Spatial scaling from latitudinal gradients: Size-specific fecundity in the American lobster Homarus americanus

Abstract

Estimates of key population parameters are required to evaluate conservation or management measures, but are often available at only a few locations within the range of a species. We assembled all available estimates of a single parameter (fecundity as a function of size) in the lobster Homarus americanus to develop a large-scale model applicable throughout the species' range. In this species, a 2-parameter power function, F = aL b, is used to describe the relationship of fecundity F to carapace length L. There was a well-defined latitudinal gradient in the allometric (power law) exponent b, with the smaller values at the northern end of the species' range. The allometric exponent b decreased at a rate of 8.6% per degree of latitude, from southern New England to the northern end of the range (Newfoundland). The scaling factor a increased at a rate of 491 eggs per degree of latitude, as estimated at a carapace length of 85 mm. Fecundity can be estimated from this large-scale model at any location throughout much of the species' range. Data archiving allows re-estimation of parameters when better methods become available, and also allows large-scale models of population parameters to be developed. © Inter-Research 2011.