Growth of Juvenile (0-Group) Atlantic Mackerel (Scombrus) in the Gulf of St. Lawrence

Abstract

Juvenile (0-group) Atlantic mackerel were captured between 1977 and 1980, and in 1988, in the Gulf of St. Lawrence. Daily rings were identified and validated on their sagittae over the size range 93–170 mm; the age of larval and juvenile mackerel was estimated over the size range 7–192 mm (fork length). A one-cycle Gompertz curve was fitted to length-at-age data and the parameters were: L∞ = 180.8 mm, K = 0.043, and to = 37.7 d. The maximum calculated growth rate was 2.86 mm/d. The growth rate of 0-yr mackerel from the Gulf of St. Lawrence could be faster from that reported for 0-yr mackerel from the Middle Atlantic Bight: the mean growth rate offish from both regions was respectively 1.38 and 1.02 mm/d in the age interval 10–20 d; 2.30 and 2.07 mm/d in the age interval 20–30 d; and 2.79 and 2.69 mm/d in the age interval 30–40 d. This difference in somatic growth rate could provide the basis for determining the origin of adult fish if it resulted in permanent and discernible records on the otoliths, and if otolith growth is coupled with somatic growth.