Trachinotus Carolinus, Induced Via Administration of Gonadotropin Releasing Hormone Analogue (Gnrha)
Total Page：16
File Type：pdf, Size：1020Kb
Volitional Spawning of Florida Pompano, Trachinotus carolinus, Induced via Administration of Gonadotropin Releasing Hormone Analogue (GnRHa) Charles R. Weirich Kenneth L. Riley ABSTRACT. Renewed interest in the culture of Florida pompano, Trachinotus carolinus,a high-value species first identified as an excel lent candidate for mariculture over three decades ago, has occurred in re cent years. To support the development of pompano mariculture, trials were conducted in 2004 and 2005 to evaluate captive reproduction of pompano via gpnadotropin releasing hormone analogue (GnRHa) in duction. Adult pompano collected seasonally beginning in 2003 from the wild were subjected to quarantine and feed training. Fish were held in recirculating tank systems (sex ratio I: I) under controlled photo thermal conditions and were sampled periodically to assess health and reproductive condition. To initiate spawning, ripe females (mean oocyte diameter> 500 11m) and males were implanted with a 751lg GnRHa pel let. Fish spawned approximately 36 hours post-implantation and eggs were collected and stocked into incubation tanks (24-26°C) with hatch ing OCCUlTing approximately 30-36 hours post-fertilization. In 2004, three spawning trials were conducted resulting in the production of 4.4 million eggs, of which 979,000 (22.0%) were floating (mean fertiliza tion rate 81.8%). In 2005, six trials were conducted resulting in the pro duction of 5.8 million eggs, of which 2.5 million (42.7%) were floating Charles R. Weirich, USDA-ARS Sustainable Marine Aquaculture Systems Pro gram, 5600 US 1 North, Fort Pierce, FL 34946. Kenneth L. Riley, Aquaculture Division, Harbor Branch Oceanographic Institu tion, 5600 US 1 North, Fort Pierce, FL 34946. Journal of Applied Aquaculture, Vol. 19(3) 2007 Available online at http://jaa.hawOfthpress.com © 2007 by The Haworth Press, Inc. All rights reserved. doi: 1O.l300/J028v19n03_03 47 48 JOURNAL OF APPLIED AQUACULTURE (mean fertilization rate, 96.9%). Hatching rate of fertilized eggs in trials conducted ranged from 73.1-95.4%. Results to date indicate that pom pano broodstock can be readily spawned in captivity over extended peri ods oftime through GnRHa implantation. Although moderate variability in egg quality between spawning events has been observed, pompano produce relatively large quantities of eggs necessary for mass produc tion of seed stock. doi:10. 1300/J028v19n03_03 [Article copies availablefora fee from The Haw0I1h Document Delivery Service: I-800-HAWORTH. E-mail ad dress: <[email protected]> Website: <http://www.HaworthPress. com> © 2007 by 171e Haworth Press, Inc. All rights reselved.] KEYWORDS. Trachinotus carolinus, Florida pompano, reproduction, GnRHa INTRODUCTION Florida pompano, Trachinotus carolinus, (family Carangidae) are found primarily inU.S. coastal waters from Floridato North Carolinaand throughout the Gulf of Mexico (Gilbert and Parsons 1986). Atlantic spawning occurs from February to October at 22-26°C, with peaks in April to May and September to .October (Fields 1962), and may occur yearroundin the Gulf(Berry andrverson 1967). Larvae spend a month at sea, while juveniles inhabit the surf zone until temperatures are <20°C, when they migrate offshore (Fields 1962; Iverson and Berry 1969). Fish mature at one to three years ofage andno.rmally attain a maximumweight ranging from 0.7 to 2.3 kg (Gilbert and Parsons 1986). Considered one of the finest and most desirable marine table fish, pompano commands a significantly higher price than many other U.S. marine and freshwater finfish species (Watanabe 1995). In 2003, theav erage wholesale price ofwhole pompano was US$7.42/kg and, depend ing on time ofyear and availability, the price ofpompano fillets canreach $35/kg (NMFS 2004). Recreational and co.rnmercial pompano fisheries exist along the south Atlantic and Gulf coasts ofthe United States, with 83-92% of landings occurring in Florida (Watanabe 1995). Because pompano landings have never been large relative to the total U.S. com mercial fishery, demandhas consistently exceeded supply. From 1994 to 2003, annualcornmerciallandings ofpompano averagedless than 275,000 kg peryear, with a value slightlyless than US$1.8million(NMFS 2004). Due to its high market value, significantinterestin the culture ofpom pano developed in the United States during the 1960s and 1970s and, as a result, efforts were initiated to develop culture methods for this species Charles R. Weirich and Kenneth L. Riley 49 (Watanabe 1995; Craig 2000). In addition, a handful ofcommercialven tures were established during this period. Although it was determined that pompano exhibit several desirable characteristics for mariculture, researchers and commercial culturists alike were largely unsuccessful in rearing pompano to marketable sizes (e.g., >450 g). Further, techniques for mass production of seed stock were not fully developed. Lackoftechniques for sustainedseed stock to supply grow-out opera tions is one ofthe foremost bottlenecks ofmarine finfish aquaculture de velopment (Bromage 1995; Dhert et al. 1998). Seed stock production of several marine finfish has been achieved; however, most activity has oc curred outside the United States(Tucker 1998), With respect to pom pano, preliminary work by Hoff et al. (1972, 1978a,b) indicated that pompano can be conditioned to spawn (by strip and volitional spawning methods) under varying photothermal conditions via administration of human chorionic gonadotropin (HCG). Although eggs were produced, fertilization rates were highly variable and many eggs exhibited abnor mal development. While this initial workledto atleastone reported com mercial scale attemptat mass production ofpompano in the early 1970s (McMaster 1988;Watanabe 1995), additionalresearchefforts to develop and refine reproduction protocols for this species have.been few. It is likely that pompano reproduction could be improved with enhanced broodstock diets coupledwith the use ofotherhormonal induction agents such as gonadotropin releasing hormone analogues (Chang and Jobin 1994; Zohar 1996; Crim and Bettles 1997; Powell et al. 1998; Mylonas and Zohar 2001; Zohar and Mylonas 2001). Toexpandontheresults ofinitial studies, a series ofreproductiontrials were undertaken with the goal of developing consistent and reliable methods for sustainable seed stockproduction ofpompano. Specifically, broodanimals were collectedfrorn the wild, and afterquarantine and feed training, were induced to spawn volitionallY via GnRHa induction to ascertain egg quantity and quality. MATERIALS AND METHODS Broodstock Acquisition, Quarantine, and Feed Training Adult pompano were acquired from local commercial fishermen dur ing fall 2003, winter 2004, and spring 2005. Approximately 40fish were collected each year. Fish were collected in the Indian River Lagoon 10- 50 JOURNAL OFAPPLIED AQUACULTURE cated along the east-central coast of Florida. After capture, fish were transported to USDA-ARS aquaculture facilities at Harbor Branch Oceanographic Institution and placed in 8,000-12,000 L recirculating tanks (19-29°C; salinity, 28-30 gIL; natural photoperiod). Over the courseofatleasttwo months, newly acquiredfish were subjectedto addi tions of copper sulfate (0.25 mglL as Cu2+; Cutrine®-PlusAlgaecide/ Herbicide, Applied Biochemists, Milwaukee, Wisconsin 1) and prazi quantel (2.5 mglL; PondRx.com, Morganton, Georgia) to eradicate pro tozoanand monogenetic trematode parasites, respectively. During the quarantineperiod, fish were feed-trained by gradual transi tion from natural prey items to formulated diets. Specifically, peeled shrimp, cut squid, and sand fleas, Emerita talpoida, were offered for the first two weeks after capture, and a moist diet (Fish Breed-M; 62% pro tein, 16% lipid; Inve Americas, Inc., Salt Lake City, Utah) mixed with peeled shrimp was then fed for oneweek. Fish were subsequently starved for four to five days and the moist dietwas fed alone for one week. There after, the moist diet was fed in combination with a sinking pelleted diet (Lansy Breed; 47% protein, 18% lipid; Inve) for an additional week, and subsequently the pelleted diet was fed alone. During feed training, fish were fed at a rate of1-2% body weight. The total daily ration was divided into two feedings administered at 0900 and 1600 hours. Fish Inventory Upon completion of quarantine and feed training, weight and sex of fish were determined after sedation in a 3,000L rectangular tankthrough the useof75 mglLtricaine methanesulfonate (MS-222; ArgentChemical Laboratories, Redmond, Washington). Additionally, passive integrated transponder (PIT) tags were implanted subcutaneously in the lateral musculature for future identification via a MPRTM PIT tag reader (Bio mark, Inc., Boise, Idaho). Thepresence or absence ofan oviduct through visual inspection ofeach fish was used to determine sex. In 2004, mean weight ofmale and female pompano was 0.7 and 1.3 kg, respectively. In 2005, mean weight of male and female fish was 1.0 and 1.6 kg, respec~ tively. In both years the sex ratio of the total broodstock population fish approximated 1: 1. 1. Use of trade or manufacturer's name does not imply endorsement. Charles R. Weirich and Kenneth L. Riley 51 Oocyte Sampling Immediately before initiation ofindividual spawning trials and peri odically throughout the months fish were spawned in 2004 and 2005, fe males were sedated and ovariantissue was removed via the insertion ofa 10 em section of20-gauge teflon tubing attached to a 3.0 mL syringe. A small