 232.8 cm, k = 0.1 year−1 and t 0 = −2.9 year for females. This difference was thought to be attributable to initially faster growth rate of males until maturity, after which their growth rate slowed below that of females. Number of growth rings at maturity was 8–10 for both males (150 cm PCL) and females (160 cm PCL). The oldest female and male in the sample had 17 (213 cm PCL) and 19 growth rings (192 cm PCL) respectively. Annual growth ring deposition could not be validated using marginal increment ratio analysis because of the small sam...

The liver lipid fatty acid profiles of seven Indian Ocean shark species

We have assessed the fatty acid profiles of the livers from seven shark species (Carcharias taurus (raggedtooth/grey nurse), Carcharhinus limbatus (blacktip), Carcharhinus obscurus (dusky), Carcharhinus leucas (Zambezi/bull), Sphyrna lewini (scalloped hammerhead), Carcharhinus brevipinna (spinner), and Galeocerdo cuvieri (tiger)) found off the east coast of South Africa. While there was generally little variation between the species, Carcharias taurus showed fatty acid profiles that would be most favourable in human nutrition, in that it showed both low saturated (SFA) (37.1%) and high polyunsaturated fatty acid (PUFA) (26.6%) levels. However, all species showed profiles rich in PUFA, thus utilising the liver oil from sharks caught as part of the bycatch when fishing for teleost species would avoid unnecessary wastage of a potentially valuable resource.

Kroyeria deetsi n.sp. (Kroyeriidae: Siphonostomatoida), a parasitic copepod infecting gills of spinner sharks, Carcharhinus brevipinna (Müller & Henle, 1839), in the Indian Ocean

Kroyeria deetsi n.sp. (Kroyeriidae: Siphonostomatoida) is described from both sexes collected from the gills of spinner sharks, Carcharhinus brevipinna (Müller & Henle, 1839), captured in the Indian Ocean off the coast of South Africa. Kroyeriadeetsi n.sp. can easily be distinguished from all of its congeners because the third endopod segments of legs 1–4 of the new species are about twice (legs 1, 2 and 4), or more than twice (leg 3), as long as the corresponding second endopod segments in the female.

Sharks caught in the protective gill nets off Kwazulu-Natal, South Africa. 9. The spinner shark Carcharhinvs brevipinna (Müller and Henle)

A total of 2 728 spinner sharks Carcharhinus brevipinna was caught in nets that protect the swimming beaches of KwaZulu-Natal between 1978 and 1997. The species constituted 10.3% of the total shark catch during that period. An average of 136 spinner sharks was caught annually, with no trend in catch rate over the study period. The species was caught throughout the year, predominantly in the south and mainly from February to July. Males matured at approximately 150 cm precaudal length and females at 154 cm. Gonad indices in mature males were highest during December and January and in females during February and March. Mating takes place between January and March. The hepatosomic index of pregnant females was highest at the onset of pregnancy and lowest at parturition. Evidence suggests a two-year reproductive cycle in females, with a gestation period of 13–18 months. The average litter size was nine, with an estimated length at birth of between 50 and 60 cm. Near-term pregnant females were caught mainly in the north, indicating the possibility of a nursery there. Both large and small pregnant females produce pups of the same length, but larger females general1y have larger litters. Regional, seasonal and size variations were evident in the diet, with teleosts being the most frequently eaten prey.