Despite it being the beginning of August — the warmest month in the Amvrakikos Gulf in Greece — night-time on the boat is chilly. Fishers, on the hunt for striped prawns (Penaeus kerathurus), haul in nets in which sharks and rays occasionally appear among the catch. These unintended captives are of interest to onboard marine scientist Roxani Naasan Aga-Spyridopoulou, who studies and records them for By ElasmoCatch, a conservation project led by the Greek environmental organization iSea.

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To Naasan Aga-Spyridopoulou, the gulf is like “a smaller Mediterranean within the Mediterranean”, a hotspot for species diversity. Located around 250 kilometres north-west of Athens, the gulf is formed by the Ionian Sea and the estuaries of two rivers. The flow of fresh water into seawater and the unusual circulation patterns this creates foster biodiversity. Around 300 professional small-scale fishers work in the area, and more than half of them participate in the By ElasmoCatch project, allowing scientists to come on board their boats to collect data on shark and ray species — referred to collectively as elasmobranches.

In the early morning, as the Sun rises from behind steep hills surrounding the gulf, Naasan Aga-Spyridopoulou carefully lifts the elasmobranches buried between prawns from the net. The By ElasmoCatch project aims to investigate how these species are affected when they are caught accidentally, as well as the best approaches to ensure their survival. First, Naasan Aga-Spyridopoulou evaluates the short-term survival rates of individuals after capture, placing them in a tank of oxygenated water for 40 minutes and scoring their health and movements. “The results show that when handling is done correctly, the short-term survival rate is very high — for some species, over 95%,” she explains.

A fisher hauls in a net, as a common smooth-hound shark (Mustelus mustelus) is inspected.

A series of images showing Roxani holding and inspecting a common smooth-hound ray, pointing it to an umbilical scar on the shark’s belly while holding it, and looking at two small sharks inside a transparent plastic container ready to be oxygenated., image

Naasan Aga-Spyridopoulou points to an umbilical scar, which indicates this shark was born in the past year.

Two common smooth-hound sharks are transferred to an oxygenated tank after their capture.

Naasan Aga-Spyridopoulou then measures the animals’ size and weight, and, if possible, determines their sex and maturity. Finally, the animals are tagged with a dart tag carrying a unique code and a telephone number that fishers and the public can use to report sightings. So far, at least 361 animals have been tagged and released over a four-year period. “When I disentangle a shark or a ray from the nets I feel both responsibility and awe. Its survival depends on careful handling,” says Naasan Aga-Spyridopoulou. “At release, I feel I have done what I can and life will take its course.” Early results from the study are promising: there has been a relatively high recapture rate, especially for the common smooth-hound shark (Mustelus mustelus), which suggests good long-term survival rates.

A series of images showing Roxani standing on the boat holding a piece of polystyrene with a light on top, with hills in the background at sunset, and her handing over it to a fisherman who is accompanying her., image

Before the start of this project in 2022, information about the region’s elasmobranches had been based mainly on anecdotes, with confirmed sightings of only two species 1, 2. Now, ten species have been documented3, a considerable amount of diversity for a gulf that only covers about 400 square kilometres. Two of these species — the common eagle ray (Myliobatis aquila) and the bull ray (Aetomylaeus bovinus) — are listed as critically endangered by the International Union for Conservation of Nature (IUCN). “Until recently, nobody knew this gulf was a nursery for sharks and rays,” Naasan Aga-Spyridopoulou says.

Naasan Aga-Spyridopoulou disentangles a spiny butterfly ray (Gymnura altavela) from a fishing net aboard one of the boats.

A series of images showing Roxani's hands on the boat disentangling a spiny butterfly ray from a net, handling the tangled net on a ray's tail with a pile of nets in the background, checking Spiny butterfly ray (Gymnura altavela) conditions inside a transparent plastic container, measuring the ray with a yellow measuring tape against a tiled background and tagging the ray before releasing it in the water., image

A marbled ray (Dasyatis marmorata) is found in a catch.

A spiny butterfly ray is transferred to an oxygenated tank, where its condition is monitored for 40 minutes.

Naasan Aga-Spyridopoulou measures the ray before it is released, collecting data such as size, weight and sex.

Some of the elasmobranches, including this Tortonese’s ray (Dasyatis tortonesei), are tagged before they are released to hel

Saving sharks and rays one catch at a time — in photos