Size–Maturity Relationships and Related Observations in Newfoundland Populations of the Lobster (Homarus americanus)

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Abstract
Female maturity ogives for 5 Newfoundland populations of the lobster (H. americanus) gave 50% maturities ranging from 71-76 mm carapace length. Sizes at which distinct inflections (indicating onset of maturity) and asymptotes (indicating 100% mature) are present in the abdomen width/carapace length ratio vs. carapace length relationships coincide with the smallest ovigerous and largest immature specimens, respectively, observed in those particular samples. Inflection in the crusher claw weight/whole weight ratio vs. carapace length relationships (used to indicate onset of maturity in males) occurred at larger sizes than inflections in the abdomen width/carapace length ratios of females. The percentage of nonovigerous females that spawn in a given year generally increases with increasing size. The highest percentage of nonovigerous females tagged with sphyrion tags prior to the spawning season that were ovigerous when recaptured 10-12 mo. later was 83.8%. The percentage of ovigerous females with new shells (i.e., molted and spawned in same year) varied between areas and years and ranged from 0-38.5% of the total number of ovigerous females in fall samples. The percentage of ovigerous females in samples also varied between areas and years and ranged from 2.6-30.4% of the total number of females greater than the size at 50% maturity. A greater percentage of females was ovigerous at sizes between the size at 50% maturity and 80 mm (largest subcommercial size) than at commercial sizes. In a sample of nonovigerous females, the size range at which 50% were fertilized (76-80 mm) coincided closely with the size at 50% maturity (75 mm) for the area. At subcommercial sizes (< 81 mm) the sexes were approximately equally represented in fall trap-caught samples but females heavily outnumbered males in diver-caught samples taken over the same period. At commercial sizes males heavily outnumbered females in the trap-caught samples while in diver-caught samples the sexes were equally represented.

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