Chapter 7 - Morphometric Landmarks

Abstract

Patterns of morphometric variation in fishes indicate differences in growth and maturation rates because body form is a product of ontogeny. Morphometric landmark methods comprise one of the two major categories of orphometric analysis, the other being outline methods. In the context of interdisciplinary stock identification, or the use of information from various approaches, morphometric analysis provides information on phenotypic stocks, groups of individuals with similar growth, mortality, and reproductive rates. The phenotypic stock definition is less conservative than the genetic stock definition because it allows for some mixing among stocks, but partial isolation is enough that geographic differences persist. Despite dependence on the environment, ontogenetic rates influence many population attributes (e.g., reproduction, fecundity, longevity, size structure) that are intimately related to population dynamics (intrinsic rate of increase, carrying capacity, productivity, resilience, and so on) and determine how each stock responds to exploitation. Therefore, for the purpose of fishery stock assessment, groups with different growth or reproductive dynamics should be modeled and managed separately, regardless of genetic homogeneity. This chapter reviews common protocols for sampling, analyzing, and interpreting variation associated with morphometric landmarks for stock identification applications.