The biology and ecology of the basking shark: A review.

Here we review the literature on the basking shark (Cetorhinus maximus, Gunnerus, 1765), well known as the second largest extant shark (and fish) species globally. Previous reviews were published by Kunzlik in 1988 and Sims in 2008, but in the last 15 years modern electronic and DNA sequencing technologies have resulted in considerable advances in our knowledge of the species' behaviour and ecology. Basking sharks are planktivores and under appropriate conditions spend prolonged periods at the ocean surface feeding on copepod prey that primarily make up their diet, the behaviour that gave rise to their common name. In general, they are migratory and move into higher latitude waters during the summer months, when loose surface-feeding aggregations may form at favoured sites, the best known of which at present occur at hotspots on the west coasts of Britain and Ireland. The species is found circumglobally in temperate waters, but they are also now known on occasion to migrate at depth between northern and southern hemispheres, as well as across oceans within the northern hemisphere. In the past basking shark were more abundant across much of their range, but, consequent on targeted fisheries and in some places intentional eradication, became everywhere scarce, with recent population recovery in the north-east Atlantic being the result of protective measures initiated in the 1990s. Despite their charismatic nature, some of their most fundamental biological processes including copulation, gestation and birth remain largely unknown, due to their migratory and often deep-water lifestyle. In contrast, the deployment of small-scale archival and satellite tags has revealed the details of both broadscale migratory movements and horizontal and vertical foraging behaviours. Recent genetic studies support evidence suggesting a degree of site fidelity in relation to seasonal feeding grounds, which likely explains why in the past local populations have collapsed following periods of intensive fishing. Other recent research using aerial drones and towed cameras has revealed within loose feeding aggregations elements of social behaviour that may have a courtship function as well as enhance feeding efficiency.

Individual residency behaviours and seasonal long-distance movements in acoustically tagged Caribbean reef sharks in the Cayman Islands.

Understanding how reef-associated sharks use coastal waters through their ontogeny is important for their effective conservation and management. This study used the horizontal movements of acoustically tagged Caribbean reef sharks (Carcharhinus perezi) to examine their use of coastal space around the Cayman Islands between 2009 and 2019. A total of 39 (59.1%) tagged sharks (male = 22, female = 17, immature = 18, mature = 21) were detected on the islands wide network of acoustic receivers. The detection data were used to calculate values of Residency Index (RI), Site-Fidelity Index (SFI) and minimum linear displacement (MLD), as well as for network analysis of individual shark movements to test for differences between demographics, seasons, and diel periods. Sharks were detected for up to 1,598 days post-tagging and some individuals showed resident behaviour but the majority of tagged individuals appear to have been one-off or only occasional transient visitors to the area. Generally, individuals showed strong site-fidelity to different areas displaying linear home ranges of < 20 km. The evidence indicates that there was no pattern of diel behaviour. Tagged sharks generally showed increased movements within and between islands during the summer (April-September), which may be related to breeding activity. Some individuals even made occasional excursions across 110 km of open water > 2,000 m deep between Grand Cayman and Little Cayman. One mature female shark showed a displacement of 148.21 km, the greatest distance reported for this species. The data shows that the distances over which some sharks moved, greatly exceeded the extent of any one of the islands' marine protected areas indicating that this species may be more mobile and dispersive than previously thought. This study provides support for the blanket protection to all sharks throughout Cayman waters, which was incorporated within the National Conservation Act in 2015.

Phylogenomics of the genus Tursiops and closely related Delphininae reveals extensive reticulation among lineages and provides inference about eco-evolutionary drivers.

Phylogeographic inference has provided extensive insight into the relative roles of geographical isolation and ecological processes during evolutionary radiations. However, the importance of cross-lineage admixture in facilitating adaptive radiations is increasingly being recognised, and suggested as a main cause of phylogenetic uncertainty. In this study, we used a double digest RADseq protocol to provide a high resolution (~4 Million bp) nuclear phylogeny of the Delphininae. Phylogenetic resolution of this group has been especially intractable, likely because it has experienced a recent species radiation. We carried out cross-lineage reticulation analyses, and tested for several sources of potential bias in determining phylogenies from genome sampling data. We assessed the divergence time and historical demography of T. truncatus and T. aduncus by sequencing the T. aduncus genome and comparing it with the T. truncatus reference genome. Our results suggest monophyly for the genus Tursiops, with the recently proposed T. australis species falling within the T. aduncus lineage. We also show the presence of extensive cross-lineage gene flow between pelagic and European coastal ecotypes of T. truncatus, as well as in the early stages of diversification between spotted (Stenella frontalis; Stenella attenuata), spinner (Stenella longirostris), striped (Stenella coeruleoalba), common (Delphinus delphis), and Fraser's (Lagenodelphis hosei) dolphins. Our study suggests that cross-lineage gene flow in this group has been more extensive and complex than previously thought. In the context of biogeography and local habitat dependence, these results improve our understanding of the evolutionary processes determining the history of this lineage.

Similar bacterial communities on healthy and injured skin of black tip reef sharks.

BACKGROUND: Sharks are in severe global decline due to human exploitation. The additional concern of emerging diseases for this ancient group of fish, however, remains poorly understood. While wild-caught and captive sharks may be susceptible to bacterial and transmissible diseases, recent reports suggest that shark skin may harbor properties that prevent infection, such as a specialized ultrastructure or innate immune properties, possibly related to associated microbial assemblages. To assess whether bacterial community composition differs between visibly healthy and insulted (injured) shark skin, we compared bacterial assemblages of skin covering the gills and the back from 44 wild-caught black-tip reef sharks (Carcharhinus melanopterus) from the Amirante Islands (Seychelles) via 16S rRNA gene amplicon sequencing. RESULTS: Shark skin-associated bacterial communities were diverse (5971 bacterial taxa from 375 families) and dominated by three families of the phylum Proteobacteria typical of marine organisms and environments (Rhodobacteraceae, Alteromonadaceae, Halomonadaceae). Significant differences in bacterial community composition of skin were observed for sharks collected from different sites, but not between healthy or injured skin samples or skin type (gills vs. back). The core microbiome (defined as bacterial taxa present in ≥50% of all samples) consisted of 12 bacterial taxa, which are commonly observed in marine organisms, some of which may be associated with animal host health. CONCLUSION: The conserved bacterial community composition of healthy and injured shark skin samples suggests absence of severe bacterial infections or substantial pathogen propagation upon skin insult. While a mild bacterial infection may have gone undetected, the overall conserved bacterial community implies that bacterial function(s) may be maintained in injured skin. At present, the contribution of bacteria, besides intrinsic animal host factors, to counter skin infection and support rapid wound healing in sharks are unknown. This represents clear knowledge gaps that should be addressed in future work, e.g. by screening for antimicrobial properties of skin-associated bacterial isolates.

Use of Photo-Identification and Mark-Recapture Methodology to Assess Basking Shark (Cetorhinus maximus) Populations.

Following centuries of exploitation, basking sharks (Cetorhinus maximus) are considered by IUCN as Endangered in the Northeast Atlantic, where they have now been substantially protected for over two decades. However, the present size of this population remains unknown. We investigated the use of photo-identification of individuals' dorsal fins, combined with mark-recapture methodology, to investigate the size of populations of basking shark within the west coast of Scotland. From a total of 921 encounters photographed between 2004 and 2011, 710 sharks were found to be individually identifiable based on dorsal fin damage and natural features. Of these, only 41 individuals were re-sighted, most commonly both within days of, and close to the site of, the initial encounter. A smaller number were re-sighted after longer periods of up to two years. A comparison of the distinguishing features of individuals on first recording and subsequent re-sighting showed that in almost all cases these features remained little changed, suggesting the low re-sighting rate was not due to a loss of distinguishing features. Because of the low number of re-sighting we were not able to produce reliable estimates for the long-term regional population. However, for one 50 km diameter study area between the islands of Mull, Coll and Tiree, we were able to generate closed-population estimates for 6-9 day periods in 2010 of 985 (95% CI = 494-1683), and in 2011 of 201 (95% CI = 143-340). For the same 2011 period an open-population model generated a similar estimate of 213 (95% CI = 111-317). Otherwise the low rate and temporal patterning of re-sightings support the view that such local basking shark populations are temporary, dynamic groupings of individuals drawn from a much larger regional population than previously supposed. The study demonstrated the feasibility and limitations of photo-identification as a non-invasive technique for identifying individual basking sharks.

Sharks and people: insight into the global practices of tourism operators and their attitudes to shark behaviour.

Shark tourism is a popular but controversial activity. We obtained insights into this industry via a global e-mailed questionnaire completed by 45 diving/snorkelling operators who advertised shark experiences (shark operators) and 49 who did not (non-shark operators). 42% of shark operators used an attractant to lure sharks and 93% stated they had a formal code of conduct which 86% enforced "very strictly". While sharks were reported to normally ignore people, 9 operators had experienced troublesome behaviour from them. Whilst our research corroborates previous studies indicating minimal risk to humans from most shark encounters, a precautionary approach to provisioning is required to avoid potential ecological and societal effects of shark tourism. Codes of conduct should always stipulate acceptable diver behaviour and appropriate diver numbers and shark operators should have a moral responsibility to educate their customers about the need for shark conservation.

Refinements in husbandry, care and common procedures for non-human primates: Ninth report of the BVAAWF/FRAME/RSPCA/UFAW Joint Working Group on Refinement.

Preface Whenever animals are used in research, minimizing pain and distress and promoting good welfare should be as important an objective as achieving the experimental results. This is important for humanitarian reasons, for good science, for economic reasons and in order to satisfy the broad legal principles in international legislation. It is possible to refine both husbandry and procedures to minimize suffering and improve welfare in a number of ways, and this can be greatly facilitated by ensuring that up-to-date information is readily available. The need to provide such information led the British Veterinary Association Animal Welfare Foundation (BVAAWF), the Fund for the Replacement of Animals in Medical Experiments (FRAME), the Royal Society for the Prevention of Cruelty to Animals (RSPCA) and the Universities Federation for Animal Welfare (UFAW) to establish a Joint Working Group on Refinement (JWGR) in the UK. The chair is Professor David Morton and the secretariat is provided by the RSPCA. This report is the ninth in the JWGR series. The RSPCA is opposed to the use of animals in experiments that cause pain, suffering, distress or lasting harm and together with FRAME has particular concerns about the continued use of non-human primates. The replacement of primate experiments is a primary goal for the RSPCA and FRAME. However, both organizations share with others in the Working Group, the common aim of replacing primate experiments wherever possible, reducing suffering and improving welfare while primate use continues. The reports of the refinement workshops are intended to help achieve these aims. This report produced by the British Veterinary Association Animal Welfare Foundation (BVAAWF)/Fund for the Replacement of Animals in Medical Experiments (FRAME)/Royal Society for the Prevention of Cruelty to Animals (RSPCA)/Universities Federation for Animal Welfare (UFAW) Joint Working Group on Refinement (JWGR) sets out practical guidance on refining the husbandry and care of non-human primates (hereinafter primates) and on minimizing the adverse effects of some common procedures. It provides a valuable resource to help understand the physical, social and behavioural characteristics and needs of individual primates, and is intended to develop and complement the existing literature and legislative guidelines. Topics covered include refinements in housing, husbandry and common procedures such as restraint, identification and sampling, with comprehensive advice on issues such as primate communication, assessing and facilitating primate wellbeing, establishing and maintaining social groups, environmental and nutritional enrichment and animal passports. The most commonly used species are the key focus of this resource, but its information and recommendations are generally applicable to other species, provided that relevant individual species characteristics are taken into account.

Transatlantic migration and deep mid-ocean diving by basking shark.

Despite being the second largest fish, basking sharks (Cetorhinus maximus) have been assumed to remain in discrete populations. Their known distribution encompasses temperate continental shelf areas, yet until now there has been no evidence for migration across oceans or between hemispheres. Here we present results on the tracks and behaviour of two basking sharks tagged off the British Isles, one of which released its tag off Newfoundland, Canada. During the shark's transit of the North Atlantic, she travelled a horizontal distance of 9589 km and reached a record depth of 1264 m. This result provides the first evidence for a link between European and American populations and indicates that basking sharks make use of deep-water habitats beyond the shelf edge.

Lipid composition, fatty acid profiles, and lipid-soluble antioxidants of eggs of the Hermann's tortoise (Testudo hermanni boettgeri).

The major lipid classes, their fatty acid profiles, and the amounts of the lipid-soluble components, vitamin E, vitamin A, and carotenoids, were determined for egg yolks of the Hermann's tortoise (Testudo hermanni boettgeri) with the aim of identifying any features that may potentially impair the adaptation of this endangered species to deteriorations in habitat. Total lipid formed 16% (wt/wt) of the fresh yolk and consisted of (wt/wt) 74.4% triacylglycerol, 18.1% phospholipid, 3.0% cholesteryl ester, and 3.4% free cholesterol. Despite a diet based on green plants, contributing alpha-linolenic acid as the main polyunsaturate, this fatty acid formed only 3.8% of the total mass of fatty acid of the total lipid. The main acyl component of the yolk lipids was the monounsaturated fatty acid, oleic acid, which formed 45.6% of the total. The most striking feature of the yolk composition was the almost complete lack of two nutrients, docosahexaenoic acid and vitamin A, which are essential for the developing embryo. Although it is feasible that the embryo synthesizes docosahexaenoic acid from yolk-derived alpha-linolenic acid and also converts yolk-derived beta-carotene to vitamin A, the yolk is poorly endowed with both these precursors. The stringencies displayed by the yolk composition in this species may limit the flexibility to adapt to changes in the availability of food items when the habitat is threatened. Zoo Biol 20:75-87, 2001. Copyright 2001 Wiley-Liss, Inc.