White shark (Carcharodon carcharias)-inflicted bite wounds observed on Cape fur seals (Arctocephalus pusillus pusillus) at Black Rocks,Algoa Bay,South Africa

This paper presents the first quantitative study on the seasonal occurrence and body location of white shark (Carcharodon carcharias)-inflicted injuries on Cape fur seals (Arctocephalus pusillus pusillus) at Black Rocks, in Algoa Bay. Between January 2010 and October 2011, 22 boat trips were made to Black Rocks to chum for white sharks. On 19 of the trips a series of overlapping photographs were taken of the northern side of Black Rocks and the percentage of seals, which exhibited fresh white shark bite wounds recorded. A total of 53 sharks and 28 fresh shark-inflicted injuries were recorded on seals over the course of the study period. The maximum number of sharks sighted per hour (1.2) was in July and the highest percentage of shark bitten seals in November (0.6%). There was no significant relationship between the monthly sighting rate of sharks and the percentage of shark bitten seals (P = 0.40). The percentage of shark-inflicted injuries observed on seals increased with seal size. Most injuries were observed in the forebody (37.5%) and lower body regions (37.5%). Very few injuries (6.3%) were observed in the head and neck region. The low number of bite-inflicted injuries observed suggests that white sharks attack seals infrequently at Black Rocks.     

Save the sharks: reevaluating and (re)valuing feared predators

Much of the history of the human–shark relationship has been based on fear. For centuries, the goal has been to kill sharks that come near boats or beaches. Yet, there is a growing trend of more positive feelings toward local shark populations. In this article, we demonstrate that feelings of pride toward sharks can serve as an opposing force to fear, and can moderate the way fear affects support for policies to kill sharks. This study reports on two surveys of pride toward sharks from Eastern and Western Australia. These highlight a new and emerging story for people and sharks. We argue that the combination of shifts in the understanding of sharks’ motives during human–shark interactions and higher levels of pride support a new political dynamic in which the public prefers nonlethal responses to shark bites in support of a burgeoning “save the sharks” movement.     

Beach-User Attitudes to Shark Bite Mitigation Strategies on Coastal Beaches; Sydney,Australia

Common strategies to protect swimmers from unprovoked shark bite incidents on coastal beaches are controversial. We surveyed beach users on two Sydney beaches to gauge their knowledge and attitudes to current and topical shark bite mitigation strategies. Most interviewees (>55%) were aware that shark nets were deployed on each beach, and gave relatively strong (>60%) support for their use. In contrast, beach users were overwhelming against (>80%) the general culling of sharks, and also opposed (>70%) the strategy of catching and killing sharks following a shark bite incident. There was little difference between genders in their attitudes to each strategy, but the oldest age category (51+) surveyed was generally most supportive of the lethal strategies. The results demonstrated the dichotomies in public attitudes to the different mitigation strategies, particularly passive versus active culling, and highlighted the need for greater public education for the development of socially acceptable solutions to shark hazards.     

Influence of supraphysiological cortisol manipulation on predator avoidance behaviors and physiological responses to a predation threat in a wild marine teleost fish

The stress axis in teleost fish attempts to maintain internal homeostasis in the face of allostatic loading. However, stress axis induction has been associated with a higher predation rate in fish. To date, the physiological and behavioral factors associated with this outcome are poorly understood. The purpose of the present study was to investigate the impact of experimental cortisol elevation on anti‐predator behavior and physiological responses to predator presence. We hypothesized that semi‐chronic cortisol elevation would increase susceptibility to predation by increasing stress‐induced risk‐taking behaviors. To test this hypothesis, schoolmaster snapper were given cocoa butter implants without cortisol (sham) or with cortisol (50 mg/kg body weight) and tethered to cover. Fish were exposed to either a lemon shark or control conditions for 15‐min. Space use and activity were recorded throughout and fish were terminally sampled for blood. Cortisol implantation, relative to shams, resulted in higher blood glucose and plasma cortisol concentrations with a lower plasma lactate concentration. Shark exposure, relative to controls, elicited higher blood glucose and lactate concentrations but had no effect on plasma cortisol concentration. No interactions were detected between shark exposure and cortisol treatment for any physiological trait. Behavioral metrics, including shelter use and activity, were unaffected by either cortisol implantation or shark exposure. Physiological responses to cortisol implantation likely resulted from enhanced gluconeogenic activity, whereas alterations under predator exposure may have been the product of catecholamine mobilization. Further work should address context‐specific influences of stress in mediating behavioral responses to predation.     

ULTRASONOGRAPHY AS A DIAGNOSTIC TOOL IN SHARK SPECIES

The use of sonography was evaluated in eleven sharks as a potential diagnostic and investigative tool. Individual sharks were anesthetized with MS-222 (Tricane Methane Sulphonate) and sonograms recorded from various planes using a 3 MHZ linear array scanner. Sonographic images were compared with corresponding postmortem cross sections. Heart rate and rhythm were monitored with real time sonography in an attempt to gauge the depth of the anesthesia. Heart rates ranged from 12–46 bpm. Initial results of this study suggest that sonography may be a useful technique in shark species where the application of radiographic techniques is limited by the lack of adipose tissue and the need to maintain the animal in water.     

A short note on the horizontal and vertical movements of a whale shark, Rhincodon typus, tracked by satellite telemetry in the South China Sea

Whale sharks, a global migratory species, are often reported entangled in fishing nets in coastal areas of China. The effectiveness of conservation measures has been constrained by very limited knowledge on their movements and preferred habitats in the coastal areas of China. For the first time, we tracked the movements of 2 whale sharks by satellite telemetry in Mainland China. The tracking results of 1 whale shark revealed that it travelled in the South China Sea in a south-eastern direction, parallel to the eastern coast of Vietnam. Total distance travelled was 1018 km, in approximately 74 days, with a mean speed of 14 km per day. It appeared to head towards the cool upwelling zones in southern Vietnam at the time of the tag's detachment. In our study, it was observed that this whale shark was a surface dweller and spent approximately 45% of its time above 10 m water depth and 90% of its time above 50 m depth. It also tended to stay in water temperatures between 27 and 30 °C, and was rarely recorded in water below 20 °C. This preliminary study indicates the importance of shallow waters as the foraging habitat for whale sharks, and has implications for their management and conservation.     

Differences in hematocrit of blood samples obtained from two venipuncture sites in sharks

OBJECTIVE: To evaluate differences in Hct between 2 venipuncture sites in captive and free-ranging sharks. ANIMALS: 32 healthy adult captive sharks (Carcharhinus melanopterus, Carcharhinus plumbeus, Stegastoma fasciatum, Orectolobus japonicus, and Triaenodon obesus) and 15 captured free-ranging adult sharks (Carcharhinus limbatus and Carcharhinus acronotus). PROCEDURES: Blood samples were collected from the caudal tail artery followed by collection from the sinus located immediately caudal to the cranial dorsal fin. The Hct was determined for each sample and results were compared. Additionally, results for sharks that were highly active and used aerobic metabolism were compared with results for sharks that were less active and tolerant of anaerobic conditions. RESULTS: Mean Hct for all sharks was significantly less (8% less) in blood samples obtained from the cranial dorsal fin sinus, compared with the Hct for samples obtained from the caudal tail artery. When compared on the basis of metabolic class, sharks that were more tolerant of anaerobic conditions had lower Hct values and smaller differences between the 2 venipuncture sites. CONCLUSIONS AND CLINICAL RELEVANCE: Hct values were significantly lower in blood samples collected from the cranial dorsal fin sinus compared with values for samples collected from the caudal tail artery. It is important to recognize this difference when evaluating hematologic variables in sharks and when establishing reference ranges for Hcts for shark populations. Sharks that were more active and relied on aerobic metabolism had higher Hct values than did anaerobic-tolerant sharks, and the difference in Hct values between venipuncture sites was more pronounced.     

Clinical and cardiorespiratory effects of propofol in the spotted bamboo shark (Chylloscyllium plagiosum).

Sharks are important exhibit animals in aquariums and zoologic institutions worldwide. Although veterinarians are encountering these species more frequently in these institutions, our knowledge regarding safe restraint and anesthesia is limited. To date there have been only a few anecdotal reports or studies evaluating the effects of tricaine methane sulfonate (MS-222), ketamine hydrochloride, and tiletamine and zolazepam (Telazol) in sharks. The purpose of this study was to evaluate the clinical and cardiorespiratory effects of propofol in spotted bamboo sharks (Chylloscyllium plagiosum). Nine wild-caught adult female spotted bamboo sharks (mean weight 2.4 kg+/-SD 1.45 kg) were used in this study. Propofol (2.5 mg/kg) was administered over 30 sec via the caudal tail vein. Heart rate, respiratory rate, time to relaxation, escape response, loss of righting reflex, and response to noxious stimuli (fin pinch) were evaluated and recorded at baseline and 5, 10, 15, 30, 45, 60, and 75 min after propofol administration. A surgical plane of anesthesia was achieved when the shark lost its righting reflex, did not respond to noxious painful stimuli, and no longer resisted handling. The righting reflex was lost within 5 min of propofol administration, and a surgical plane of anesthesia was observed in all nine sharks. Heart rate (P = 0.5) and respiratory rate (P = 0.5) did not change significantly over time. The righting response returned within 60 min in 44% (4/9) of the sharks, 75 min in 22% (2/ 9) of the sharks, and over 200 min in 33% (3/9) of the sharks. All nine animals recovered uneventfully. Propofol provided a safe anesthetic event for spotted bamboo sharks.     

Lesions Associated with Attachment of the Parasitic Copepod Phyllothyreus cornutus (Pandaridae: Siphonostomatoida) to Interbranchial Septa of Blue Sharks

Abstract

Lesions associated with the parasitic copepod Phyllothyreus cornutus on the interbranchial septa of blue sharks Prionace glauca were observed in detail. Female copepods were associated with grossly visible, soft, papillomatous lesions on the interbranchial septum in which their second antennae were embedded. Attached male copepods were either not associated with any appreciable lesions or were attached within shallow ulcerations. Histologically, the papillomatous lesions were marked by epithelial hyperplasia over a lamina propria replaced by granulation tissue or fibrosis with lymphoid nodules. Lesions associated with male copepods consisted of epithelial ulceration and subacute, necrotizing, heterophilic branchitis. Lesions associated with female copepods appeared suggestive of long-term local attachment whereas those associated with males were suggestive of more ephemeral associations with the fish. The observed lesions did not appear capable of impairing respiration; however, the overall impact of Phyllothyreus cornutus infections on the well-being of the blue shark remains unknown.     

Comparison of age determination techniques for known-age Cape fur seals

Known-age teeth were used to validate age determination techniques for the Cape fur seal (Arctocephalus pusillus pusillus). Thin sectioning and staining of decalcified teeth produced the poorest age estimates. For etched half canines, only upper canines could be used to estimate age with good results, and coating improved the accuracy. Scanning electron microscopy produced poor accuracy in age estimation. External ridges reflected age accurately only in younger age classes and should only be used to verify counts of internal growth layer groups, or when rapid, preliminary estimates of age are necessary. This study has highlighted the importance of comparing different age determination techniques and validating such techniques with known-age animals. The reliability with which age can be estimated for the Cape fur seal has also been improved.     

Theoretical Aspects of the Control of Glossina Morsitans by Game Destruction

One way to avoid potential predators is to be sensitive to odour cues, particularly those in faeces and urine, left by predators. This sensitivity has been demonstrated in many solitary, nocturnal, small mammals which may fall victim to ambush predators.We tested the response of Cape ground squirrels, a diurnal, group-living small mammal, to the presence of predator (black-backed jackal) faeces and non-predator (black wildebeest) dung in baited traps, and also predator faeces and non-predator dung outside their burrows. The squirrels showed a significantly higher avoidance of traps scented with predator faeces than both control and non-predator dung-scented traps. They also took significantly longer to emerge from burrows that had predator faeces outside compared with control burrows and burrows with non-predator dung outside and showed a trend for higher vigilance once they emerged from burrows with predator faeces outside. We argue that as diurnal group-living reduces a reliance on olfactory cues, this species is more likely to rely on visual cues and the vigilance of other individuals than nocturnal solitary species that have been the focus of most studies up till now. As a result, squirrels very quickly return to normal behaviour after exposure to a predator cue. Level of sociality is likely to influence responses to olfactory cues of predators and should be the focus of further studies.     

Streptococcus phocae infections associated with starvation in Cape fur seals

Mortalities and abortions associated with starvation occurred at Cape Cross, Namibia, in Cape fur seals (Arctocephalus pusillus pusillus). Affected seals showed lethargy and emaciation, and the most common pathological signs were those of a respiratory infection, both in adults and offspring. Streptococcus phocae was isolated from adult seals, a cub and aborted foetuses.     

Shark and skate egg-cases cast up on two South African beaches and their rates of hatching success,or causes of death

Collections of chondrichthyan egg-cases cast ashore at two sites along the South African coastline were identified and examined for cause of mortality. A total of 574 egg-cases collected from False Bay could be attributed to five species of scyliorhinid shark, two skates and the elephantfish or chimaera, while the 538 egg-cases collected from Port Alfred belonged to four scyliorhinid sharks and two skate species. At both sites eggs of shy-sharks of the genus Haploblepharus made up more than 70% of the samples, followed by skates (5% in False Bay and 19% in Port Alfred) and then catsharks of the genus Poroderma (1 and 7% respectively). Haploblepharus egg-cases generally displayed relatively high rates of hatching success of over 60% and predation rates of 18-30%. Haploblepharus fuscus was the exception with a low hatching success of 37% and a predation rate of 40%. Poroderma egg-cases suffered predation losses of 43%, and had a hatching success of 47%. Skate egg-cases displayed non-predator induced egg mortalities of up to 35%, but predation rates of less than 14%. Hatching success was moderate at 57%. The holes found in egg-cases could be categorised into five types, of which four were clearly predator boreholes. The most abundant of these was shown to be caused by whelks of the genus Bumupena.     

An analysis of faecal pellets of the brown hyaena on the Namib coast

An analysis of faecal pellets of the brown hyaena on the Namib coast showed that Cape fur seals and seabirds constitute a major portion of the diet of this animal.     

Hematology of the sandbar shark, Carcharhinus plumbeus: standardization of complete blood count techniques for elasmobranchs

BACKGROUND: Standardized hematologic methods and reference intervals have not been established for cartilaginous fishes (sharks, skates, and rays) despite the large number of animals displayed in zoos and aquariums worldwide. OBJECTIVE: The focus of this study was to validate CBC methods for sandbar shark (Carcharhinus plumbeus) blood, based on criteria established in human medicine, for the following tests: RBC count, total WBC count, PCV, hemoglobin (Hgb) concentration, and WBC differential percentages. METHODS: Replicate CBCs were performed using blood samples from 5 captive sandbar sharks. Three protocols for RBC and total WBC counts were compared, as were different centrifugation times for PCV determination, and 2 methods for Hgb concentration. Means, minimum and maximum values, and CVs were compared to CAP and CLIA performance guidelines for human tests. RESULTS: Total WBC counts in a diluent modified for elasmobranch blood, Hgb concentration by the cyanmethemoglobin method after removal of nuclei, and WBC differential percentages showed acceptable performance. PCV results were acceptable when tubes were centrifuged for at least 5 minutes. Total RBC counts by all 3 methods exceeded the acceptable error for manual counts of human cells. CONCLUSIONS: Standardized CBC tests can be used as health assessment tools for elasmobranchs. Total RBC counts should be viewed as estimates.     

The influence of the hemoglobin concentration in growing mink kits on certain skin characteristics

The relationship between some skin characteristics and hemoglobin values during the growth period were statistically examined in standard male minks. Significant correlations) (P < 0.05–0.001) were found between the hemoglobin concentrations determined at 3 points during the growth period (in July, August and November) and the density and colour of underfur, and skin length, respectively. According to the study even the early hemoglobin values in July and August have a significant influence on the size and quality of the pelt. Mink kits with low hemoglobin values are liable to develop a winter fur coat with defective pigmentation and hair structure of the underfur. Anemic minks develop the most extreme stage of the pigmentation defect and these so-called cotton fur skins have little value in the fur garment industry. When these abnormal hemoglobin values are recognized at an early stage, cotton fur skins may be avoided, and larger skins of better quality may be produced.     

Disseminated fungal infection in two species of captive sharks

In this report, two cases of systemic mycosis in captive sharks are characterized. These cases were progressive and ultimately culminated in terminal disease. Paecilomyces lilacinus, an uncommon pathogen in human and veterinary medicine, was associated with areas of necrosis in the liver, heart, and gill in a great hammerhead shark (Sphyrna mokarran). Fungal growth was observed from samples of kidney, spleen, spinal fluid, and coelomic cavity swabs. Dual fungal infection by Exophiala pisciphila and Mucor circinelloides was diagnosed in a juvenile zebra shark (Stegostoma fasciatum). Both fungi were present in the liver, with more severe tissue destruction associated with E. pisciphila. E. pisciphila also produced significant necrosis in the spleen and gill, while M. circinelloides was associated with only minimal tissue changes in the heart. Fungal cultures from liver, kidney, and spleen were positive for both E. pisciphila and M. circinelloides. Identification of P. lilacinus and M. circinelloides was based on colonial and hyphal morphology. E. pisciphila was identified by sequence analysis of the 28S rRNA D1/D2 region and the internal transcribed spacer (ITS) region between the 18S and 28S rRNA subunit. These cases, and a lack of information in the literature, highlight the need for further research and diagnostic sampling to further characterize the host-pathogen interaction between elasmobranchs and fungi.     

Identifying predators - a role for veterinary pathologists (abstract)

Predator identification has traditionally been the domain of ecologists who have relied on the feeding sign left by various predator species at the nest or carcass. Thus destructive animals such as cats and dogs can be distinguished from relatively clean predators such as mustelids and messy predators such as possums and rats. The presence of scats or foot imprints, and the location of the nest or carcass are also useful signs, however in many cases it may be impossible to distinguish between predators and scavengers. New technology such as time-lapse photography and video surveillance are valuable tools but still cannot monitor every event. Veterinary pathology can play a useful role by carefully examining and recording the site and severity of lesions and distinguishing between ante- and post mortem tissue damage, using histopathology if necessary. Distances between the canine teeth can be measured from bite marks in the skin and subcutaneous tissues, and mammalian fur on the claws and beak of larger birds can be identified by measuring fibre length and diameter.     

Infectious factor diseases in domestic small animals (carnivorous and herbivorous fur animals, wool and meat rabbits

Infectious factorial diseases of domesticated small animals are infection dependent diseases, whose pathogenesis is finally activated by additional, secondary factors, that influence the multiplying and spreading of latent and clinical symptomless infective agents present in the animals. These factorial diseases are not autonomous infectious processes, but only special types and courses of diseases by secondary activated infective agents. Secondary factors may be of exogenous origin (housing, climate, feeding, managing) or may arise by endogenic processes (immunity, resistance disregulations a.o.). In fur bearing animals and rabbits infectious factorial diseases arise by activation of latent, symptomless infections of mucosal membranes in the nose and oral cavity, in the intestinal tract, in the descending urinary tract and on the external skin. The majority of infection activating secondary factors go back on wrong housing conditions, extreme climate, malnutrition and simultaneous infections, but also animal specific situations and immunosuppression may influence the activation of latent infections. - Typical factorial diseases in fur bearing animals and rabbits are: the infectious coryza (Pasteurella multocida, Bordetella bronchiseptica) in rabbits, the Coli-dysentery and the enterotoxemia in rabbits and herbivorous fur animals, the ascending infections of urinary tract, particular in young male minks, and the different types of microbial dermatitis in all small animals. - In the prevention and control of infectious factorial diseases the improvement of housing and living conditions as well as feeding the animals with species conforming and nonobjectionable food are most important and essential measures.