The ability to manage a fish stock relies on an understanding of life history characteristics and basic biology of the species. Numerous age-growth studies are facilitated by the relative ease of ageing fishes through hard-part analyses. Determining reproductive parameters for fish populations is equally important for stock assessments and management, and histological examination of gonads provides the most accurate determination of fecundity and spawning periods. Coastal pelagic fishes are often targeted commercially and recreationally due to their easy access by private vessels. However, there are few studies researching the biology and reproduction of recreational fishes in the waters of Southeastern Florida that would lead to a better understanding for management practices. The objective of this study was to provide baseline reproductive data for two fishes particularly important to Florida fisheries: the coastal pelagic scombrids Blackfin Tuna Thunnus atlanticus and Little Tunny Euthynnus alletteratus. Archived gonad samples from 2010-2014 for these two species were evaluated, and GSI values and histological examination indicated one spawning season for both species. Little Tunny spawn April through August, and Blackfin Tuna spawn May through June. Additionally both species have asynchronous oocyte development, and are batch spawners. Postovulatory follicles were used to estimate spawning frequency; for Blackfin Tuna, mean spawning occurs once every 1.49 days, and for Little Tunny, mean spawning occurs once every 1.47 days. Comparison of otolith age data to these results indicates that Little Tunny mature at a smaller size and younger age than Blackfin Tuna. Size at 50% maturity for male Blackfin Tuna was 435.2 mm TL, for female Blackfin Tuna was 392.3 mm TL, and for male Little Tunny was 347.77 mm TL. Age at 50% majority for male Blackfin Tuna was 0.66 years, and for male Little Tunny was 0.50 years. In addition to providing important baseline data for fisheries management, this study collaborated with previous research to improve accuracy of reproductive age assessments. Finally, reproductive parameter studies of fishes in Florida and the Greater Caribbean area commercial and recreational fisheries provide information important for future ecosystem based management.

Understanding the life history of a species is essential for fully understanding its role within an ecosystem. However, many of the fish species of high ecological value have not been studied due to their less prominent roles in local recreational and commercial fisheries in comparison to other targeted species. This study describes the age and growth patterns of three small tuna species inhabiting South Florida waters: blackfin tuna Thunnus atlanticus, little tunny Euthynnus alletteratus, and skipjack tuna Katsuwonus pelamis. Tuna specimens were collected via donations obtained from various fishing tournaments and charter captains in the areas of the Florida Straits as well as hook-and-line by the Nova Southeastern University Oceanographic Center. Age was described via sagittal otolith deposition patterns. They were removed, dried, sectioned, and rings were counted as well as measured. Validation of the timing of ring deposits was done by marginal increment analysis. Growth parameters were determined by comparison of fish fork length to count measurements. This comparison via the Von Bertalanffy growth equation produced a growth rate for each species: blackfin, L∞ = 95.34 cm, K = 0.28, and t0 = -1.53; little tunny, L∞ = 77.93 cm, K = 0.69, and t0 = -0.69; and skipjack, L∞ = 112.76 cm, K = 0.24, and t0 = -1.70. The curves indicate an average size of an individual of a given species at a certain age. They also give an estimation of a maximum length (L∞) of each species, in addition to specific growth rate, which is indicated by the slope. Parameters of each resulting Von Bertalanffy equation were compared among species. Results were also 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).