Citizen science: Diving

Sightment by recreational divers

Citizen science: Sightment by recreational divers

Long-term sightings of elasmobranchs by recreational divers in the island of Gran Canaria (Central-East Atlantic)) The dive centre Davy Jones Diving collected a 6-year series of sightings data in the area of El Cabrón (Gran Canaria). The results give an important insight in the seasonality of the 9 species of elasmobranchs which were registered in the area. Read the poster presented during the conference IV Congreso de Ciencias del Mar.

Strong seasonality of the angel shark

The observations of the common angelshark (Squatina squatina) showed a strong seasonality over the 6-year study period. The minimum average probability to observe the species occurs when the water temperature reached its maximum, or is above 22˚C, with only one observation in 50 dives (2%). When the water temperature was cold or temperate, between 18˚ to 21˚C, there was a maximum average probability to encounter an individual with up to one observation in 3.6 dives (27.5%).

Citizen science ElasmoCan: Sightings of the angelshark (Squatina squatina) by divers in El Cabrón (Gran Canaria)

The angelshark is the most frequent observed species

At least one of the in total 9 reported elasmobranch species can be observed year round in the area of “El Cabrón” (Gran Canaria). The common angelshark or monkfish Squatina squatina was the only reported shark species and the most frequent observed species of all, with a total of 43.5% of the sightings. The common stingray Dasyatis pastinaca was the second most observed species with 22.5% of the observations, followed by the fantail stingray ray Taeniurops grabata, 15.6%, the eagle ray Myliobatis Aquila, 8.6%, the marbled electric ray Torpedo marmorata, 6.3%, the spiny butterfly ray Gymnura altavela, 2.3%, the bull ray Aetomylaeus bovinus, 0.7%, the rough tailed ray Dasyatis centroura, 0.3%, and the devil ray Mobula sp., 0.1%, which was very rarely observed.

Citizen science ElasmoCan: Sighting of the elasmobranch species in El Cabrón (Gran Canaria).

More information about citizen science

Read more information about earlier citizen science studies with recreational divers in the Canary Islands and how dive centers can contribute to research in the section Research lines.

(*) Species names follow Weigmann S (2016) Annotated checklist of the living sharks, batoids and chimaeras (Chondrichthyes) of the world, with a focus on biogeographical diversity. J Fish Biol 88: 837-1037. doi: 10.1111/jfb.12874