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

Abstract

Juvenile (83-group) Atlantic mackerel were captured between 1977 and 1980, and in 1988, in the Gulf sf St. Lawrence. Daily rings were identified and validated on their sagittae over the size range 93-1 70 mm; the age of larval and juvenile mackerel was estimated over the size range 7-1 92 mm (fork length). A one-cycle Gompertz curve was fitted to length-at-age data and the parameters were: L, = 5 80.8 mm, K = 8.043, 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 rateof fish from both regions was respectively 1.38 and 1 -02 mm/d in theage interval 10-20 d; 2.38 and 2.07 mm/ d in the age interval 20-383 d; and 2.79 and 2.69 mm/d in the age interval 3 0 4 0 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. Des maquereaux bleus juveniles (groupe 0) ont et6 captures entre 1977 et 1980 et en 1988 dans le golfe du Saint-Laurent. Bes anneaux quotidiens ont 4t4 rep5res et valid& sur les sagittae de ces poissons (93-1 783 mm); ['Age de larves et de juveniles a 4t6 6valu6 sur des sp6cimens dans l'intervalle de taille 7-1 92 mm. Une courbe de Gompertz 2i un cycle a ete adaptee pour les donnees sur la longueur en fonction de l%ge; [es param6tres etaient 22 12Can.

Models describing mackerel (Scomber scombrus) early life growth in the North and Northwest of the Iberian Peninsula in 2000

“…This discrepancy for fish older than 150 days may be interpreted as the result of a possible underestimate of the age of the larger fish. The short axis of the otolith was used to estimate juvenile age and the counts of growth rings on the short axis of the otolith may underestimate the age of the fish (D'Amours et al, 1990). This has also been described by Wild and Foreman (1980), who demonstrate that for yellowfin, the rate at which increments are deposited at the ventral edge is approximately 13 percent lower than the deposition rate on either the postrostrum or rostrum.…”

“…Distinct growth increments were visible on the sagittae of northeast Atlantic mackerel larvae-postlarvae and juveniles-pre-recruits in the Southern Area, which were assumed to have been deposited daily (Migoya, 1989;D'Amours et al, 1990). It was also assumed that increment formation started at hatching, following reports by Migoya (1989) for northwest Atlantic mackerel.…”

“…Previous studies on growth of mackerel larvae and juveniles showed growth curves fitted to the length at age data based on the count of daily increments on otoliths in the Gulf of St. Lawrence (e.g. Kendall and Gordon, 1981;D'Amours et al, 1990;Simard et al, 1992) and in a reduced area in the inner part of the Bay of Biscay (Cotano and Alvarez, 2003).…”

“…The last ring is considered incomplete since it does not represent a full day. The deposition of daily growth rings in mackerel larvae, post-larvae and juveniles has been validated by Migoya (1989) andD'Amours et al (1990) and the direct transformation of number of rings to age in days is justified, although it must be noted that these validations were made for mackerel from a different area, in the northwest Atlantic. Migoya (1989) incubated mackerel eggs in the laboratory at three temperatures and followed the growth of larvae to 13 and 21 days after hatching.…”

“…There is only one reference to somatic growth during the first year of life of the northeast Atlantic mackerel that includes juvenile growth characteristics (Cotano and Alvarez, 2003), although the area sampled was restricted to a small area in the inner Bay of Biscay. Most growth observations on Atlantic mackerel during the first year are from the western Atlantic, along the east coast of North America (Ware and Lambert, 1985;D'Amours et al, 1990;Simard et al, 1992) The discovery of daily increments in fish otoliths (Pannella, 1971 and1974) has made the interpretation of otolith microstructure one of the best tools for estimating age and growth of fish larvae and juveniles (Campana and Neilson, 1985;Jones, 1986;Stevenson and Campana, 1992). Estimating age by counting otolith growth increments provides a direct measurement of length at age for the calculation of growth curves and may also reveal information on individual age and growth rates.…”