World Aquaculture September 2018

WWW.WA S.ORG • WORLD AQUACULTURE • SEP TEMBER 2018 51 Acute salinity tolerance. This experiment was performed in the same way as the acute temperature tolerance study, except that 50 juvenile pigfish were transferred directly from a salinity of 32 g/L to each of five different salinities (12, 17, 22, 27, or 32 g/L). Mean length and weight at the start of the study were 4.6 ± 0.2 cm and 1.5 ± 0.2 g, respectively. At the end of the study (two weeks), there were no significant (P > 0.05) differences in length (6.0 ± 0.1 cm), weight (3.2 ± 0.2 g), or survival (98.4 ± 1.4 percent). The results of these experiments on acute temperature and salinity tolerance indicate that juvenile pigfish can withstand rather large and abrupt changes in environmental conditions without significant impact on survival or growth. The adverse effects of the coldest water temperature tested could be mitigated by a simple, short-term accommodation. Therefore, pond-based grow-out of juveniles could be practical over much of the year. Conclusion All aquaculture producers are constrained by the economic realities of supply and demand, production costs and competition. Culture of marine baitfish presents an interesting opportunity for producers as demand often exceeds supply and, unlike most other aquaculture products, there is no competition from imports. The quality, availability and consistency that aquaculture provides would allow vendors to expand their live baitfish selection to the entire year and reduce pressure on natural fish populations. Pigfish, in particular, have several attributes that make them a viable candidate for marine baitfish culture on a commercial scale. Pigfish broodstock acquisition, husbandry and spawning of wild- caught and cultured fish has been well documented, and, in the case of cultured fish, eggs were obtained from pond-reared fish that were only one year old (data not shown). We have demonstrated that adult pigfish can be induced to mature and spawn in captivity, with normal and offset photoperiod cycling. This has resulted in more than 500 natural spawns (> 60 million eggs) during the last six years. Rearing protocols for pigfish have also been established, showing that the optimal temperature for growth and survival of larvae and juveniles is 24 C and 28 C, respectively, and the extent to which growth decreases at suboptimal temperatures (Faulk et al . 2018). An optimal feed ration equation was developed for pigfish to help producers minimize the time to market size, maximize growth and lower feed costs (Oberg et al . 2014). Although the overall size of the pigfish bait market is not well known, the research conducted to date indicates that a cultured product can be produced in as little as three months. Certainly, a commercial-scale operation would need to supply hundreds of thousands of bait-size pigfish for most of the year to be economically viable. This might be accomplished using pond culture, indoor recirculating systems or a combination of both. Production of pigfish eggs during the entire year would be an important step for commercialization and several groups of wild and F1 broodstock are being grown to that end. Advancements in marine baitfish culture could potentially provide a producer with a secondary or seasonal product along with an additional revenue stream. As aquaculture production continues to expand globally, identifying and capitalizing on niche markets such as marine baitfish production could provide a quality product while at the same time relieving pressure on wild stocks of certain coastal species. Acknowledgments This work was supported by Grant #NA14OAR4170102 to Texas Sea Grant College Program from the National Sea Grant Office (NOAA, US DOC), Grant # NA15NMF4270348 from the Saltonstall-Kennedy Grant Program (NOAA, US DOC), and Perry R. Bass Endowment in Fisheries and Mariculture at the University of Texas at Austin. All animal procedures were reviewed and approved by the Institutional Animal Care and Use Committee of the University of Texas at Austin. This is contribution number XXXX of the University of Texas Marine Science Institute. Notes Jeffrey B. Kaiser, Cynthia K. Faulk, Kathryn L. Thompson and Lee A. Fuiman. Fisheries and Mariculture Laboratory, The University of Texas at Austin Marine Science Institute, Port Aransas, Texas, USA 78373. 1 personal communication, Dr. Andrew Ropicki, from Texas Parks andWildlife Department data 2 Lone Star Outdoor News, 2017 References Darcy, G.H. 1983. Synopsis of biological data on the pigfish, Orthopristis chrysoptera (Pisces: Haemulidae). NOAA Technical Report NMFS 449. DiMaggio, M.A., J.S. Broach, C.L. Ohs and S.W. Grabe. 2013. Captive volitional spawning and larval rearing of pigfish. North American Journal of Aquaculture 75:109-113. DiMaggio, M.A., C.L. Ohs, J.S. 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