Kenya's cure to poverty and increased food production is Fish Farming

shrimp culture information site in Indonesian version

Provides a discussion forum and information on shrimp and prawn culture in Indonesia

The moderated, but continual development of the shrimp aquaculture in Mexico, in conjuction with municipal and agriculture effluents, in the last decade has created the first symptoms of negative environmental impacts, due mainly to the discharge of nutrients and organic matter into adjacent coastal waters. Similarly, the increasing impairment of coastal water quality resulting from the discharge of domestic, agricultural and industrial wastes into coastal waters has affected the aquaculture profitability in certain areas. The cumulative impact of the main anthropogenic sources of nutrients in the Mexican coastal states was estimated in 190 088 ton N yr-1 and 51 831 ton P yr-1. The input from shrimp aquaculture is only 1.5% and 0.9% of the main sources of nitrogen and phosphorus. This last input, though small, is related to local and adverse effects on coastal ecosystems. The introduction of management measures to mitigate the adverse environmental impacts of shrimp aquaculture development has now become necessary and urgent.

The present work is a first attempt to document the latest reports on the occurrence of algal blooms in shrimp farm ponds worldwide. Particular emphasis is placed on discussing the relation of algal blooms with nutrients, with special reference to the northwest of Mexico. Typically, shrimp pond waters are enriched with organic matter and nutrients whose concentrations depend mostly on the management (i.e. higher stocking densities, water use, food and fertilizers). Generally, more intensive culture systems produce higher loads of nutrients in their discharge (e.g. N and P). Nitrogen and P concentrations vary in pond waters; N/P ratio ranges from 1.1 to 67 with values being more frequently between 1.1 and 6.8. Such variations are closely related with the cycling and supply of nutrients in the ponds. In shrimp farms located in NW Mexico, phytoplankton abundance varies widely, having a higher abundance in advanced stages of the culture cycle. In the most common pond types (intensive and semi-intensive), Synechocystis diplococcus (cyanobacteria) was the dominant species (>88.9%), followed by Peridinium trochoideum (Scrippsiella trochoidea) and eventually Prorocentrum minimum and Gymnodinium spp. (dinoflagellates). The numerous occurrences of large blooms of dinoflagellates and other functional groups such as cyanobacteria, diatoms, chlorophytes and flagellates mean economic losses for farm industry on account of shrimp mortality or growth diminution due to poisoning, anoxic or mucus production effects, in which shrimp were mortality provoked in different regions: in China, the dinoflagellates Alexandrium tamarense (Gonyaulax tamarensis) and Gymnodinium; in Malaysia, the raphidophyte Hornellia (Chattonella) and the dinoflagellate Pyrodinium bahamense var. compressum; in Vietnam, the diatom Nitzchia navis-varingica; in Ecuador, the dinoflagellate Gyrodinium instriatum; and in NW Mexico the cyanobacteria S. diplococcus, Schizothrix calcicola, and the dinoflagellates P. minimum, and lastly Gymnodinium catenatum from supply waters.