Age and Growth of Coastal Pelagic Tunas

Grant Winners

Deans

Abstract

Understanding the life history of a species is essential for comprehending its role within an ecosystem. However, many of the fish species of high ecological value have not been studied due to their lesser roles in recreational fisheries. We propose describing the age and growth patterns of the small tuna species inhabiting South Florida waters. Tuna specimens will be collected via donations obtained from various fishing tournaments and charter captains in the areas of the Florida Straits as well as gillnetting and hook-and-line by Nova Southeastern University Oceanographic Center students. Age will be described via sagittal otoliths. They will be removed, dried, sectioned, and rings will be counted as well as measured. Validation of the timing of ring deposits will be done by marginal increment analysis. The completion of the outermost ring will be estimated by comparing the ratio of previous ring sizes. The resulting times of ring formation will be compared between species. Growth parameters will be determined by comparison of fish standard length to otolith length and count measurements. This comparison via the Von Bertalanffy growth equation will produce a growth rate trend for each species, as well as between sexes. The curve will indicate an average size of an individual of a given species at a certain age. It will also give an estimation of a maximum length of each species in addition to growth rate, which is indicated by the slope. Parameters of each equation will be compared among species and between sexes. Results will be compared with growth rates currently used in stock assessments by fisheries management organizations, such as the International Commission for the Conservation of Atlantic Tunas (ICCAT).