This study describes the genetic diversity and level of genetic differentiation of the scalloped hammerhead shark Sphyrna lewini from eight putative nursery areas in the Mexican Pacific Ocean, using the mtDNA control region. Genetic analyses revealed a particular spatial divergence between La Reforma and all the remaining sites, with five exclusive haplotypes and the highest genetic diversity. This pattern may be interpreted as the signature of regional female philopatry, relatively to a particular female-mediated gene flow for La Reforma, which shows a strong subdivision in the Gulf of California.
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http://dx.doi.org/10.1111/jfb.15227 | DOI Listing |
Mar Pollut Bull
April 2024
Department of Earth and Environmental Sciences (DISAT), University of Milano-Bicocca, Piazza Della Scienza 1, 20126 Milan, Italy; MaRHE Center (Marine Research and High Education Center), Magoodhoo Island, Faafu Atoll 12030, Maldives.
Sharks are particularly susceptible to bioaccumulation due to their life history characteristics and trophic position within marine ecosystems. Despite this, studies of bioaccumulation cover only a small proportion of extant species. In this study we report concentrations of trace elements and heavy metals in blood samples of Sphyrna lewini for the first time.
View Article and Find Full Text PDFBiodivers Data J
March 2023
Galapagos Whale Shark Project, Puerto Ayora, Ecuador Galapagos Whale Shark Project Puerto Ayora Ecuador.
Whale sharks frequently appear to interact or associate with other species, which vary depending on the community structure and the demographic of the whale sharks at each location globally. Here, we present the species sighted frequently around whale sharks in the Galapagos Archipelago and reported by dive guides and scientists and also in earlier publications. These associated species include cetacean species: bottlenose dolphins , other shark species: silky sharks , Galapagos sharks , scalloped hammerhead sharks , tiger sharks and teleost fish species: remoras remora, yellowfin tuna , almaco jacks and black jacks .
View Article and Find Full Text PDFSci Total Environ
January 2024
Instituto Politécnico Nacional, Centro Interdisciplinario de Ciencias Marinas, Av. IPN s/n. La Paz, Baja California Sur C. P. 23096, Mexico.
Organochlorine compounds (OCs), such as organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs), remain ubiquitous in marine ecosystems despite their prohibition or restriction, posing a risk to marine wildlife and humans. Their accumulation in liver tissue and potential toxicity in three exploited shark species (the scalloped hammerhead, Sphyrna lewini; the Pacific sharpnose shark, Rhizoprionodon longurio; and the Pacific angel shark, Squatina californica) with different physiological and ecological features from the western Gulf of California (GC) were investigated. Forty of the 47 OCs analyzed were identified, evidencing a greater agricultural than industrial influence considering the high DDTs/PCBs ratios.
View Article and Find Full Text PDFJ Fish Biol
August 2023
Leigh Marine Research Laboratory, Institute of Marine Science, University of Auckland, Auckland, New Zealand.
Sharks (elasmobranchs) are an ancient, diverse group of fishes, representing a basal stage in the evolution of vertebrate hearing. Yet, our understanding of behavioural measures of hearing abilities in sharks is limited. To address this, an operant conditioning paradigm was designed, and scalloped hammerhead Sphyrna lewini and rig (spotted estuary smooth hound) Mustelus lenticulatus were successfully trained to respond to pure-tone acoustic stimuli from an underwater speaker.
View Article and Find Full Text PDFScience
May 2023
Hawai'i Institute of Marine Biology, University of Hawai'i at Mānoa, Kāne'ohe, HI 96744, USA.
Fish moving between different thermal environments experience heat exchange via conduction through the body wall and convection from blood flow across the gills. We report a strategy of preventing convective heat loss at the gills during excursions into deep, cold water by the tropical scalloped hammerhead shark (). Adult scalloped hammerhead sharks dive rapidly and repeatedly from warm (~26°C) surface waters to depths exceeding 800 meters with temperatures as low as 5°C.
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