36 DECEMBER 2016 • WORLD AQUACULTURE • WWW.WAS.ORG into economic and social benefits, including new opportunities for fishermen and better management of common resources (Lorenzen 2008). Culture-based fisheries enhancement is a set of management approaches involving the release of cultured organisms to enhance or restore fisheries by increasing recruitment and spawning biomass (Lorenzen et al. 2013, Støttrup and Sparrevohn 2007). The practice began in the 1870s with hatchery releases of cod and plaice (Kitada and Kishino 2006), but these early attempts were hindered by limited understanding of the ecology and genetics of wild populations and by an emphasis on the quantity of fry released rather than on quantitative measures of success (Lorenzen et al. 2010, Leber 2013). This changed in the 1970s, when results of salmon restocking programs began to be published (Hager and Noble 1976). A renewed, responsible approach to stock enhancement emerged in the 1990s, with an increased focus on quantification of effects, significant progress in fisheries ecology, effective technologies for reproducing marine species in hatcheries, and improved methods of fish tagging (Blankenship and Leber 1995, Leber et al. 2004, Lorenzen 2008, Lorenzen et al. 2010, Lorenzen et al. 2012, Leber 2013, Lorenzen et al. 2013). This approach involves more than simply releasing hatchery-reared fish into the wild. The current approach requires a thorough understanding of the ecological processes affecting the fishery, close integration with fisheries management, broad inputs from stakeholders, serious consideration of the genetic constitution of released organisms (side bar 2), and quantitative goals and measures of success. Table 1 summarizes the stages and elements of a responsible approach to marine stock enhancement (Lorenzen et al. 2010). The concept has been implemented over the last two decades and there are now successful examples with salmon in Alaska (Stopha 2016), turbot in Denmark (Strøttrup et al. 2002), red sea bream and Japanese flounder in Japan (Kitada and Kishino 2006), white seabass in California (Gruenthal and Drawbridge 2012), and red drum in Texas (McEachron et al.1993), to name a few. The last two examples refer to sciaenid species related to totoaba. A restocking program for totoaba is sensible because hatcheryproduced juveniles could mitigate the lack of natural recruitment due to overfishing, habitat degradation, and direct removal of juveniles by shrimp trawlers. This would be a case similar to that of the role of salmon hatcheries in replacing fish runs lost to dams and reduction of habitat along the Pacific coast of North America. Given the current state of the totoaba resource, the fish could become extinct soon. A vigorous and comprehensive effort for totoaba restoration is necessary. Lessons can be drawn from the management of other high-value natural resources (side bar 3). Such a rebuilding effort would be difficult, but not impossible. It would require the political will to create effective institutional arrangements and multi-stakeholder agreements that include fishermen, aquaculturists, government, academics, and environmentalists. The means, scope, and goals of a comprehensive fishery management system would have to be determined, and incentives would have to be created for behaviors that contribute to positive outcomes. As a start, effective enforcement of existing regulations is essential. These should be coupled with measures to protect and restore the estuary of the Colorado River and adjacent nursery areas. Because the success of restocking programs depends on knowledge of the ecosystem and population dynamics, a proper assessment of the totoaba population should be conducted, ideally by the fisheries research arm of the Mexican government. With these efforts in place, a collaborative restocking program can be designed and implemented. Hatchery technology for totoaba is well developed and there are currently three geographically-diverse hatcheries (UABC in TABLE 1. Components of the responsible approach to marine stock enhancement (from Lorenzen et al. 2010). STAGE I: Initial appraisal and goal setting 1. Understand the role of enhancement within the fishery system. 2. Engage stakeholders and develop a rigorous and accountable decision-making process. 3. Quantitatively assess contributions of enhancement to fisheries management goals. 4. Prioritize and select target species and stocks for enhancement. 5. Assess economic and social benefits and costs of enhancement. STAGE II: Research and technology development, including pilot studies 6. Define enhancement system designs suitable for the fishery and management objectives. 7. Develop appropriate aquaculture systems and rearing practices. 8. Use genetic resource management to maximize effectiveness of enhancement and avoid deleterious effects on wild populations. 9. Use disease and health management. 10. Ensure that released hatchery fish can be identified. 11. Use an empirical process for defining optimal release strategies. STAGE III: Operational implementation and adaptive management 12. Devise effective governance arrangements. 13. Define a fisheries management plan with clear goals, measures of success, and decision rules. 14. Assess and manage ecological impacts. 15. Use adaptive management.
RkJQdWJsaXNoZXIy MjExNDY=