Did you know that nearly every reef fish can contain toxins produced by dinoflagellates that cause food poisoning called Ciguatera? The toxins cannot be identified by odor, taste or appearance, are transferable sexually, by breast milk and across the placenta and cannot be eliminated by cooking, freezing, salting, drying, smoking, marinating or waiting. The higher up in the food chain, the more toxin the fish contains (by accumulation and biotransformation), which explains that a pigeye shark caused an outbreak of Ciguatera in Madagascar with 500 victims and a death toll of 20 percent in November 1993. Normally this disease causes only neurological or gastrointestinal problems, sometimes recurring or persisting for months or even years (with a death toll up to 2 percent), but shark as a large predator is obviously deadlier. Exported reef fish (supposedly also farm-raised salmon from Chile), unusual fish migration as well as tourism accounts for cases outside the tropics or subtropics, often resulting in insufficient treatment due to unknown and therefore misjudged symptoms (sometimes misdiagnosed as multiple sclerosis). Annually 20 000 to 50 000 people worldwide are suffering from this disease (which is surely an underestimate because of missed diagnoses and underreporting).

The pigeye shark is a species of requiem shark that lives in the tropical and subtropical marine waters of Eurasia, Africa and Oceania and is up to 8.2 ft -2.5 m- long.

Carcharhinus amboinensis ranong.jpg
By Tassapon KRAJANGDARA on www.fishbase.us, CC BY 3.0

The pigeye shark is viviparous, and after the developing embryo depletes its supply of yolk it is sustained to term by its mother through a placental connection formed from the empty yolk sac. After a gestation period of 9 to 12 months the female gives birth to 3 to 13 pups, using sheltered habitats as nurseries. The pigeye shark is a top predator, and it’s size and teeth make it potentially dangerous, though it has not been known to attack humans – if you don’t eat it.

Sources: herehere and here

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