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Five test diets – 20, 10 rotifers/mL/d, 5 rotifers/mL/d + 3 nauplii/mL/d, 5 and 8 nauplii/mL/d – were used to examine the effect of Acartia tonsa nauplii and a small strain of rotifers on survival, myotome height, notochord length, and condition (myotome height/notochord length) of spotted seatrout, Cynoscion nebulosus, larvae through 6‐d posthatch (PH). Diet did not affect survival. Larvae fed 5 and 8 nauplii/mL or 5 rotifers + 3 nauplii were longer, taller, and in better condition than larvae fed either 10 or 20 rotifers/mL. The condition of larvae fed diets with nauplii declined after Day 5 which suggests a shortage of prey in those diets after Day 4 or 5. Although copepod nauplii offer substantial short‐term benefits in the culture of spotted seatrout, further study is required to determine the number of nauplii and/or rotifers necessary in the diet beyond Day 4 and to assess the long‐term impact of the different diets.

Gametogenesis was monitored histologically in wild‐caught red snapper (Lutjanus campechanus, Poey) maintained in captivity under simulated natural photothermal conditions. Gonads were collected every 2–3 weeks (average n = 14) for histology during the pre‐spawning season (February to May, temperature increasing from 16°C to 24°C). Primary vitellogenic oocytes were first observed in one female when temperature reached 20°C. Subsequent samples revealed females in pre‐vitellogenesis or at early stages of vitellogenesis, although one female had tertiary vitellogenic (Vtg3) oocytes. The first histological signs of spermatogenesis were observed when temperature reached 17°C. Spermatozoa were observed in testicular lobules of all males sampled on 14 May (24°C) but little or no sperm was released during manual stripping. Ten males and 10 females were left in tanks and monitored for spawning. No egg release was observed during the monitoring period that encompassed the natural spawning season of wild red snapper. Ovarian biopsies taken during the late spawning season (16 July) revealed that four of eight sampled females had Vtg3 oocytes. Males were manually stripped but released no sperm. These results indicate that captive red snapper can complete gametogenesis in photothermal controlled systems. Additional research is needed to develop procedures that will achieve reliable maturation and spawning.

The Tripletail, Lobotes surinamensis, is a warm-water pelagic fish that is increasingly targeted by U.S. anglers. The superior quality of Tripletail flesh coupled with the lack of domestic commercial fisheries stimulated interests to develop aquaculture of this species. In this work, photothermal conditioning of captive-held broodstocks promoted maturation in females, but spontaneous spawning was not observed. GnRHa slow-release implants induced ovulation in late vitellogenic females but fertility remained below 10% when GnRHa was administered alone. However, spawns with high fertility (up to 85%) were obtained when a dopamine antagonist was administered in conjunction with GnRHa implants indicating dopamine inhibition impaired final gamete maturation, in particular sperm production in males, in aquaculture conditions. Tripletail larvae successfully initiated exogenous feeding on enriched rotifers followed by Artemia nauplii and were weaned to prepared feeds at 25 days post hatch, yet with low survival through the late phases of larval culture. Pilot grow-out trials at low density in recirculating systems revealed impressive growth rates averaging over 170 g/month through a market size M201-13-01; Perciformes Group LLC

Two experiments were performed to investigate increasing the number of copepod nauplii obtained from a brown-water zooplankton culture for feeding to larval red snapper Lutjanus campechanus. Brown-water zooplankton cultures rely on the regular exchange of (brown) estuarine water to nourish and harvest the copepods. The majority of copepods in both experiments were Acartia tonsa. The goal of the first experiment was to determine whether adding rice bran to a brown-water zooplankton culture would increase copepod density. Brown-water zooplankton cultures supplemented with rice bran had significantly higher naupliar densities than either brownwater zooplankton cultures without rice bran or zooplankton cultures supplemented with rice bran but without brown-water exchanges. Both the rice-bran-supplemented brown-water zooplankton culture and the rice bran zooplankton culture had higher copepodid densities than the brown-water zooplankton culture, but they were not different from each other. The goal of the second experiment was to determine the harvest rate (25, 50, and 75% of the water volume every other day) that would produce the most copepods. Copepod densities increased with a decrease in harvest rate; however, naupliar yields increased with increasing harvest rate. Copepod populations subjected to the various harvest rates appeared to undergo similar dynamics and were thus equally sustainable. There were significantly more nauplii harvested with the 75% harvest rate than with the other rates, but there was no difference in the number of harvested copepodids resulting from the different harvest rates. Naupliar yields of brown-water zooplankton cultures may be increased by rice bran supplementation and harvesting 75% of the culture volume every other day.

The Atlantic Croaker Micropogonias undulatus (Sciaenidae) is a candidate species for marine baitfish aquaculture in the southeastern United States because of its high value and common use as live bait by recreational fishers. However, an efficient larviculture procedure has not been reported to date; development of such a procedure was the impetus for this study. Embryos were obtained from captive broodstock that were induced to spawn volitionally by using a single injection of a luteinizing hormone releasing hormone agonist. Larvae were cultured at low density (initial density = 6.4 larvae/L) via intensive culture methods, including the use of recirculating filtration systems and of rotifers, brine shrimp Artemia spp., and micropellets as larval foods. The trial was performed in six 1,100‐L tanks at a salinity of 14–29‰, with average rearing temperatures of 23.6°C and 24.6°C. At the completion of the study (39 d posthatch), mean SLs were 24.7 mm (SE = 0.738) for larvae cultured at 24.6°C and 23.0 mm (SE = 0.624) for larvae cultured at 23.6°C. Mean survival at 39 d posthatch was 25.9% and did not differ significantly between temperature groups. This work demonstrated a successful methodology for intensive larviculture of Atlantic Croakers and can serve as a platform for the experimentation that will be necessary to develop economically viable procedures for intensive production of this species.

The Tripletail, Lobotes surinamensis, is a pelagic fish found in tropical and sub-tropical waters of all oceans. Tripletails are often associated with floating debris and make frequent incursions in bays and estuaries where they are targeted by recreational fishermen. In Mississippi waters the species is typically present during the late spring and summer season that also correspond to the period of sexual maturation and spawning (Brown-Peterson and Franks 2001). Tripletail is appreciated as a gamefish but is also prized for its flesh of superior quality. The fast growth rate of juveniles in captivity documented by Franks et al. (2001) and the excellent quality of Tripletail flesh both contribute to the potential of this species for marine aquaculture. In addition, the production of cultured juveniles would be precious to develop a better understanding of the biology, early life history and habitat use of Tripletail larvae and juveniles, a topic largely undocumented to date, through experimental releases and controlled studies. The culture of tripletail thus supports the Tidelands Trust Fund Program through improved conservation of natural resources, potential enhancement of fisheries productivity and potential development of a new economic activity on the Gulf coast producing tripletail via aquaculture. The Objective of this project was to initiate development of methods and techniques needed to spawn captive held tripletail broodfish and raise their offspring to evaluate their growth and development in captivity. In this report we will present the results of studies aiming to develop methods and protocols for captive spawning of tripletail and the first data obtained on the early development of tripletail larvae. A major issue that was encountered with tripletail broodstock development during the project lied in the difficulties associated with identifying the sex of adults caught in the wild and candidates for being incorporated in mating sets for spawning. This issue was addressed during the course of the project by examining the potential of a non-lethal method of hormonal sexing. The results of these preliminary investigations are presented in the third part of this report. All protocols used in the project were determined with the guidance of the Institutional Animal Care and Use Committee (IACUC) of the University of Southern Mississippi (USM IACUC protocol number 10100108).