Spinal Nerve innervation to the Sonic Muscle in Walleye Pollack, Theragra Chalcogramma (gadidae: Gadiformes)

The Walleye Pollack (Theragra chalcogramma) produces sounds by contractions of a pair of intrinsic sonic muscles located on the swimbladder. The innervation pattern of this muscle was investigated. It is innervated by branches (sonic branches) of the third to eighth spinal nerves. The Walleye Pollack was found to be one of the rare sonic fishes with the sonic muscle innervated only by the spinal nerves.