FAH/REU: The Influence of Environmental and Nutritional Event on Recruitment Variability

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Fluctuations in fish recruitment can be precipitated by relatively small variations in mortality rates, growth rates or stage durations in the early life stages of fish. The analyses of growth rate variability which may be more reliable than survey estimation of mortality rates, can provide important insights into the problem of fluctuating recruitment levels. To understand recruitment, it is essential to identify which variables (growth rates, temperature, nutrition) significantly affect larval survival, and subsequent recruitment into the adult population. The use of microstructural otolith analyses, as well as stable isotopic composition of both otoliths and body tissues, will be used as indicators of past environmental temperatures and food conditions. And, through the execution of controlled laboratory experiments, variables which may alter the microstructure of otoliths and the chemical composition of otoliths and of body tissues will be investigated. In addition, the rearing of larvae will provide a unique opportunity for the study of growth, feeding, physiology, and settlement during this important, but elusive phase. The refinement and application of emerging methodologies of otolith analyses will not only further develop and advance the technology, but will also provide answers to applicable fisheries problems.