34 DECEMBER 2016 • WORLD AQUACULTURE • WWW.WAS.ORG Once broodstock spawn, fertilized eggs float to the surface and can be harvested with skimmers and concentrated into collectors. Totoaba tend to group-spawn at night, and successful spawning results in egg collectors with millions of eggs. Fertilized eggs are transferred from egg collectors to hatching tanks and eggs typically hatch after 24 hours at 23 C. After hatching, larvae are transferred to rearing tanks. Larviculture requires strict management, water filtration, and disinfection, so recirculating systems are also used. During larval stages (Fig. 7), live feeds such as rotifers and Artemia are cultured separately, enriched, and fed to larvae multiple times per day. Artemia are the final live feed, after which larvae are transitioned to commercial weaning diets. Once fully weaned, fingerlings are fed solely on fine crumbled feeds of the appropriate size for their mouth gape. Larvae remain in these tanks for 30 days, until they are fully weaned and hardy enough to be transferred to fingering tanks. In these finishing tanks, they are grown to 10-50 g individual weight as required for subsequent grow-out in sea cages or for transfer to appropriate locations for stock enhancement. Totoaba fingerlings produced in the hatchery are transferred to marine cages for grow-out after they reach 10 g. Transfer is done carefully to avoid excessive stress from handling or from sudden changes in temperature, pH, or water depth. Spherical and submersible Aquapod® cages with volumes of 1,600, 3,600, or 4,800 m3 are used for grow-out (Fig. 8). Initially fry are pumped into nursery nets placed inside the Aquapod® cages, where they can be monitored and fed intensively. Once they reach 250 g average weight, they are released from nursery nets to have access to the full volume of the cages. Feeding is done remotely with an automated delivery system and video monitoring. A commercial marine fish ration with 46 percent protein and 13 percent fat is fed one to three times per day. Figure 9 depicts the growth of a batch of totoaba The mixed blessing of high-value natural resources High-value natural resources such as ivory, gemstones, and precious metals can be sources of economic prosperity when they are well-managed, bringing higher standards of living and facilitating regional prosperity. The inverse result is unfortunately common and well known to economists as part of the “resource curse” or the “paradox of plenty.” The general differences in management and governance between these two opposite outcomes deserve consideration as applicable to cases such as the totoaba swim bladder. In general, where high-value resources result in socioeconomic degradation, it is because their exploitation is controlled by outsiders who syphon revenue out of local communities under the neglect or complicity of unaccountable and corrupt authorities. The local population is viewed mostly as a source of cheap labor. Regulations tend to be non-existent, overly complex, or applied selectively. Exploitation of these resources often results in their depletion and related environmental destruction. Products are commoditized and their origin is disguised. These so-called “conflict resources” are often coupled to social unrest, insecurity, and/or organized crime. High-value resources have better chances of fostering prosperity when managed under cooperative partnerships between local stakeholders and accountable institutions with agendas focused on the aspirations and circumstances of local community members. In this approach the rules and regulations are fair, and not only followed, but also enforced by the users. Decision making is participatory, focused on local people, and based on their needs and objectives. A significant portion of the revenues stays in the local communities and is applied with transparency to their improvement, notably in the form of investments in people and projects that create future wealth, livelihoods or human well-being. The resource is managed with integrity and with environmental, economic, and social sustainability in mind. Products are branded and proudly identified as to their origin. FIGURE 5. The Earth Ocean Farms totoaba hatchery in La Paz, Baja California Sur, Mexico. EOF photo by Fernando Cavalin. FIGURE 6. One of Earth Ocean Farm’s 80-m3 totoaba broodstock maturation tanks. Note cover to allow photoperiod manipulation, windows to observe fish behavior, and water recirculation equipment on the right. EOF photo by Lorenzo Juarez.
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