Life history and diet of two southern African smoothhound sharks, mustelus mustelus (linnaeus, 1758) And mustelus palumbes smith, 1957

Aspects of the life history and biology of two sympatric coastal shark species (Mustelus mustelus and M. palumbes) off southern Africa are described and compared. Free-swimming male M. mustelus measured390–1 450 mm total length (TL), whereas females were recorded up to 1 650 mm TL. Most specimens of both sexes were found at depths shallower than 100 m. Males mature at 950–1 300 mm TL and females at1 250–1 400 mm TL. Reproduction is seasonal, and each cycle may take one year or longer, if there is a resting period between pregnancies. Litter size was correlated with female size and varied between 2 and 23. Thelargest embryo measured 425 mm TL. The hepatosomatic indices were negatively correlated to embryo length in both species. Prey was dominated by crustaceans, although cephalopods became important in larger M. mustelus. There was a good relationship between prey size and fish size. Free swimming male M. palumbes measured 275–1 008 mm TL, whereas females were recorded up to 1 126 mm TL. M. palumbes males were most often taken from 100–180 m deep and females from 60–140 m. Males mature at 750–850 mm TL and females at 800–100 mm TL. Reproduction appears to be aseasonal in M. palumbes and litters of 3–15 young were recorded, with larger females having larger litters. The largest embryo recorded measured 340 mm TL.The timing of reproductive cycles could not be established, but a high proportion of non-pregnant femalessuggests that there may be a resting period following pregnancy. Crustaceans were the dominant prey type recorded, although larger predators ate a wider variety of prey types than smaller individuals. Although there was overlap in the prey taken by the two shark species, the composition of the diet was strongly influenced by the prey available in different habitats

First records of the longnose spiny dogfish Squalus blainvillei (Squalidae) and the deep-water stingray Plesiobatis daviesi (Urolophidae) from South African waters

Deep-set longline investigations of the slope waters off northern KwaZulu-Natal on the east coast of South Africa confirmed the first records of the longnose spiny dogfish Squalus blainvillei (Squalidae) and the deepwater stingray Plesiobatis daviesi (Urolophidae) from South African waters.Keywords: first records, Plesiobatis daviesi, Squalus blainvillei, South AfricaAfrican Journal of Marine Science 2002, 24: 355–35

Global Diversity Hotspots and Conservation Priorities for Sharks

Sharks are one of the most threatened groups of marine animals, as high exploitation rates coupled with low resilience to fishing pressure have resulted in population declines worldwide. Designing conservation strategies for this group depends on basic knowledge of the geographic distribution and diversity of known species. So far, this information has been fragmented and incomplete. Here, we have synthesized the first global shark diversity pattern from a new database of published sources, including all 507 species described at present, and have identified hotspots of shark species richness, functional diversity and endemicity from these data. We have evaluated the congruence of these diversity measures and demonstrate their potential use in setting priority areas for shark conservation. Our results show that shark diversity across all species peaks on the continental shelves and at mid-latitudes (30–40 degrees N and S). Global hotspots of species richness, functional diversity and endemicity were found off Japan, Taiwan, the East and West coasts of Australia, Southeast Africa, Southeast Brazil and Southeast USA. Moreover, some areas with low to moderate species richness such as Southern Australia, Angola, North Chile and Western Continental Europe stood out as places of high functional diversity. Finally, species affected by shark finning showed different patterns of diversity, with peaks closer to the Equator and a more oceanic distribution overall. Our results show that the global pattern of shark diversity is uniquely different from land, and other well-studied marine taxa, and may provide guidance for spatial approaches to shark conservation. However, similar to terrestrial ecosystems, protected areas based on hotspots of diversity and endemism alone would provide insufficient means for safeguarding the diverse functional roles that sharks play in marine ecosystems

Shark Attacks in Dakar and the Cap Vert Peninsula, Senegal: Low Incidence despite High Occurrence of Potentially Dangerous Species

The International Shark Attack File mentions only four unprovoked shark attacks on the coast of West Africa during the period 1828–2004, an area where high concentrations of sharks and 17 species potentially dangerous to man have been observed. To investigate if the frequency of shark attacks could be really low and not just under-reported and whether there are potentially sharks that might attack in the area, a study was carried out in Dakar and the Cap Vert peninsula, Senegal. and 3 with unidentified sharks.These findings suggest that the frequency of shark attacks on the coast of West Africa is underestimated. However, they also indicate that the risk is very low despite the abundance of sharks. In Dakar area, most encounters along the coastline with potentially dangerous species do not result in an attack. Compared to other causes of water related deaths, the incidence of shark attack appears negligible, at least one thousand fold lower

Age and growth of the smooth hammerhead, Sphyrna zygaena, in the Atlantic Ocean: comparison with other hammerhead species

The smooth hammerhead Sphyrna zygaena (Sphyrnidae) is a pelagic shark occasionally caught as bycatch in pelagic longline fisheries, but is one of the least studied of all pelagic sharks. Age and growth of S. zygaena was studied along a wide Atlantic region covering both the northern and southern hemispheres. Data from 304 specimens, caught between October 2009 and September 2014, ranging in size from 126 to 253 cm fork length (FL), were analysed. Growth models were fitted using the three-parameter von Bertalanffy growth function (VBGF) re-parameterized to calculate L0 (size at birth). Growth models were fitted to the sample data and data from several back-calculation models. The model fit to the quadratic modified Dahl-Lea back-calculated data seems to be the most appropriate to describe growth in this species, with resulting growth parameters of Linf = 285 cm FL, k = 0.09 year−1 for males and Linf = 293 cm FL, k = 0.09 year−1 for females. Compared with other species of the same genus, estimated growth coefficients for S. zygaena seem to fall in the low to middle range. Although further work is still needed, this study adds to knowledge of the vital life-history parameters of smooth hammerheads in the Atlantic Ocean, which can be used in the management and conservation of this species.Programa Operacional Potencial Humano: IF/00253/2014info:eu-repo/semantics/publishedVersio

High Post-Capture Survival for Sharks, Rays and Chimaeras Discarded in the Main Shark Fishery of Australia?

Most sharks, rays and chimaeras (chondrichthyans) taken in commercial fisheries are discarded (i.e. returned to the ocean either dead or alive). Quantifying the post-capture survival (PCS) of discarded species is therefore essential for the improved management and conservation of this group. For all chondrichthyans taken in the main shark fishery of Australia, we quantified the immediate PCS of individuals reaching the deck of commercial shark gillnet fishing vessels and applied a risk-based method to semi-quantitatively determine delayed and total PCS. Estimates of immediate, delayed and total PCS were consistent, being very high for the most commonly discarded species (Port Jackson shark, Australian swellshark, and spikey dogfish) and low for the most important commercial species (gummy and school sharks). Increasing gillnet soak time or water temperature significantly decreased PCS. Chondrichthyans with bottom-dwelling habits had the highest PCS whereas those with pelagic habits had the lowest PCS. The risk-based approach can be easily implemented as a standard practice of on-board observing programs, providing a convenient first-step assessment of the PCS of all species taken in commercial fisheries

A Streamlined DNA Tool for Global Identification of Heavily Exploited Coastal Shark Species (Genus Rhizoprionodon)

Obtaining accurate species-specific landings data is an essential step toward achieving sustainable shark fisheries. Globally distributed sharpnose sharks (genus Rhizoprionodon) exhibit life-history characteristics (rapid growth, early maturity, annual reproduction) that suggests that they could be fished in a sustainable manner assuming an investment in monitoring, assessment and careful management. However, obtaining species-specific landings data for sharpnose sharks is problematic because they are morphologically very similar to one another. Moreover, sharpnose sharks may also be confused with other small sharks (either small species or juveniles of large species) once they are processed (i.e., the head and fins are removed). Here we present a highly streamlined molecular genetics approach based on seven species-specific PCR primers in a multiplex format that can simultaneously discriminate body parts from the seven described sharpnose shark species commonly occurring in coastal fisheries worldwide. The species-specific primers are based on nucleotide sequence differences among species in the nuclear ribosomal internal transcribed spacer 2 locus (ITS2). This approach also distinguishes sharpnose sharks from a wide range of other sharks (52 species) and can therefore assist in the regulation of coastal shark fisheries around the world

New Mediterranean Marine biodiversity records

Based on recent biodiversity studies carried out in different parts of the Mediterranean, the following 19 species are included as new records on the floral or faunal lists of the relevant ecosystems: the green algae Penicillus capitatus (Maltese waters); the nemertean Amphiporus allucens (Iberian Peninsula, Spain); the salp Salpa maxima (Syria); the opistobranchs Felimida britoi and Berghia coerulescens (Aegean Sea, Greece); the dusky shark Carcharhinus obscurus (central-west Mediterranean and Ionian Sea, Italy); Randall’s threadfin bream Nemipterus randalli, the broadbanded cardinalfish Apogon fasciatus and the goby Gobius kolombatovici (Aegean Sea, Turkey); the reticulated leatherjack Stephanolepis diaspros and the halacarid Agaue chevreuxi (Sea of Marmara, Turkey); the slimy liagora Ganonema farinosum, the yellowstripe barracuda Sphyraena chrysotaenia, the rayed pearl oyster Pinctada imbricata radiata and the Persian conch Conomurex persicus (south-eastern Kriti, Greece); the blenny Microlipophrys dalmatinus and the bastard grunt Pomadasys incisus (Ionian Sea, Italy); the brown shrimp Farfantepenaeus aztecus (north-eastern Levant, Turkey); the blue-crab Callinectes sapidus (Corfu, Ionian Sea, Greece). In addition, the findings of the following rare species improve currently available biogeographical knowledge: the oceanic pufferfish Lagocephalus lagocephalus (Malta); the yellow sea chub Kyphosus incisor (Almuñécar coast of Spain); the basking shark Cetorhinus maximus and the shortfin mako Isurus oxyrinchus (north-eastern Levant, Turkey)

Classification of Sharks in the Egyptian Mediterranean Waters Using Morphological and DNA Barcoding Approaches

The identification of species constitutes the first basic step in phylogenetic studies, biodiversity monitoring and conservation. DNA barcoding, i.e. the sequencing of a short standardized region of DNA, has been proposed as a new tool for animal species identification. The present study provides an update on the composition of shark in the Egyptian Mediterranean waters off Alexandria, since the latest study to date was performed 30 years ago, DNA barcoding was used in addition to classical taxonomical methodologies. Thus, 51 specimen were DNA barcoded for a 667 bp region of the mitochondrial COI gene. Although DNA barcoding aims at developing species identification systems, some phylogenetic signals were apparent in the data. In the neighbor-joining tree, 8 major clusters were apparent, each of them containing individuals belonging to the same species, and most with 100% bootstrap value. This study is the first to our knowledge to use DNA barcoding of the mitochondrial COI gene in order to confirm the presence of species Squalus acanthias, Oxynotus centrina, Squatina squatina, Scyliorhinus canicula, Scyliorhinus stellaris, Mustelus mustelus, Mustelus punctulatus and Carcharhinus altimus in the Egyptian Mediterranean waters. Finally, our study is the starting point of a new barcoding database concerning shark composition in the Egyptian Mediterranean waters (Barcoding of Egyptian Mediterranean Sharks [BEMS], http://www.boldsystems.org/views/projectlist.php?&#Barcoding%20Fish%20%28FishBOL%29)

The Shark Assemblage at French Frigate Shoals Atoll, Hawai‘i: Species Composition, Abundance and Habitat Use

Empirical data on the abundance and habitat preferences of coral reef top predators are needed to evaluate their ecological impacts and guide management decisions. We used longline surveys to quantify the shark assemblage at French Frigate Shoals (FFS) atoll from May to August 2009. Fishing effort consisted of 189 longline sets totaling 6,862 hook hours of soak time. A total of 221 sharks from 7 species were captured, among which Galapagos (Carcharhinus galapagensis, 36.2%), gray reef (Carcharhinus amblyrhynchos, 25.8%) and tiger (Galeocerdo cuvier, 20.4%) sharks were numerically dominant. A lack of blacktip reef sharks (Carcharhinus melanopterus) distinguished the FFS shark assemblage from those at many other atolls in the Indo-Pacific. Compared to prior underwater visual survey estimates, longline methods more accurately represented species abundance and composition for the majority of shark species. Sharks were significantly less abundant in the shallow lagoon than adjacent habitats. Recaptures of Galapagos sharks provided the first empirical estimate of population size for any Galapagos shark population. The overall recapture rate was 5.4%. Multiple closed population models were evaluated, with Chao Mh ranking best in model performance and yielding a population estimate of 668 sharks with 95% confidence intervals ranging from 289–1720. Low shark abundance in the shallow lagoon habitats suggests removal of a small number of sharks from the immediate vicinity of lagoonal islets may reduce short-term predation on endangered monk seal (Monachus schauinslandi) pups, but considerable fishing effort would be required to catch even a small number of sharks. Additional data on long-term movements and habitat use of sharks at FFS are required to better assess the likely ecological impacts of shark culling