The use of machine learning to detect foraging behaviour in whale sharks: a new tool in conservation.

In this study we present the first attempt at modelling the feeding behaviour of whale sharks using a machine learning analytical method. A total of eight sharks were monitored with tri-axial accelerometers and their foraging behaviours were visually observed. Our results highlight that the random forest model is a valid and robust approach to predict the feeding behaviour of the whale shark. In conclusion this novel approach exposes the practicality of this method to serve as a conservation tool and the capability it offers in monitoring potential disturbances of the species.

Fisheries interactions and the challenges for target and nontargeted take on shark conservation in the Mexican Pacific.

Sharks have been of great cultural and socioeconomic importance in Mexico since the late 19th century, when the first fisheries were prosecuted in the Gulf of California to export fins to China. Mexican shark and ray fisheries are classified mainly by the size of the fishing vessel and include small- (7.5-10m), medium- (10-27m), and large-sized (>27m) fisheries. All are multispecies fisheries that use longline or gillnet gear, with their relative productivity varying over time. Off the Pacific coast, early shark small size vessel fisheries in the Gulf of California were driven by the need for vitamin A from livers, especially during World War II. As this fishery declined, new shark fishing opportunities arose because of government support and the development of the medium-sized fishery, which was capable of farther offshore excursions. Shark meat became an important part of the diets of poor and impoverished citizens during the 1950s and 1960s. The establishment of a Mexican Exclusive Economic Zone in 1976 pushed foreign vessels from Asia out of Mexican waters and led to the development of the large-sized vessel fishery to exploit pelagic sharks in offshore waters. By the early 1980s, Mexico shark fisheries were among the most productive in the world; however, a national economic crisis reduced effort and landings until the late 1980s, when several new fisheries emerged. Landings from Pacific states fluctuated between ~13,000 and 24,000t (dressed weight) during 1987-2012 but expanded steadily thereafter because of government support and offshore fleet expansion. Shark fisheries landings from the Mexican Pacific are currently at their highest recorded levels, exceeding 31,000t; however, a lack of species-specific landings and life history information has precluded population assessments of targeted stocks. In addition, though several recent management measures have been enacted to protect Mexican shark and ray fishery resources, the enforcement of these regulations is severely lacking. Therefore, the long-term sustainability of current fishing levels is unknown but should engender concern based on anecdotal evidence of serial depletion among historical elasmobranch targets in the Mexican Pacific.

Shark ecotourism in Mexico: Scientific research, conservation, and contribution to a Blue Economy.

Shark ecotourism has the potential to contribute significantly to local and national economies and conservation, though this depends on a concerted effort to implement evidence-based management. Sharks are key attractions at some of the most important marine ecotourism sites throughout Mexico, focusing particularly on whale sharks, white sharks, hammerhead sharks, and several other reef-associated and pelagic species. This generates important employment opportunities and millions of USD in revenue, but truly implementing ecotourism requires that education and conservation be a part of activities and that these benefit local communities, so that the industry can be socially, economically and ecologically sustainable. In Mexico, this includes addressing potential negative impacts from vessel overcrowding, provisioning, inequitable distribution of ecotourism and conservation benefits and costs, and a broader lack of governance capacity to ensure that coastal development is environmentally sustainable and socially equitable. In the context of a Blue Economy centred on sustainability and local benefits, ecotourism provides a key incentive and opportunity to improve ocean management.

Introduction: The sharks of Pacific Mexico and their conservation: Why should we care?

Sharks exhibit a broad range of body forms, occupy diverse ecological niches, and are found in every ocean on earth. They have roles as both predator and prey and have an evolutionary history far longer than that of human beings. As long as humans have interacted with the ocean they have interacted with sharks and, as a result, sharks have featured in the mythology, history, and fisheries of diverse cultures around the world. Only in the last 100 years or less, however, have humans begun to study and fully realize the susceptibility of these animals to intensive fishing pressure, ecological degradation, and other anthropogenic factors. This volume highlights the biodiversity and biological attributes of, and conservation efforts targeted at, populations of sharks that reside in the Northeast Pacific Ocean (NEP) bordering the west coast of Mexico. Together with a pair of companion volumes published in 2017 that focused on the NEP adjacent to the United States and Canada, this volume provide readers a detailed backdrop of shark biology and conservation in the Mexican waters of the Northeast Pacific against which to consider their own actions, and those of resource managers, academics, and educators, as they relate to the long-term conservation of sharks and their relatives.

Two decades of genetic profiling yields first evidence of natal philopatry and long-term fidelity to parturition sites in sharks.

Sharks are a globally threatened group of marine fishes that often breed in their natal region of origin. There has even been speculation that female sharks return to their exact birthplace to breed ('natal philopatry'), which would have important conservation implications. Genetic profiling of lemon sharks (Negaprion brevirostris) from 20 consecutive cohorts (1993-2012) at Bimini, Bahamas, showed that certain females faithfully gave birth at this site for nearly two decades. At least six females born in the 1993-1997 cohorts returned to give birth 14-17 years later, providing the first direct evidence of natal philopatry in the chondrichthyans. Long-term fidelity to specific nursery sites coupled with natal philopatry highlights the merits of emerging spatial and local conservation efforts for these threatened predators.

Populations analysis of the Brazilian Sharpnose Shark Rhizoprionodon lalandii (Chondrichthyes: Carcharhinidae) on the São Paulo coast, Southern Brazil: inferences from mt DNA sequences

Sharks of the genus Rhizoprionodon can be considered some of the most important predators along the trophic coastal marine ecosystems and represent an important economic resource for the small-scale fisheries, especially on the Brazilian coastline. In order to analyze the population structure of the shark Rhizoprionodon lalandii of São Paulo, Southeastern coast of Brazil, levels of genetic diversity were identified by nucleotide sequence analyses of the mitochondrial DNA control region. The results obtained from this study present moderate values of haplotype diversity and low nucleotide diversity. Although the AMOVA tests (ΦST = 0.08394, P < 0.01) had shown slightly differences among the studied samples, evidence for the occurrence of population structuring was not found, which may be a general feature of sharks living in coastal areas.

Tubarões do gênero Rhizoprionodon são considerados predadores de grande importância ao longo da cadeia trófica nos ecossistemas costeiros e marinhos, também representando um importante recurso econômico para a pesca, especialmente no litoral brasileiro. A fim de analisar a estrutura populacional do tubarão Rhizoprionodon lalandii no litoral de São Paulo, sudeste do Brasil, foram identificados os níveis de diversidade genética a partir da análise de sequências nucleotídicas da região controladora do DNA mitocondrial. Os dados obtidos neste estudo apresentam valores moderados de diversidade haplotípica e baixos índices de diversidade nucleotídica. Embora os testes de AMOVA (ΦST = 0,08394, P < 0,01) tenham revelado uma pequena diferença entre as amostras estudadas, evidências sobre a ocorrência de estruturação populacional não foram encontradas o que pode representar uma característica geral para tubarões vivendo em áreas costeiras.