The common haddock Melanogrammus aeglefinus is a member of the cod-like fish family. Members have an elongate, tapering body and usually long dorsal and anal fins. Haddock have three dorsal fins and two anal fins. They are easily recognised by the first dorsal fin which is considerably higher than the others, more triangular in outline and has a slightly concave trailing margin. The lateral line is dark in colouration. The haddock has a short and rounded nose, big eyes and a small mouth. It is grey in colouration with dusky brown blotches.Melanogrammus aeglefinus is a valuable species that is exploited commercially in mixed trawl and seine fisheries, along with cod (Gadus morhua) and whiting (Merlangius merlangus), and is a bycatch in Norway lobster (Nephrops norvegicus) fisheries (Hedger et al., 2004). Spawning takes place from March to May, at depths of 100-150 m (Alekseeva & Tormosova, 1979). The easiest ways to tell a haddock from a cod (Gadus morhua) are by the dark colouring of the lateral line and the presence of a dusky blotch just below either of the first dorsal fins.