Regional differences in allometric growth in Atlantic Canadian lobster (Homarus americanus)

Abstract

Allometric growth in three groups of American lobsters (Homarus americanus) found along the Northumberland and Atlantic coasts of Nova Scotia was compared. Three morphometric parameters were measured: (1) abdomen area, (2) carapace length, and (3) chelae length. Abdomen area and chelae length measurements were related to both carapace length and nominal length, which is (body mass)1/3, while carapace length was related to nominal length. The scaling factors of abdomen area with carapace length for female lobsters were regionally different and were significantly greater than the isometric value of 2. Comparisons were made to published data for the scaling factors of abdomen area for the California spiny lobster (Panulirus interruptus) and differences were found. The data for Homarus were compared to previous measures of the scaling of fecundity for lobsters collected from similar regions of the province. The comparisons suggest that fecundity estimates used in current management strategies should be measured on a regional basis. Carapace length does not exhibit isometric growth when related to nominal length, and significant differences in relative growth exist between sexes. Chelae morphometrics were also regionally different for male lobsters and did not exhibit isometric growth.