The growth and survival of Penaeus vannamei postlarvae was measured at temperatures of 20, 25, 30 and 35 °C and salinities of 20, 30, 35, 40 and 50%.. Groups of 30 animals were used in each combination of conditions, in triplicate. The results clearly show that juveniles of this species have their best survival between temperatures of 20 and 30 °C and salinities above 20%.. Best growth was obtained between temperatures of 25 and 35 °C, with little difference being noted among salinities. Survival and growth coincide best at around 28 to 30 °C and 33 to 40%.. Calculated overall production was shown to be best in these conditions. The results demonstrate a high coincidence between the experimentally determined optimum conditions for production and the prevailing conditions in the coastal environment from which the animals originated.

The effects of salinity and temperature on the growth and survival rates of juvenile white shrimp, Penaeus vannamei, Boone, 1931

Abstrcat Immunostimulants are valuable for the prevention and control of fish diseases in aquaculture.Several immunostimulants such as polysaccharide and micronutritional factors and their effective mechanism are reviewed, meantime, existing problems in immunostimulant application and future research tendency are described.

Current Research Status of Fish Immunostimulants

In Mekong Delta, viral infection, including white spot syndrome virus (WSSV), monodon baculovirus (MBV), heptopancreatic parvovirus (HPV), infectious hypodermal and hematopoietic necrosis virus (IHHNV) and gill-associated nidovirus (GAV) frequently infect cultured shrimp starting at the postlarvae stage. These viral infections cause high mortality of shrimp and affect the farmer’s income. Previous studies mainly focused on the detection, transmission and genetic variation of the pathogens, but few studied the correlation between disease occurrence and other factors, including pond conditions, culture technique and management. Three studies analysed the association of culture factors with the WSSV disease incidence determining risk and potential protective factors in freshwater rice-shrimp systems, and brackish water polyculture and monoculture of black tiger shrimp (Penaeus monodon). Studies on the risk and protective factors in the odd of viral diseases in rice-shrimp rotation were lacking, while in 2011 the Early Mortality Syndrome (EMS)/Acute Hepatopancreatic Necrosis Syndrome (AHPNS) caused the great losses of cultured shrimp in Mekong Delta. This study was carried out to describe the culture status of shrimp in Mekong Delta and to identify the risk and/or protective factors that related to disease incidences in black tiger shrimp cultured in 2011. Through interviews, 58 variables collected from 191 farmers (64: rice-shrimp rotation and 127: intensive system) in Soc Trang and Bac Lieu Provinces, Viet Nam. The data were analysed in two steps of variable reduction to increase model stability and binary logistic regression to identify the risk and/or protective factors. The results showed that the risk factors were pond size (entire dataset, rice-shrimp rotation and intensive culture), settling pond (entire dataset), period of pond dry (entire dataset), stocking density first (rice-shrimp rotation), and stocking density second (rice-shrimp rotation). The potential protective factors were the mode of water intake (entire dataset), water level (entire dataset and rice-shrimp rotation), water quality parameters before stocking (entire dataset), and fry test (rice-shrimp rotation).

Virus diseases risk-factors associated with shrimp farming practices in rice-shrimp and intensive culture systems in Mekong Delta Viet Nam

The continuous development of world aquaculture demands new strategies and alternatives aimed to achieve sustainability. The use or microorganisms in aquaculture has greatly evolved during the last two decades. From being considered as a potential threat, during the last years, they have been used as probiotics and inclusively as food source for fish and crustacean. The microbial-based systems represent one of the most viable strategies to achieve a sustainable aquaculture. In short, these systems are based on the promotion of microbial proliferation, either autotrophic or heterotrophic microorganisms; these microbes are expected to use, recycle and transform the excess of nutrients from faeces, dead organisms, unconsumed food and diverse metabolites into biomass, which would be further consumed by the cultured organisms. Successful results on using microbial-based systems have been documented around the world; however, there are key aspects to consider and yet to experiment before a system could be implemented. Some of those aspects are analysed in this manuscript, while new advances in the use of microbial-based systems and recommendations are also presented.

Microbial-based systems for aquaculture of fish and shrimp: an updated review

Parasitic infections are ubiquitous in wildlife, livestock and human populations, and healthy ecosystems are often parasite rich. Yet, their negative impacts can be extreme. Understanding how both anticipated and cryptic changes in a system might affect parasite transmission at an individual, local and global level, is critical for sustainable control in humans and livestock. Here we highlight and synthesise evidence regarding potential effects of ‘system changes’ (both climatic and anthropogenic) on parasite transmission from wild host-parasite systems. Such information could inform more efficient and sustainable parasite control programmes in domestic animals or humans. Many examples from diverse terrestrial and aquatic natural systems show how abiotic and biotic factors affected by system changes can interact additively, multiplicatively or antagonistically to influence parasite transmission, including through altered habitat structure, biodiversity, host demographics and evolution. Despite this, few studies of managed systems explicitly consider these higher-order interactions, or the subsequent effects of parasite evolution, which can conceal or exaggerate measured impacts of control actions. We call for a more integrated approach to investigating transmission dynamics, which recognizes these complexities and makes use of new technologies for data capture and monitoring, and to support robust predictions of altered parasite dynamics in a rapidly changing world.

https://royalsocietypublishing.org/doi/pdf/10.1098/rstb.2016.0088

Global change, parasite transmission and disease control: lessons from ecology

Stocking density is an important factor in cage aquaculture of finfish. Effects of high stocking density (35 fish cubic m−1) on a range of biochemical and immunological parameters in Asian seabass reared in open sea floating net cages were compared to fish held in relatively low density (15 fish cubic m−1). The results revealed that chronic stress due to high stocking density induced variations in most of the parameters studied as evidenced by increased cortisol and glucose levels and decreased activity of lysozyme, myeloperoxidase and complement. Production of reactive oxygen species, total leucocyte count and total serum protein were also decreased, whereas anti-protease, alkaline phosphatase and acid phosphatase activities were increased in high stocking-density group when compared to low stocking-density group. Effects of chronic stress due to high stocking density were discussed in relation to variations in these parameters.

Chronic stress due to high stocking density in open sea cage farming induces variation in biochemical and immunological functions in Asian seabass (Lates calcarifer, Bloch)

Evaluation of immune response and resistance to diseases in tiger shrimp, Penaeus monodon fed with biofilm of Vibrio alginolyticus

Cobia (Rachycentron canadum) has been considered as a potential species for aquaculture because of its fast growth and commercial value. As a consequence of successful spawning and seed production, there has been a significant demand for cage farming of cobia in India (Philipose et al. 2013). Not many reports are available on diseases of cage-farmed cobia. Globally, mortality due to pasteurellosis in cage-cultured cobia caused by Photobacterium damselae subsp. piscicida has been reported (Liu, Lin & Lee 2003). Vibriosis caused by Vibrio alginolyticus, V. harveyi, V. parahemolyticus and V. vulnificus has also been responsible for mortalities in cage-cultured cobia (Rajan et al. 2001; Liu et al. 2004).

Photobacterium damselae subsp. damselae was originally isolated from the skin lesions of damsel fish, Chromis punctipinnis (Love et al. 1981). Subsequently, diseases caused by this pathogen have been reported in several cultivable fish species like seabream (Vera, Navas & Fouz 1991), eel (Ketterer & Eaves 1992), turbot (Fouz et al. 1992), ovate pompano (Zhao et al. 2009) and Asian seabass (Kanchanopas-Barnette et al. 2009). Infection caused by P. damselae subsp. damselae has also been recorded in marine mammals like dolphins (Fujioka et al. 1988) and several wild fish species (Han et al. 2009). Pathogenicity of this bacterium in several marine fish species and humans has been reviewed (Rivas, Lemos & Osorio 2013a). There have been no reports on mortality caused by this pathogen in cobia. This study was envisaged with the objectives to describe the disease epizootic caused by P. damselae subsp. damselae in cage-farmed cobia and characterize the pathogen.

First report of isolation and characterization of Photobacterium damselae subsp. damselae from cage‐farmed cobia (Rachycentron canadum)

An investigation was undertaken to study the fluctuations in the water quality parameters in a marine fish cage culture site offKarwar during the period 2009-2011. Two stations viz., one from cage site (Station 1) and the other away from the cage site(Station 2) were selected for the study. Water samples were collected at weekly intervals. Temperature of Station 1 variedfrom 28.5 ± 0.89 oC to 32.5 ± 1.04 oC during the first crop of Asian seabass culture in 2009-10 and it ranged between 26.7± 0.83 to 32.5 ± 0.79 oC during the second crop of seabass culture in 2010- 11. The salinity was minimum during July 2010and maximum in May 2010. There was no significant difference observed between the water quality parameters of the twostations (p>0.05). However, difference in salinity was significant between the two culture periods in Station 1 (p<0.05). Nosignificant difference was observed in the nutrient levels of the cage and reference sites and also between the two crops. Nosignificant difference was observed between the mean weight of the fish and temperature of both the sites and periods.A positive correlation was observed between the weight gain of fish and salinity of water at cage site.

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Observations on variations in physico-chemical water parameters ofmarine fish cage farm off Karwar

Cage farming of marine finfish is an alternative to meet increasing demand for food fish. Culture of Asian seabass in open sea floating net cages made of either HDPE or GI pipes, has been successfully demonstrated off Karwar, south India. Fish were fed with chopped oilsardine. Various growth parameters like average daily growth rate (ADGR), survival rate (SR), specific growth rate (SGR) and biomass index (BI) were estimated. Mean weight and length at the end of the 150 days experimental period was 1.02 kg and 412.05 mm respectively with a SR of 68.8%. The economics of cage farming was also worked out. The need to standardise stocking densities and feeding rate has been emphasised.

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S R Krupesha Sharma

Papers

Chronic stress due to high stocking density in open sea cage farming induces variation in biochemical and immunological functions in Asian seabass (Lates calcarifer, Bloch)

Evaluation of immune response and resistance to diseases in tiger shrimp, Penaeus monodon fed with biofilm of Vibrio alginolyticus

First report of isolation and characterization of Photobacterium damselae subsp. damselae from cage‐farmed cobia (Rachycentron canadum)

Observations on variations in physico-chemical water parameters ofmarine fish cage farm off Karwar

Culture of Asian seabass (Lates calcarifer, Bloch) in open sea floating net cages off Karwar, south India