26 MARCH 2022 • WORLD AQUACULTURE • WWW.WA S .ORG removal of urchins has not been possible due to the urchins typically possessing minor gonad development necessary for commercial marketing of gonads as uni. In response to this, aquaculture combined with fisheries have been used to enhance the urchin gonad quality and thereby the value of these wild urchins to incentivize their capture. Although sea urchin roe enhancement is not a novel concept, technical limitations to the activity are primarily related to the availability of macroalgae diets given seasonality and the propensity of urchin barrens to deplete kelp forests. Development of sustainable alternative diets for urchins is necessary for future commercial urchin aquaculture. A 2019 study aimed to enhance roe from purple sea urchins Strongylocentrotus purpuratus collected from California urchin barrens using four diet treatments, including giant kelp Macrocystis pyrifera, ogo Gracilaria pacifica, formulated commercial diet (Urchinomics), and an unfed control. During the 10-wk study, gonadal somatic index (GSI) was measured in a subset of five urchins from each replicate tank every two weeks. Baseline GSI at the beginning of the trial was < 0.5 percent. A commercially marketable GSI of 10 percent was reached most rapidly in the formulated diet treatment at 6 weeks, followed by ogo and kelp at 9 and 13 weeks respectively (Fig. 10). The relative short duration to culture purple urchins to a marketable gonad condition is promising, especially considering the variation in time to GSI score among the different diets. The variation in diet response indicates that there is significant scope for further husbandry and nutritional improvement. This preliminary examination of the feasibility of urchin ranching in California indicated the biological potential to develop urchin gonads using alternative diets with a view to restore kelp forests and develop a nascent aquaculture industry in California. Future research for roe enhancement of purple urchins should include a more thorough assessment of nutritional requirements and digestibility, as well as quantitatively assessing the resulting roe for important market characteristics including color, texture and taste. An economic feasibility is also required to determine the commercial potential of this aquaculture activity for restoring kelp forests. The potential of commercial aquaculture to be used to achieve a conservation goal and economic profitability is an uncommon opportunity and should be thoroughly investigated. The Role of Aquaculture in the Conservation of Amphibians at the San Marcos Aquatic Resources Center Justin Crow Although aquaculture has become an increasingly important tool for meeting the needs of a growing human population in a sustainable manner, it also plays a critical role in the conservation of at-risk species. Captive assurance and breeding colonies of amphibians have been established by universities, non-profits, zoological institutions and conservation agencies around the world. The International Union for Conservation of Nature and Natural Resources listed captive programs among the top response priorities relevant to amphibian conservation globally. The San Marcos Aquatic Resources Center, a US Fish and Wildlife Service facility, is an aquaculture facility dedicated to the support of federally listed species (Fig. 11). The mission of the Center is to provide support for and undertake research on endangered, threatened and species at risk. The Center maintains captive assurance colonies for multiple amphibian species, including the Texas blind salamander Eurycea rathbuni, San Marcos salamander Eurycea nana, Barton Springs salamander Eurycea sosorum (Fig. 12), and the Houston toad Anaxyrus (Bufo) houstonensis. Aquaculture-related activities for these species are inherent to this mission. Captive Rearing of the Endangered Orangeblack Hawaiian Damselfly and Reintroduction Attempts on Oʻahu William Haines, Katrina Scheiner, Kelli Konicek, Karl Magnacca and Cynthia King The damselfly genus Megalagrion is endemic to Hawaiʻi and includes about 25 species, many of which have suffered major declines due to habitat loss and the introduction of mosquito fish Gambusia spp. that prey on the aquatic immature stages (naiads) of damselflies. The once common orangeblack Hawaiian damselfly Megalagrion xanthomelas (Fig. 13) was thought to be extinct on Oʻahu until it was rediscovered in 1994 at Tripler Army Medical Center (TAMC). This small population occupies FIGURE 11. SMARC biologist tending to Barton Springs salamander captive assurance colony. FIGURE 12. Barton Springs salamander offspring developing at the SMARC.
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