Chapter 1: History and Importance of Age and Growth Information
Janice A. Kerns and Linda A. Lombardi-Carlson
Knowledge of fish age and rate of growth is essential to understanding the inner workings of fish population dynamics and fisheries management. Generally, growth can be defined as the change in length or weight over the life of an individual. Age and growth can be measured across multiple temporal intervals (e.g., days, months, years) and can be used to characterize important life history characteristics. Age of an individual fish is required to estimate growth rate, age at recruitment, maturity schedules, and age-specific fecundity. Growth affects a fish’s vulnerability to predation and fishing and is a metric of prey resource availability for individual fish. Both parameters are influenced by environmental conditions and can indicate body condition of an individual fish or the stability of a population.
Growth, mortality, and recruitment are the primary biological rates of interest in fisheries management and research (Hilborn and Walters 1992; Maceina et al. 2007). With information on population rate functions, managers can monitor populations and develop science-based regulations to meet specific management, conservation, or restoration goals. For example, information on fish growth has been used to assess projected effects of climate change on aquatic systems (King et al. 1999), habitat quality on survival (Quinn and Peterson 1996; Suttle et al. 2004), prey availability (Rennie et al. 2009), predation risk (Werner et al. 1983), density-dependent interactions (Lorenzen and Enberg 2002), and the efficacy of harvest regulations (Beamish et al. 2006; Rypel 2015).