Midshipman: Photo by roncasual on Flickr.
The midshipman (Porichthys notatus) is a small fish with a large sound. Typically around 6” they inhabit mud flats and inner-tidal zones. Like freshwater carp they can breathe both in and out of water. They are “oviparous” meaning that they deposit eggs, in nests which the males tend.
These animals reached stardom in the US about 30 years ago when the extremely loud humming sound was disrupting the lives of houseboat residents in upscale Sausalito harbor, California. The alien sound was attributed to the military, to some sinister industrial project, and even to extra-terrestrials.
The sample here is produced by two males presumably ‘courting’ a female by way of swim-bladder oscillation. The phasing of their chorus (small time domain shifts over a frequency-synchronized signal) could carry some imbedded information about breeding fitness, or it could be a way of ambiguating the actual source of the signal to predators, or…?
CD Supplement to: “Sounds of the Western North Atlantic Fishes” by Fish & Mowbray, 1970. CD ©University of Rhode Island, 2001.