Comparing growth and maturity of sympatric Atlantic (Gadus morhua) and Greenland (Gadus ogac) cod in coastal Newfoundland

Abstract

Growth and maturity of two sympatric gadids were examined from 48 Atlantic (Gadus morhua L., 1758) and 42 Greenland (Gadus ogac Richardson, 1836) cod ranging from 17 to 74 cm in length collected from an inshore area of Trinity Bay, Newfoundland, Canada, during 2009 and 2010. Ages estimated from otolith readings ranged from 2 to 7 for both species. Age and size at 50% maturity differed between species, being 2.3 years and 28.2 cm for G. ogac and 4.6 years and 48.8 cm for G. morhua. von Bertalanffy growth models did not differ between species with parameters L∞ = 91 cm, k = 0.16 year−1, t0 = –0.02 years for G. ogac and L∞ = 112 cm, k = 0.13 year−1, t0 = 0.18 years for G. morhua. Length (L) – mass (W) relationships differed; W = 0.000005 kg·cm−b × L3.17 for G. ogac and W = 0.000011 kg·cm−b × L2.91 for G. morhua suggested slightly positive and negative allometric growth, respectively. For G. morhua, growth curves, length–mass relationships, and maturity rates did not differ between fish collected during this and earlier studies. Differences in maturity schedules and growth may decrease resource competition and help facilitate coexistence of these species.