Pacific angelshark - Squatina californica

The Pacific angelsharks Squatina californica is a strongly flattened bottom shark that superficially resembles a ray with its broad pectoral and pelvic fins. Taxonomically leads WoRMS the species within the Squalomorphi, the order Squatiniformes, the family Squatinidae and the genus Squatina.

Important for differentiating it from rays: The gill slits are on the sides of the head, the large pectoral fins are not completely fused to the head, and the mouth is located at the front of the snout. Eyes and spray holes are on top so that the animal can breathe while half-buried and observe its surroundings.

Identifying features

• Broad, flat forebody with very large, angled pectoral fins.
• Gray to brownish upper surface with many small dark spots; Underside significantly lighter.
• A pair of conical barbels on the snout and a wide terminal mouth opening.
• Two small dorsal fins are located far back on the body; an anal fin is missing.
• Juveniles may have more noticeable rows of thorns, while adults appear smoother.

Shark-References gives the German name Pacific angelshark and documents the first description by Ayres in 1859. The head, barbels, fin shape, spot markings and tail base are particularly helpful for field photos.

The Pacific angelsharks lives in the eastern Pacific. The German country assignments in the species profile refer to Canada, the USA and Mexico; The species is particularly well known from Californian and Baja-Californian coastal waters.

FishBase summarizes the wide, but taxonomically not everywhere simple, distribution from Canada to the Gulf of California and further south in the eastern Pacific. In practice, finds north of California are significantly rarer than in the warm-temperate core area.

Sand flats, kelp and reef edges

Typical habitats include shallow coastal areas with sandy or mud bottoms, bays, estuaries, kelp forests, rocky edges and heads of underwater canyons. The species profile states 0 to 100 m; Literature data range from very shallow to much deeper shelf areas.

What is crucial for divers is that the shark often lies almost invisibly in the sediment. Good sightings are more likely to occur where soft ground directly borders reef or kelp structures and small fish regularly swim within reach of the hidden predator.

Loud Florida Museum is Squatina californica a benthic predator that burrows in sand or mud during the day and becomes more active at night. Camouflage is part of the hunting strategy: the shark waits until prey swims close enough and then explosively snaps forward.

food and hunting

The diet mainly includes bottom-dwelling bony fish, including umberfish, flatfish, reef and kelp forest species, as well as squid and occasionally crustaceans. The attack is short and very fast: the mouth creates a suction effect when it opens, while the jaws snap forward.

The animals can use the same successful hide during the day and move to new areas at night. Such small-scale movements make the species well-adapted locally, but also sensitive to fishing pressure in individual bays or island areas.

Reproduction

Reproduction is aplacental viviparous. Romero-Caicedo et al. 2016 describes data from La Paz Bay in the Gulf of California: Females became larger and heavier than males, and the study shows a distinct spatial and sexual structure of mature animals.

Litters of a few to a dozen young animals are generally mentioned. Young animals are born fully developed and use flatter, protected habitats. As with many ground sharks, late maturity means heavy local withdrawals are slow to offset.

The IUCN Red List classifies the Pacific angelshark globally as potentially at risk a. The protection status varies from region to region: Californian stocks benefit from strong net restrictions, while fishing pressure in parts of Mexico and the taxonomic delimitation of southern stocks need to be further monitored.

The California Marine Species Report describes historical overfishing in California particularly clearly: landings rose sharply in the 1980s, then plummeted; Later bans on coastal nets protected large parts of the primary habitat.

Main hazards

• Targeted catch and bycatch in gillnets, bottom trawls and small-scale coastal fisheries.
• Strong local loyalty, which means that individual stocks can quickly suffer from regional fishing pressure.
• Used as a food fish, marketed as, among other things, angel shark or monkfish.
• Unclear species boundaries in the Gulf of California and the southeastern Pacific make population assessment difficult.
• Dependence on intact sandy, muddy and reef bottom habitats.

Effective protection therefore requires spatially appropriate fishing rules, observer data, accurate species identification and caution when reopening historical fisheries. Especially in the case of angel sharks, one population can appear locally stable, while neighboring groups are already heavily stressed.

To humans, the Pacific angelsharks is not typically an aggressive shark. It becomes dangerous when a resting animal is touched, pulled by the tail, harassed while spearfishing or treated as catch on board. The shark can then snap up or sideways very quickly.

Animal Diversity Web also describes the species with names such as monk fish or sand devil and refers to its proximity to coastal fishing and human use. It is precisely this dual role that is typical: a fascinating camouflage artist for divers, and historically an exploitable ground shark for fisheries.

Behavior while diving

• Do not kneel or reach on sandy areas where an angel shark might be lying there.
• Do not expose a resting animal, illuminate it until it flees, or harass it for photos.
• Keep your distance to the sides and do not put your hands in front of your mouth, head or prey.
• Document sightings with location, depth, habitat and photo without moving the animal.

For shark diving, the Pacific angelsharks is a good example of how encounters do not always consist of large open water sharks. Sometimes the most exciting species lies directly on the ground, perfectly camouflaged, and above all requires calm fin technique and respect for the habitat.