Angel sharks are a distinctive group of sharks with a flattened body shape, resembling rays or skates, but are indeed sharks belonging to the family Squatinidae. Found primarily in coastal waters, these creatures are ambush predators, often burying themselves in sand or mud. Their specialized appearance and behavior contribute to their role in marine ecosystems, but also make them vulnerable to external pressures. Many angel shark species face a severe risk of extinction, with several classified as critically endangered.
Unique Biological Traits and Vulnerabilities
Angel sharks exhibit a bottom-dwelling lifestyle, preferring sandy or muddy seafloors where they camouflage themselves. This allows them to lie in wait, concealed from prey, striking rapidly. However, this behavior, which aids their hunting, also makes them highly vulnerable to fishing gear that operates along the seabed.
Their camouflage, while effective for ambushing prey, offers little protection against bottom-contact fishing methods, as they are difficult to detect and avoid. Angel sharks also grow slowly, reach sexual maturity at a later age, and produce a relatively small number of offspring, typically 7 to 25 pups per litter. This low reproductive output means their populations recover very slowly from declines, making them especially susceptible to pressures that reduce their numbers.
Overarching Threats from Human Activities
The most significant threat to angel shark populations stems from commercial fishing practices, especially bycatch. Bottom trawling, a method involving dragging large nets across the seafloor, is especially damaging due to the sharks’ bottom-dwelling nature, leading to unintentional capture. Other fishing methods like gillnetting and longlining also contribute to their accidental capture, further depleting their numbers. Historically, some angel shark species were even targeted directly by fisheries, further exacerbating their decline.
Habitat degradation and loss also pose a substantial threat to angel sharks. Coastal development, pollution, and dredging activities damage their nursery and feeding grounds in shallow coastal waters, estuaries, and seagrass beds. These disruptions reduce suitable habitat, impacting their ability to feed and reproduce. Emerging concerns include the potential impacts of climate change, such as ocean warming and acidification, which can alter their habitats and affect prey availability. For instance, rising ocean temperatures can disrupt mating behaviors, with female angel sharks avoiding traditional breeding grounds when waters become too warm, potentially leading to reproductive failure.
Conservation Status and Protective Frameworks
Many angel shark species are classified as Critically Endangered on the International Union for Conservation of Nature (IUCN) Red List of Threatened Species. This classification reflects severe population declines, estimated to be over 80% for some species in the last 45 years. For example, the common angelshark (Squatina squatina), once widespread in the Atlantic and Mediterranean, is now considered critically endangered.
Their conservation status has led to their inclusion in international agreements like the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES). CITES Appendix II listing aims to ensure that any international trade is both legal and sustainable. Regional conservation efforts, such as the Mediterranean Angel Sharks: Regional Action Plan, have been developed to address regional threats. These frameworks outline objectives to minimize fishing-related mortality, protect habitats, and establish national legislation to safeguard angel sharks.