42 SEP TEMBER 2022 • WORLD AQUACULTURE • WWW.WA S .ORG elements of production are limiting, the other resource is wasted. For example, if ponds are fertilized and filled and there is no fry available to stock them, the stocking window would be missed, resulting in wasted fertilizer, water, manpower and time. On the other hand, if eggs and fry are produced and an adequate number of ponds are not ready, then the eggs are wasted. The ability to reliably predict the frequency and magnitude of spawns based on lunar phase can help hatchery personnel plan ahead and synchronize these elements of production, thus fully utilizing natural, financial and seasonal resources. Notes Jessica Sannwaldt and Jennifer Butler, 302 Medical Dr., Lake Jackson, TX 77566 References Arnold, C.R., W.H. Bailey, T.D. Williams, A. Johnson and J.L. Lasswell. 1977. Laboratory spawning and larval rearing of red drum and southern flounder. Proceeding of the Annual Conference Southeastern Association of Fish and Wildlife Agencies 31:347-440. Bishai, H.M. 1960. The effect of water currents on the survival and distribution of fish larvae. ICES Journal of Marine Science 25(2):134-146. Cabrita, E., V. Robles and P. Herraez. 2009. Methods in Reproductive Aquaculture: Marine and Freshwater Species. CRCMarine Biology Series. CRC Press, Boca Raton, FL, USA. Celik, P. and I. Celik. 2011. Effects of lunar synchronization on the reproductive time of discus fish (Symphysodon sp) under controlled aquarium conditions. Journal of Animal and Veterinary Advances 10(7):890-893. Esteban, A.M, A. Cuesta, A. Chaves-Pozo and J. Meseguer. 2013. Influence of melatonin on the immune system of fish: A review. International Journal of Molecular Sciences 14:79797999. Gliwicz, M. 1986. A lunar cycle in zooplankton. Ecology 67:883897. Hernández-León, S., C. Almeida, L. Yebra and J. Aristegui. Benefits of Lunar Periodicity There were many reasons why fish mau have spawned in synchrony with lunar phases. Many fish displaying parental care for their young take advantage of the light of a full moon by exhibiting lunar periodicity and synchronizing their spawns with the full moon (Schwanck 2006, Taylor 1984). However, this is not the case for broadcast spawners, such as red drum. Synchronized spawning is advantageous for fish because it leads to strong genetic recombination. When several female fish respond to the same environmental conditions by releasing hormones and completing gametogenesis together, and when spawns occur in large aggregations, this permits a higher level of recombination (Johannes 1978). Another advantage to lunar-synchronized spawns could be utilization of the stronger tides associated with the lunar cycle (Johannes 1978). Red drum spawn offshore of Texas, in close proximity to nearshore passes. Shortly after eggs are spawned, tides, winds and currents assist young red drum recruitment into bays where they utilize food resources and habitat structure in this nursery ground through their sub-adult stage (Bishai 1960). Strong tides and currents also benefit eggs and fry by quickly dispersing them, making themmore difficult for predators to consume in large numbers. There are many other marine species that have life cycles synchronized with lunar cycles. Timing spawns with lunar phases is widely thought to be advantageous to the young, small fish because of a rise of planktonic food sources, inasmuch as many invertebrate zooplankton spawn with the lunar cycle (Gliwicz 1986, Hernandez-Leon et al. 2002). Understanding the effects of lunar periodicity on spawning behavior can help hatchery personnel make the best use of resources. If properly applied, this knowledge could help maximize production and increase efficiency. Aquaculture programs such as SCT that rely on volitional spawning and employ a semi-intensive strategy to produce fingerlings attempt to balance nursery pond preparation, including cleaning, filling and fertilizing, with egg and fry production. If either of these two FIGURE 2. Red drum spawning events during each lunar phase, 2013-2020. FIGURE 3. Red drum eggs spawned during each lunar phase, 2013-2020.
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