The use of antibiotics and other chemicals in controlling shrimp pathogens become ineffective as the strains grow more resistant to these chemicals. Moreover, the bacterial pathogen (Vibrio harveyi) produced biofilm coating that protects it from dying and disinfection procedures that are followed during pond preparation. Biological control is being considered as an alternative means of preventing shrimp disease outbreak. The main principle behind biological control is to enhance the growth of beneficial microorganisms which serve as antagonists or target pathogens.
The growth, mortality, and recruitment pattern of Penaeus californiensis were investigated using tail length (TL)-frequency data obtained from the Gulf of Guayaquil shrimp population. Computer-based methods of tail-frequency analysis Compleat ELEFAN software were used. Results obtained gave relatively high growth and mortality estimates for both males and females. The recruitment pattern indicated two pulses annually, one significantly larger than the other.
Historically, land and water management within many coastal deltas has focused on the exclusion of saline water flows that move upstream from the coast. However, this approach fails to recognize the diversity of rural livelihoods and ecosystems in coastal deltaic areas, the environmental consequences of altering natural saline water flows and the emergence of new activities such as shrimp farming that require brackish water.
A discussion is presented on the 2 approaches - holism and reductionism - in the study of environmental sciences, making reference to various projects presently being conducted by ICLARM and its collaborators using the holistic approach. Schematic representations are given of ICLARM's FISHBASE, the ECOPATH II model of the Peruvian upwelling ecosystem and submodels which may be incorporated in large simulation models of the upwelling system, and also material flows in a rice-fish/shrimp integrated farming systems of the Mekong Delta, Vietnam.
A modification of the Schaefer surplus-production model was used to account for environmental induced variations of shrimp (Penaeus vannamei) catch in northern Peru. Based on time series of catch, effort, river discharge and sea surface temperature, fluctuations in catch of shrimps are explained and discussed with respect to multiple level of carrying capacity and hence different maximum sustainable yields.
Technology for effective and fast diagnosis of animal diseases is essential for developing aquaculture management strategies. This paper reviews the conventional techniques for shrimp disease diagnosis and discusses the emergence of nuclei acid probes and polymerase chain reaction (PCR)-based kits as powerful tools for rapid and accurate detection of shrimp diseases.
A procedure is proposed by which recruit numbers and parental biomass of shrimps stocks can be derived, given a series of catch per effort data and estimates of a few ancillary variables. In the Gulf of Thailand, shrimp recruitment decreased with decreasing egg production, but increased with decreasing total (mainly fish) standing stock. The net result of these counteracting effects was an overall increase in shrimp recruitment, attributable to a greatly reduced prerecruit mortality.
The marine fisheries of Trinidad and Tobago are mainly artisanal and involve about 8,000 fishers. The main fishing gear used are the gillnets, the troll, the shrimp trawl, the fishpot and the industrial longline. Landings total approximately 14,000 t annually with Scomberomorus brasiliensis, shrimps and sharks being the most abundant in the landings. Assessment studies indicate overfishing and inferior marketing is an important issue. Underexploited resources include clupeiods, deep shell and slope resources, and lobsters. The shrimp trawl and longline by-catch are not fully utilized.
As a result of increased population growth, the attraction of high profits from shrimp culture and ineffective mangrove forest management, a number of serious environmental problems exist in Ngoc Hien District, Minh Hai Province, Vietnam. These environmental problems are highlighted in this article.
The BayFish-Bac Lieu model presented in this chapter is a Bayesian model that aims to identify optimal water control regimes and trade-offs between water uses in order to improve management of water-dependent resources in the inland coastal area of Bac Lieu Province, Mekong Delta, Vietnam. The model was developed between 2004 and 2007 and integrated local databases, outputs from the Vietnam River Systems and Plains (VRSAP) model and stakeholder consultations.