Stock Identification: Materials and Methods

Abstract

Various population parameters and physiological, behavioral, morphometric, meristic, calcareous, biochemical, and cytogenetic characters have been used to identify fish stocks. We define a stock as an intraspecific group of randomly mating individuals with temporal or spatial integrity. Each character set and the associated methodology relates to specific aspects of the stock definition. Population parameters are useful primarily for the recognition of putative stocks at the practical fisheries management level. Physiological and, to some degree, behavioral characters are used primarily to study differences in the adaptation of stocks to different environments. Behavioral characters are also important for the recognition of stocks and the study of their spatial and temporal discreteness. Morphological characters, including morphometric measurements, meristic counts, and the shape, size, and type of zonation in calcareous structures provide data that are useful for the precise description of and differentiation among stocks. Although the genetic control of this type of variation is poorly understood, multivariate methods coupled with shape analyses provide techniques that describe intraspecific subdivisions that have been found to correspond to genetic stock structure as determined by other methods. Intraspecific chromosomal variation has, on occasion, been employed for stock identification. This variation has had only limited application to the study of stocks because of complications arising from intraindividual variation and artifactual variation introduced by the methodology. Electrophoresis provides an important method for measuring the genetic discreteness of stocks and for the study of genetic relationships among stocks. Electrophoretic data have recently attained a primary position among the methods used for stock identification.Key words: stock identification, genotype, phenotype, population parameters, marking, physiological, behavioral, morphometric, meristic, calcareous, cytogenetic, and biochemical characters