Partial Length as a Replacement for Total Length in Measuring Grenadiers

Abstract

The problem of tail breakage and regeneration in grenadiers instigated the initiation of studies to find a suitable partial length measurement as a replacement for the traditional total length measurement. Studies undertaken in 1978 and 1979 on roundnose grenadier, Coryphaenoides rupestris, indicated that the partial length mesurements, pre-anus length and anal-fin length, were highly correlated with total length. The anal-fin length was considered to be more practical than pre-anus length, as the latter is sometimes affected by distortion of the anus due to air-bladder expansion and extrusion of intestines when the fish are brought to the surface from deep water. Consequently, the Scientific Council of NAFO at its meeting in June 1980 adopted anal-fin length (tip of snout to base of first anal fin ray) as the standard for measuring roundnose and roughhead grenadiers.