Recruitment and Young Fish

Otoliths are of considerable value in studies of recruitment processes, as well as larval and juvenile fishes. Much of this work is associated with the examination of the otolith microstructure (see Microstructure and daily increments) and the determination of growth patterns (see Growth models and backcalculation). Applications specific to young fish include the determination of daily age and hatch date, growth rate and mortality rate. When these age-structured estimates are combined with independent information on population abundance, temperature, currents and spawning patterns, factors influencing recruitment (= yearclass strength) can be evaluated. Particularly important in this regard are relationships between the environment and growth rate, larval drift patterns, hatch date frequencies as compared to spawning production, and the relationship between growth rate and mortality rate. Examples of these and other applications are presented in Campana (1984a), Campana and Hurley (1989), Campana et al. (1989b,c), Suthers et al. (1989), Campana and Jones (1992), Oxenford et al. (1994), and Campana (1996)