Theses and Dissertations


Name: Bourque, Bradford Daniel

Degree: MS

Chair: Ronald P. Phelps


University: Auburn University

Location: Auburn, Alabama

Date: 2001

Pages: 101

Keywords: Red snapper, reproduction, hormone injection, induced spawning, egg hatch


A study was conducted to evaluate the egg quality produced by several protocols to induce spawning in red snapper. Seven trials were attempted where brood red snapper were captured from the wild, induced to ovulate by HCG injection, eggs and sperm manually stripped, and the eggs artificially fertilized. These eggs were evaluated by the following egg quality parameters: buoyancy, fertilization, egg size, oil globule size and number, and appearance (shape and clarity). The relationship of these egg quality parameters and brood characteristics (female size, fecundity, time of year, response time h to ovulation) to 36 hours post hatch larval survival was considered. No clear relationships were found but rather a combination of factors may be more predictive of survival, most notably spawn date, fecundity and response time to ovulation. Several protocols to induce a natural spawn were also attempted (1) LHRHa injection (20 ug/kg for females, 10 ug/kg for males) (2) LHRHa EVAc implant, (lOOug/kg for females, 50 ug/kg for males) (3) LHRHa injection (20 ug/kg for females, 10 ug/kg for males) plus 1 mg/kg pimozide injection, (4) 150 ug/kg LHRHa EVAc implant for females, 20 ug LHRHa injection plus 1 mg/kg trenbolone acetate injection (5) LHRHa injection (100 ug/kg for females, 50 ug/kg for males) (6) LHRHa cholesterol implant (150 ug/kg for females, 125 ug/kg for males) plus prostaglandin/progesterone application. Red snapper were captured from the wild, injected or implanted with the hormone treatment, stocked into photothermal control tanks, and allowed to spawn naturally. Eggs were collected daily after release. Protocols were compared in terms of the quality of the eggs produced and the numbers of eggs released per kg female. All treatments but the lowest LHRHa dose induced one or more egg releases. The highest LHRHa injection dose given to males (50 ug/kg) was the only treatment to produce fertilized eggs. The cholesterol implants together with prostaglandin/progesterone application produced the largest amount of egg release (140,000 eggs/kg).

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