Trauma linked to fishing nets and accidental capture of the torpedo ray

What is it?

The torpedo ray (Torpedo torpedo and Torpedo marmorata) is a cartilaginous fish capable of producing an electric discharge, present particularly along the Tunisian coasts. Like many marine species living near the bottom, it is frequently accidentally captured by fishing nets (trawls, gillnets, longlines) or injured during handling by fishermen. These events do not constitute a “disease” in the classic sense but a set of physical traumas and stress that can seriously compromise the survival of the animal.\n\nThis sheet describes the lesions and complications observed in a torpedo ray victim of accidental capture (“bycatch” or bycatch) or injured by fishing gear.

Signs depend on the type of trauma suffered.\n\nWe may observe wounds or lacerations on the skin, fins (wings) or tail, caused by friction in the mesh of the net or by hooks.\n\nLocalized swelling or deformation of a fin may indicate a fracture of the cartilaginous skeleton or dislocation.\n\nThe animal captured and released may present a abnormal swimming: difficulty remaining horizontal, swimming in a circle, or inability to return to the bottom.\n\nSignificant stress linked to capture (leaving the water, handling, pressure variations) can result in very rapid breathing at the level of the vents (respiratory orifices), prolonged lethargy or an inability to take refuge after returning to the water.\n\nIn the most serious cases, the animal may die quickly after capture, sometimes without visible lesion, due to cumulative physiological stress (barotrauma, exhaustion, exposure to air).

The causes are exclusively of mechanical and environmental origin, linked to fishing activity: \n\n- Entanglement in a gill net, a bottom trawl or a longline, leading to compression, abrasion or tearing of tissues.\n- Capture by hook, causing a puncture wound in the mouth or digestive tract.\n- Brutal handling by fishermen during sorting of the catch (the animal often being quickly rejected due to the risk of electric shock).\n- Prolonged exposure to air outside the water, leading to hypoxia (lack of oxygen) and drying of the gills and skin.\n- Sudden change in pressure during rapid ascent from the seabed, which can cause barotrauma.

Commonly observed signs

These signs are neither exhaustive nor specific. Only a veterinarian can establish a diagnosis.

References

WOAH — Organisation mondiale de la santé animale (ex-OIE)

FAO — Organisation des Nations unies pour l'alimentation et l'agriculture

Content reviewed by the TunisieVet editorial team · Updated 18 August 2026