|Riley, Kenneth - HBOI|
Submitted to: Book of Abstracts Aquaculture America
Publication Type: Abstract Only
Publication Acceptance Date: September 15, 2006
Publication Date: February 1, 2007
Citation: Riley, K.L., Weirich, C.R. 2007. Use of imaging analysis for modeling growth and development of larval Florida pompano [abstract]. Book of Abstracts Aquaculture America. p. 780. Technical Abstract: The Florida pompano Trachinotus carolinus is a prime candidate for aquaculture; however, the successful production of juveniles to stock ongrowing operations remains a major impediment to commercial culture of this species. As with many marine fish species, rearing larvae through metamorphosis can be challenging and difficult. The knowledge of the early life history of fish is essential not only for the improvement of hatchery techniques, but also for evaluating new species for culture. The goal of this study was to use digital photography and image analysis to investigate the early life history of Florida pompano. The specific objectives were to: (1) develop photographic techniques for evaluating larval ontogeny; (2) compare the morphological variation among larvae from three different spawns; (3) document time of occurrence for critical periods including first feeding, yolk and oil globule exhaustion, transition in diet, and onset of metamorphosis, and (4) develop a model feeding regime for pompano larvae. In three independent larval rearing trials, approximately 50,000 larvae were stocked into a 0.8-m3 tank. To maintain green water culture conditions, tanks were inoculated at 2 days after hatching (DAH) with microalgae, Nannochloropsis oculata. Larvae were fed enriched rotifers from 2 days after hatching through 15 DAH and Artemia nauplii from 12 DAH through 20 DAH. Samples of 10 larvae were collected daily from hatching (0 DAH) through completion of metamorphosis (ie. 20 DAH). Larvae were euthanized, digitally photographed, and measured using image analysis software. Newly hatched larvae were transparent and small (SL = 2.5 ± 0.09) with a large, elongate yolk sac and single oil globule. The lower and upper jaws as well as the digestive tract were not fully developed at hatch. Rotifers were observed in the stomach of larvae at 3 DAH, and Artemia were observed in the stomach of larvae with rotifers at 14 DAH. Growth rates (means ± SE) calculated from TL measurements were 0.22 ± 0.04, 0.23 ± 0.12, and 0.35 ± 0.09 mm/d for each of the larval rearing trials. The mouth gape of larvae was 266 µm at first feeding and increased with a growth rate of 0.13 ± 0.04 mm/d. Predicted values for optimal prey sizes ranged from 80 to 130 µm at 3 DAH, 160 to 267 µm at 5 DAH, and 454 to 757 µm at 10 DAH. As a result of this study a refined feeding regime was developed to provide stage- and size-specific guidelines for feeding pompano larvae reared under hatchery conditions.