Pollack
Otolith description
The shape of the otoliths is ovally pointed. When looked upon from the side the otolith is strongly curved. The sulcus is well developed and wide. The sulcus is closed, but runs over almost the whole length of the otolith. The ostium and cauda are well developed and separated by a narrowing of the sulcus. The cauda is longer than the ostium. The surface of the inside is smooth, while the outside and margins are lobate. The rostrum is not well developed and round lobate. The antirostrum is indistinct. The posterior margin is pointed. The inside of the otolith is convex and the outside strongly concave from the anterior to the posterior but also from the ventral to the dorsal side. The otolith is thick as in most gadidae. Otoliths of gadidae, except rockling otoliths, are all very large and mostly robust otoliths.
Pollack otoliths are hard to distinguish from other gadidae. Saithe Pollachius virens are almost impossible to distinguish from pollack. The only difference is that saithe otoliths are less lobate at the outside and the margins. Cod Gadus morhua and haddock Melanogrammus aeglefinus are less concave. The sulcus of pollack is wider. Whiting Merlangius merlangus and blue whiting Micromesistius poutassou are longer, more pointed and also flatter and thinner than pollack otoliths. Otoliths of Trisopterus spp. are thicker and wider and are more lobate at the outside. Otoliths of tadpole-fish Raniceps raninus have a sulcus in which the ostium and cauda are completely separated. Tadpole-fish otoliths are flat and have one strongly protruding lobe on the outside of the otolith.
In eroded otoliths the sulcus is less clear and the margins are smoothed. The outside remains slightly lobate.
Fish length and distribution
Pollack can grow up to 130 cm. Pollack is a demersal fish (POLLPOLL.TIF) that is found in inshore waters. It forms schools over rocky grounds and wrecks. It spawns from January to April in deeper waters (Wheeler, 1978, Nijssen and De Groot, 1987, Knijn et al., 1993, Muus et al., 1999).
Pollack is found in the Northern Atlantic and North Sea.
Sample origin
Fyke, and some larger specimens from northern North Sea.