Shrake

Shrake is a magically-created species of saltwater fish, found in the Atlantic Ocean, which is covered in spines and which deliberately seeks out and destroys Muggle fishing nets. The first shrake were supposedly created in the 1800s by a group of wizard fisherfolk who had been insulted by Muggles. The shrake, by damaging the nets used by Muggles to fish in that area of the sea, cause no end of trouble (FB).