Poor cod
Otolith description
The shape of the otoliths is ovally pointed. When viewed from the side the otolith is curved. The sulcus is well developed and wide. The sulcus is closed, but runs over almost the whole length of the otolith, pointing down at the posterior. The ostium and cauda are well developed and separated by a narrowing of the sulcus. The cauda is longer and wider than the ostium. The surface of the inside is smooth, while the outside and margins are strongly 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 concave. The otolith is thick at the anterior while thin at the posterior. Otoliths of gadidae, except rockling otoliths, are all very large and mostly robust otoliths.
Otoliths of all Trisopterus species that occur in the North Sea are thicker and shorter, and more lobate at the outside, compared to other gadidae. Poor cod otoliths are hard to distinguish from other Trisopterus species, but have the smallest length to width ratio within this group. Otoliths of norway pout T. esmarkii are smooth on the outside and margins compared to poor cod otoliths. The cauda and ostium are of the same width. Bib T. luscus tends to be less lobate and have smaller lobes on the outside than poor cod. Also the cauda tends to be narrower when compared to poor cod. Trisopterus spp. are the smallest of the gadidae and otoliths are <12 mm in length. Otoliths of bib can be larger than 10 mm, while otoliths of poor cod and norway pout do not exceed 10 mm.
In eroded otoliths the sulcus is less clear. The outside and margins remain lobate.
On otoliths of juvenile poor cod the sulcus is less distinct. The margins and outside are already slightly lobate.
Otoliths of juvenile fish already have the same features of larger otoliths.
Fish length and distribution
Poor cod can grow up to 26 cm. Poor cod is a demersal schooling fish (TRISMINU.TIF) that is found in coastal waters. It spawns from February to April (Wheeler, 1978, Nijssen and De Groot, 1987, Witte et al., 1991, Knijn et al., 1993, Muus et al., 1999).
Poor cod is found in the NE Atlantic and North Sea.
Sample origin
Mostly Southern North Sea, but also fyke.