Greening of the Blue Revolution: Efforts toward Environmentally Responsible Shrimp Culture

Shrimp aquaculture has been criticized by organizations and individuals that charge the industry as being environmentally irresponsible. Publications such as Murky Waters by Goldburg and Trilett (1997) and the recent article in Nature by Naylor et al. (2000) identify a number of environmental problems associated with shrimp culture, including habitat destruction, water pollution, non-native introductions, collection of wild shrimp, and excessive use of marine protein in shrimp feeds. Although some of these charges have merit, others are not supported by scientific data. Clearly, it is in the industry\'s best interest to engage in environmentally responsible methods of production if long-term viability of the industry is to be achieved. Commercial farmers and researchers continue to develop and evaluate approaches to shrimp culture that protect both the natural environment as well as the shrimp culture environment. For example, by reducing water exchange rates, effluent discharge is minimized, thereby reducing nutrient and biological pollution in surrounding bays and estruaries. In addition, because influent water can serve as a vector for disease, the potential for pathogen introduction into the shrimp culture environment is reduced. The use of domesticated, specific pathogen free (SPF) shrimp eliminates the need for wild-caught shrimp and reduces the resk of transferring pathogens to non-infected areas. Also, domesticated shrimp can be selectively bred to improve economically important traits such as growth and disease resistence. Vegetable proteins can be use to replace or supplement marine proteins commonly used in shrimp feeds and this may relieve fishing pressures on marine resources, including pelagic fisheries. Vegetable-based diets would have the added benefit of being free of shrimp pathogens and would be less costly than diets containing marine proteins. Researchers at the Oceanic Institiute are developing shrimp production technologies that integrate several of the approaches identified above. Specifically, we have cultured SPF, genetically improved Pacific white shrimp (Litopenaeus vannamei) in a recirculating raceway designed for pathogen exclusion and have produced 4 kg of shrimp/m2 using 370 liters of water per kg of shrimp. In addition, we have evaluated vegetable-based diets and have achieved shrimp growth rates greater than 1 g per week. The heritability (h2) estimate for growth when shrimp were fed vegetable-based diets was high (mean half-sib h2 = 0.40 + 0.20 (+SE)), and it may be possible to select shrimp for rapid growth on these diets. Importantly, through advanced research, the shrimp farming industry will be able to expand into areas away from the coast with greater control against the spread of disease and without adversely affecting the environment.