This behavior is called "shoaling", and the waves are said to shoal. Bigfin reef squids also exhibit both schooling and shoaling behaviours. Thresher sharks use their long tails to stun shoaling fishes. Plunge-diving seabirds associate with dolphins and tuna, which push shoaling fish towards the surface. Tank currents can help encourage shoaling behavior. Thresher sharks use their long tails to stun the shoaling fish. Further, by using the WKBJ approximation, wave shoaling and refraction can be predicted. Most, however, are small shoaling fish. They have evolved to find protection by schooling, sometimes with other species like shoaling rabbitfish. It is noted for being a gregarious species, shoaling in large numbers. Size is a sorting mechanism for conspecific as opposed to heterospecific shoaling. One common example is the shoaling of fish. It is also the basis of coastal engineering models for the computation of wave shoaling. Such behaviour has also been demonstrated in the shoaling behaviour of threespine sticklebacks. The NTSB dissenting opinion held that "Edmund Fitzgerald" sank suddenly and unexpectedly from shoaling.