Comparison of resource use for farmed shrimp in Ecuador, India, Indonesia, Thailand, and Vietnam

Shrimp farming has been widely criticized for excessive use of various resources and especially for coastal wetlands as farm sites. The purpose of this study was to assess the amounts of land, water, energy in fuels, and wild fish for fishmeal and fish oil in feeds required per ton of harvested, farmed shrimp in five countries producing most of the shrimp destined for the international market. Compared to Litopenaeus vannamei, black tiger shrimp Penaeus monodon required more land, a greater amount of water, but less energy per ton of shrimp.

Although comparatively small differences in average uses of these primary resources were found among countries, the large variation which was noted among farms in each country suggests that resource use could be improved considerably.

The most negative environmental impacts of shrimp farming and other types of aquaculture result from use of resources at the farm level and in acquisition of the resources themselves (embodied effects). Besides, feed use essential for semi-intensive and intensive production is a major source of resource use and the main reason for pollution by pond effluents.

In an effort to obtain a better knowledge of resource use in shrimp farming, estimates of land, water, energy, and wild fish use have been made for farmed shrimp in Ecuador, India, Indonesia, Thailand, and Vietnam, the five major farmed shrimp exporters. In addition, the benefits to land use of intensification of pond yields have been assessed.

“The purpose of this report is to compare resource use among the five countries for whiteleg shrimp (Litopenaeus vannamei) farming and for farming of black tiger shrimp (Penaeus monodon) in the four Asian countries.”

The resource use data for Ecuador, India, Thailand, and Vietnam have been published, and a summary of the data for Indonesia was presented in Juárez et al. (2021). In the present comparison, we recalculated the resource data from the original survey information using the updated embodied resource use coefficients.

Resoruse use for L. vannamei farming

Average area of individual production ponds was much greater in Ecuador than in Asia. India had larger ponds than Indonesia, Thailand, and Vietnam which did not differ in average pond area. Average pond depth ranged from 1.19 m in Indonesia to 1.49 m in Thailand with considerable overlap in the statistical comparison.

The use of deeper ponds is beneficial where mechanical aeration is applied as a means of reducing bank and bottom erosion which leads to higher total suspended solids and turbidity concentrations in pond effluent. All of the Asian farms in this comparison used aeration in L. vannamei ponds, and 46% of Ecuadorian farms used aeration in some or all ponds. The percentage of farms using water exchange was greatest in Ecuador and Indonesia with 87% and 90%, respectively.

Yields in Ecuador and India were similar, even though only about half of the Ecuadorian farms (46.5%) applied mechanical aeration. In India, Thailand, and Vietnam where the number of crops per year were relatively similar and all farms used aeration, there was a general increase in production with greater aeration.

“Feed was used at all L. vannamei farms in the five countries. Feed typically contained around 35% crude protein and it was applied three to five times daily.“

Amendments used in ponds include liming materials for neutralizing bottom soil acidity, fertilizers for stimulating primary productivity, chemicals for disinfection and shrimp disease control, and various products for water quality improvement.

Total land use ranged from 0.37 ha/t in Indonesia to 0.52 ha/t in Vietnam. Indonesia had the lowest land use, and no differences were found among the other countries.

Most water use was for brackish water or seawater applied to ponds, and reshwater use, other than for drinking, ice making, and sanitation purposes which was not determined, was the result of embodied water in fuels, feed, and amendments (mainly in feed). In Ecuador, where diesel fuel of lower embodied energy content than electricity was the primary fuel, embodied energy comprised 38.4% of total energy use.

Wild fish use for fishmeal and fish oil in feeds was greatest in Ecuador (0.89 t/t) because of the higher wild fish coefficient for feed than in Asian countries.

Resourse use in P. monodon farming

The results reveal considerable differences in average production pond areas on farms, stocking rates, differences in feed use, water exchange, and aeration.

The small feed inputs in Indonesia resulted in a low FCR because much of the production apparently was the result of natural food. Water use was especially great in Indonesia where it was applied by tidal action not requiring pumping. Water exchange was not practiced in Thailand, and fewer farms in Vietnam used water exchange than was the case in India.

In India and Vietnam, wild fish use was greater than observed in L. vannamei farming. This was mainly the result of a high wild fish coefficient for P. monodon feed. The lower wild fish use in Indonesia was caused by greater reliance on natural food and small inputs of feed.

DISCUSSION

The production of L. vannamei in Ecuador appears to be shifting from semiintensive culture which relies on feed to intensive culture in which both feed and mechanical aeration are applied as done in Asia. It is clear from this comparison that much greater intensification of L. vannamei production is possible without resorting to biofloc technology in ponds or intensive tank culture.

Water exchange remains a common practice in L. vannamei farming, particularly in Indonesia and Ecuador. Farmers using water exchange may have had confidence in stocking more shrimp in which case the difference in yield may be unrelated to water exchange. Water exchange should not be promoted with exception of cases of excessive salinity.

The longer the hydraulic retention time (lower exchange rate) in ponds, the greater the opportunity for reduction in concentrations of dissolved organic matter, ammonia nitrogen, and soluble phosphorus through natural processes. Nitrogen, phosphorus, and silicate fertilizers are widely used in Ecuador in an effort to promote phytoplankton and especially diatoms.

Although nitrogen and phosphorus fertilizers may encourage phytoplankton, they should only be used in ponds with feeding in the early weeks of grow-out or when waters become clear and underwater aquatic plant infestations are likely to occur. Magnesium and potassium may be beneficial in low-salinity water (<10 g/m3 ), but these mixes usually are not necessary in water of greater salinity.

The main limitation of disinfection in Ecuador probably is the high cost of treating ponds containing large volumes of water. Chlorine compounds are common disinfectants in shrimp farming. Chlorine treatment of municipal drinking water containing dissolved organic matter can result in formation of trihalomethanes which are suspected carcinogens.

Probiotics are commonly used in shrimp culture worldwide, but the benefits to water quality are questionable.

Piscicides such as saponin can be effective in eradication of wild fish from shrimp ponds. Screens on water inflow and outflow structures reduce the number of wild fish introduced.

“Amendments, if used properly, will not harm shrimp, even though they may be ineffective for the intended purpose. Nevertheless, amendments add to production cost.”

Assessment of land and water use is problematic in shrimp farming. The coastal land is considered to represent greater biodiversity than does crop and. Moreover, when a portion of shrimp is eaten, a portion of some other meat choice likely is foregone. Land is required for production of the other meat animals, so increasing crop land for shrimp feed likely does not increase total land use for animal feed.

Water for operating shrimp farms is taken mainly from brackish water in estuaries or from the sea. Such water is not useful for most human needs, and it is not considered a part of the supply of water available for human use. Freshwater use in shrimp farming consists of embodied freshwater in feeds, other substances used in producing shrimp, and water used for drinking, ice used to chill harvested shrimp, and sanitary purposes. These uses consume much less freshwater than the amount of saline water used for farm operations.

“When compared with L. vannamei production, feed-based P. monodon production appears to use more land, similar quantities of water, somewhat less energy, and more wild fish than does feed-based production of L. vannamei.“

The annual pond yield for P. monodon did not approach the levels observed for L. vannamei.

Resource use: shrimp versus chicken, pork, and beef

Whiteleg shrimp required slightly less land per ton of edible crude protein than did broiler chickens which required less land for this purpose than did pigs and beef cattle. Shrimp required less freshwater per ton of edible crude protein than did any of the traditional, terrestrial meat animals. But shrimp used a large amount of saline water not required in production of the other meat proteins.

The higher energy requirementfor shrimp production, and presumably for most aquaculture species that use continuous water exchanges (e.g. raceway production systems) recirculating aquaculture systems or considerable aeration, relates to the difficulty in maintaining the dissolved oxygen concentration at a suitable level in water.

“From a nutritional standpoint, the proximate composition of shrimp is within the ranges of the three most common terrestrial meat sources. The concentrations of macro- and micro-nutrient minerals and vitamins in shrimp meat fall within the ranges found for other meats.“

The cholesterol concentration in shrimp is about twice that of chicken meat, beef, and pork. Although cholesterol is considered a factor contributing to cardiovascular disease, shrimp meat provides about 180 mg/100 g combined of the omega-3 fatty acids, eicosapentaenoic and docosahexaenoic, of cardiovascular benefit.

Possible applications of resource use data

Great improvements would result if the less efficient farmers would improve to the average found in the surveys of the five countries and greater improvements obviously are possible.

Farmers desiring to participate in shrimp certification must be willing to modify their production practices if necessary to comply with certification standards. However, the certification programs should give more consideration to the efficiency with which resources are used in shrimp production.

This type of data collection may not result in publication of high-impact journal articles, but it is necessary for spotting trends, identifying problems before they become widespread, and more recently, challenging assumptions made through theoretical modelling.

This is a summarized version developed by the editorial team of Aquaculture Magazine based on the review article titled “COMPARISON OF RESOURCE USE FOR FARMED SHRIMP IN ECUADOR, INDIA, INDONESIA, THAILAND, AND VIETNAM” developed by: CLAUDE E. BOYD, ROBERT P. DAVID, AARON A. MCNEVIN. The original article was published on OCTOBER 2021, through AQUACULTURE FISH AND FISHERIES under the use of a creative commons open access license. The full version can be accessed freely online through this link: https://doi.org/10.1002/aff2.23