An overview of L. vannamei shrimp aquaculture

Litopenaeus vannamei is the most commonly cultured shrimp in Latin America and Southeast Asia, representing over 90 % of total shrimp production. India with its 8,118 km of coastline and 1.24 million Ha of brackish water area is the second shrimp producer in the world, with Andhra Pradesh being India’s largest vannamei farming area. Andra Pradesh, situated on the southern coast of the country, has 974 km of coastline and 175,000 Ha of brackish water. Andhra Pradesh has gradually increased its share in total marine exports of the country, with the United States and Vietnam as the main export markets.

Currently, the state’s L. vannamei aquaculture is facing different issues and challenges to achieve sustainability related to diseases outbreaks, lack of availability of quality seed, high feed costs, unauthorized farming, international price fluctuations, less demand in the domestic market, and others. If farmers implement Better Management Practices (BMP) and biosecurity in L. vannamei culture supported by the Government policy measures then sustainability can be achieved. This article discusses the present culture practices, major problems, future perspectives and suggestive measures for sustainable L. vannamei farming in Andhra Pradesh.

A brief history of L. vannamei:

Shrimp farming started as an initiative of the Government of India (GoI) with a study of brackish water fish farming in the late 1970’s. Due to the economic benefits from shrimp farming, the culture of Penaeus monodon developed rapidly during the early 1990’s. The intensification of culture systems and the lack of biosecurity led to disease outbreaks of White Spot Syndrome Virus (WSSV) in 1994. The P. monodon culture almost collapsed in the late 1990’s so in 1999 the fresh water prawn, ‘scampi’ Macrobrachium rosenbergii was introduced as an alternative to P. monodon. The 1990’s are well known as the “era of virus disease” and Andhra Pradesh’s shrimp aquaculture was not the exception.

In 2001- 2002, fresh water prawns faced severe disease outbreaks that affected the state’s production significantly. This is when the Litopenaeus vannamei was proposed as an alternative species due to their disease resistance and tolerance to high stocking densities, low salinity and temperature, as well as their high growth rate. At the same time a risk analysis was carried out by the Central Institute of Brackishwater Aquaculture (CIBA) and National Bureau of Fish Genetics and Resources (NBFGR) with the aim of evaluating the feasibility of the introduction of this new species.

After the experimental studies and due to the constant pressure of growers and traders for the introduction of L. vannamei due its potential in the export market, in 2009 the Coastal Aquaculture Authority (CAA) approved vannamei culture through import of Specific Pathogen Free (SPF) brood stock and strict regulatory guidelines. In order to reduce the risk of adverse effects of the introduction of this exotic shrimp, the Rajiv Gandhi Centre for Aquaculture (RGCA) created the “Aquatic Quarantine Facility of L. vannamei” (AQF) at the behest of Ministry of Agriculture, which is a state-of-the-art facility located in Chennai, Tamil Nadu for quarantine of L. vannamei broodstock imported to India.

L. vannamei in Andhra Pradesh 

For over 25 years, the P. monodon was the mainstay of Indian aquaculture but since L. vannamei’s introduction in 2009, its production and culture area has gradually decreased while L. vannamei has increased.

Potential for development of L. vannamei culture

The production of L. vannamei shrimp is concentrated in East Godavari, West Godavari, Krishna, Prakasam and Nellore state districts. Andhra Pradesh produces more than half of the country’s farmed shrimp and still has a lot of potential to exploit this resource by expanding culture to low salinity waters and through the rehabilitation of abandoned farms in Krishna district. Currently, Srikakulam (the northernmost district of the Andhra Pradesh Coastline) is considered as the ‘sunrise’ of the state’s shrimp farming.

Nursery, culture and feeding practices

The CCA recommends a density of 60 shrimp/m2 but depending on the pond and soil conditions as well as the farmers’ experience the culture densities vary, occasionally reaching 2,000,000 to 6,000,000 Post Larvae (PL) per hectare. Prior to stocking, the pond is tested in order to maintain a pH of 6.5-7. The PL 10 -12 is regularly stocked in high salinities with more than 10 ppt, while PL 15 is stocked when the salinity is low. During the production cycle the water temperatures are maintained between 24-32ºC and the Dissolved Oxygen at 4-5 ppm. The culture cycles in the region range from 90 – 120 days and producers regularly have 2 cycles per year, with stocking in February-March and later in September-October. Shrimp of 17 – 19 grams are considered as a marketable size for the species. Currently the farmers are practicing partial harvests after 60 – 70 days of culture to overcome the slower growth rates of L. vannamei after reaching a size of 19 grams and the increase of operational cost as the days of culture increase. According to the Department of Fisheries of Andhra Pradesh the average production per hectare in the state is 3,000 to 4,000 kg.

As a consequence of the intensification of L. vannamei culture systems in recent years, higher Feed Conversion Ratios (FCR) have been registered, ranging from 1.5:1 to 1.8:1. The feeding frequency in the state is typically 2-4 times per day.

Challenges for sustainable L. vannamei farming

The growth of L. vannamei in the state has been impressive but for further expansion and sustainability the main issue is the lack of availability of quality seed from Specific Pathogen Free brood stock. By 2015, in Andhra Pradesh the CAA has given permission to 192 L. vannamei hatcheries and the Government of India permitted 17 hatcheries for nauplii rearing in facilities outside the jurisdiction of the CAA. For the last couple of years, L. vannamei farms started to develop their own brood stocks from grow out ponds and began producing seed; these seed are sold in the market as SPF and due to the lack of proper testing facilities is impossible for farmers to known the real quality of the seeds. Disease outbreaks are another issue that L. vannamei farming is facing nowadays; they have increased the economic risks and slowed the industry’s development. The White Spot Syndrome Virus (WSSV) and Yellow Head Virus (YHV) resulted in catastrophic losses in Asian and Latin American shrimp farms. However, no major disease outbreaks have been registered in Andhra Pradesh.

WSSV, White Faeces Syndrome (WFS), Loose Shell Syndrome, Black Gill Disease (BGD), Running Mortality Syndrome (RMS) and White Muscle Disease (WMD) are the most common diseases that have affected L. vannamei in Andhra Pradesh. And most recently, Enterocytozoon hepatopenaei (EHP) which does not cause mass mortalities but has been shown to reduce growth. Globally, the feed prices are gradually increasing as a consequence of the rise of raw materials and fishmeal price hikes and Andhra Pradesh shrimp producers are resenting this situation, reflected in the increment of their operational costs.

In Andhra Pradesh, small farm holdings are the most common. Price fluctuations and the lack of information on international prices and demand have generated economic losses for small-scale producers. The uncertainty of market prices has made farmers unable to buy high quality feed, which is very costly. In addition, the quality of more economical feed is often unknown and has to be tested but there is a dearth of technical manpower and laboratories.

Suggestions for achieving sustainability

The shrimp farming industry in the region has been consolidated over the years, but to achieve sustainability it is necessary to increase the Aquatic Quarantine Facilities (AQF) and create more SPF brood stock and nauplii rearing centers. At the same time, it is important to prevent the operation of unauthorized hatcheries and nauplii rearing centers. It is also fundamental to generate protocols and guidelines for probiotic use in soil, water and feed; as well as promote the implementation of best management practices and biosecurity in shrimp culture. The installation of reservoir ponds in L. vannamei farms should be a must, as well as effluent treatment. The government should incentivize the rehabilitation of abandoned shrimp farms and expansion of culture areas as well as promote the development of alternate species with culture systems and hatcheries for mud crabs, sea bass and cobia. Techniques for reducing bacterial loads in shrimp culture systems should be addressed, among other topics.

The Andhra Pradesh L. vannamei aquaculture sector is characterized by small-scale farms, therefore it is important to organize shrimp producers into Farmer Producer Organizations to provide technical support and training in Best Management Practices and Biosecurity, as well as information about the national and international market.

Conclusions

The potential of shrimp culture in Andhra Pradesh is extraordinary; it generates a great number of direct and indirect jobs in the region, represents a great opportunity for rural development and brings a significant economic impact. Thus, it is important for all shrimp farmers to practice responsible aquaculture by only purchasing seed from authorized hatcheries, implementing strict biosecurity protocols and following strict quarantine measures and best management practices in culture systems. This way crop losses will be reduced, as well as the risk of disease outbreaks. Andhra Pradesh has the possibility to become an aquaculture hub in India, that’s the reason why the State government has considered incentives and subsidies to foment aquaculture and its sustainability.