So I asked leading shark ethologist and behaviourist, Professor Samuel 'doc' Gruber to elaborate. After pointing out how much pain women feel when they give birth, making the point that suffering has no effect on reproduction, he reminded me that sharks evolved their mating behaviours and the physical structures involved, separately from other animals.
As fans of crime series will know, every living creature sheds DNA through skin cells, hair, scales and other bodily secretions as they move. This leaves behind a trace in whatever environment they were in, thus becoming environmental DNA (eDNA).
An emerging molecular technique called eDNA analysis enables researchers to scan samples of water, air, or soil for tiny remnants of DNA and identify organisms it came from.
Genomic data reveals historical population declines and high levels of inbreeding in great hammerhead.
In a recent report by the IUCN Red List of Threatened Species, 31 percent of all shark species are threatened (Critically Endangered, Endangered or Vulnerable). In 1980, only 9 species of oceanic sharks and rays were listed as threatened.
What do sharks do when we’re not looking?
To answer this question, Murdoch University fish biologist Lauran Brewster attached accelerometers to the fins of 24 lemon sharks in the Bimini Islands, Bahamas to find out.
Shark dives provide an excellent way to meet a lot of sharks, and represent a unique situation in which sharks are treated well by humanity.
Shark dive clubs usually bring some fishy scraps—in most cases the remains left over after big fish have been cut up for sale. The scent attracts the sharks into view, and provides a bit of excitement as the animals investigate and try to get a piece.
The shark and ray population in the north Atlantic are in recovery, according to a recent study published in the Proceedings of the National Academy of Sciences (PNAS) journal.
Lead author Nathan Pacoureau, postdoctoral research fellow at Simon Fraser University (SFU), and his team came to this conclusion after analyzing trends in fishing pressure, fisheries management and population status for wide-ranging coastal sharks and rays in the western Atlantic Ocean.
Sand tiger sharks, top predators that live in coastal waters off the Eastern United States, have experienced drastic population declines over the past several decades. Understanding how these sharks move and interact could help biologists better conserve this species and determine how vulnerable they are to human activities. During summer, the sharks congregate in the shallow waters of Delaware Bay but are highly migratory, travelling as far south as the Carolinas and Florida during the winter and early spring.
Sharks elicit strong emotions, be it the thrill of a planned encounter underwater or fear propelled by social media and lack of information. Of the more than 400 species of sharks, it is the small family of mackerel sharks that is most iconic. These sharks prompted me to share why one of them, the salmon shark, is an especially remarkable species.
This action expands on the 2022 closure of the Guadalupe Island Biosphere Reserve by the National Commission of Natural Protected Areas (CONANP), the federal agency tasked with managing Mexico’s protected natural areas.
They also closed the island to cage diving in 2021 and the pandemic closed down operations in 2020.
Scientists with the New England Aquarium found that nurse sharks, Ginglymostoma cirratum, returned to the waters off the Dry Tortugas, 70 miles (113km) from Key West, to mate for up to 28 years. The Dry Tortugas has been known as a courtship and mating site for nurse sharks since 1895.
A 30-year (1992–2021) study documented long-term site fidelity to this area, with data from 137 adult sharks.
It certainly looks “prehistoric”—whatever that means. Cigar-shaped, blunt-snouted, with that slightly “sock-puppet-looking” smirk, the overall look of this big beastie is very much that of an ancestral shark, like some of the deep-water dogfishes, the sleeper sharks and others. Indeed, fossil remains similar to modern sevengills and sixgills are known from the Jurassic and perhaps much earlier.
