Variation in fish catches from the continental shelf between Quilon and Gulf of Mannar and its relation to oceanographic conditions during the southwest monsoon period

The present paper is based on the fishing results of FORV Sagar Sampada during July-August, 1987 along the southwest coast of India. The fish fauna of the Quilon Bank and Wadge Bank has a dominant nemipterid element and the Gulf of Mannar area has a dominant population of barracudas. Nemipterids constituted 88.2 and 64.4% of the total trawl catch from the Quilon Bank and Wadge Bank respectively

Aquaculture

Not AvailableWhite feces syndrome (WFS) has recently been reported as a serious problem for shrimp aquaculture in major shrimp farming nations. WFS affected shrimp show white/golden brown intestine, reduced feed intake, stunted growth and is often associated with loose shell, while WFS affected pond show masses of floating white feces on the surface of the pond. Accumulation of aggregated transformed microvilli (ATM) structures in hepatopancreas (HP) lumen that superficially resemble gregarine are reported to cause WFS. But the causal association of ATM and WFS is unknown. Also, WFS occurrences are significantly associated with incidences of the emerging microsporidian Enterocytozoon hepatopenaei (EHP) in the Penaeus vannamei grow-out system. The present study unveiled the occurrences of EHP spores along with ATM structures in the WFS affected shrimps. The histology section stained with calcofluor white stain (CFW) and semithin section revealed the presence of EHP spores in and around the transformed microvilli. Further, EHP spores were detected in all the individual WFS affected shrimps and white fecal threads by light microscopy and SWP-PCR. All WFS samples tested negative for WSSV, IHHNV, IMNV, and AHPND. None of the Vibrio isolates were found predominant in WFS affected shrimps. In bioassay studies, by feeding with WFS affected HP tissue, white fecal threads were successfully reproduced along with ATM structures and EHP spores. However, purified EHP spores (106 ml?1) failed to elicit WFS in challenged animals. In the clinical experiment, when WFS affected shrimp were reared under optimal laboratory settings, white feces were found to resolve, and the animals excreted normal feces in about 7?10 days, without any interventions. Further, histological studies showed the epithelial cells (E cells or embryonic cells) regeneration ability in WFS resolved shrimp. However, the WFS recovery observed was not a complete recovery since the resolved shrimps continue to shed EHP spores in normal feces. It is observed that EHP is the major pathogen excreted/disseminated via white feces in shrimp. With this study, we postulate that WFS is a clinical condition/shrimp diarrhea associated with severe EHP infection that may be caused by EHP in combination with an unknown agent

Journal of Invertebrate Pathology (Journal of Insect Pathology)

Not AvailableHepatopancreatic microsporidiosis (HPM) is an infectious shrimp disease caused by the microsporidian Enterocytozoon hepatopenaei (EHP). In recent years, the widespread occurrence of EHP poses a significant challenge to the shrimp aquaculture industry. Early, rapid and accurate diagnosis of EHP infection is very much essential for the control of HPM crop-related losses. Loop-mediated isothermal amplification (LAMP) is a robust, sensitive, cost-effective disease diagnostic technique. Here, we demonstrate an improved, simple, closed-tube, colorimetric EHP LAMP diagnostic assay. LAMP assay was illustrated with the specific EHP spore wall protein (SWP) gene primers. Naked eye visual detection of LAMP amplicons was achieved using Hydroxy naphthol blue (HNB) or Phenol red dye without opening the tubes. This LAMP assay is efficient in detecting the EHP pathogen in all clinical samples include shrimp hepatopancreas, FTA card samples, feces, pond water, and soil. Also, the elution of EHP DNA from FTA cards was demonstrated within 17 min using a simple dry bath. In clinical evaluation, the visual LAMP assay established 100% diagnostic sensitivity and 100% diagnostic specificity. The visual LAMP assay is rapid, can detect the EHP pathogen within 40 min using a simple dry bath, and does not require any expensive instruments and technical proficiency. In conclusion, this visual LAMP protocol is a user-friendly, specific assay that can be conceivably operated at the farm-site/ resource-limited settings by the farmer himself with simple equipment

Not Available

Not AvailableThe use of chemicals, biologicals and veterinary medicinal products (VMPs) helps in healthy and sustainable fish production. Information on the use of these products is essential for assessing farming practices, potential human health and environmental risks. A questionnaire-based nationwide survey covering aquaculture farms (n = 2936) producing carps, tilapia, pangasius and rainbow trout in freshwater and shrimp in brackishwater estimated the use of 52 different types of inputs which included disinfectants (597 g t−1), probiotics (2.28 kg t−1), environmental modifiers (22.82 kg t−1), nutritional supplements (1.96 kg t−1), natural anti-infective agents (293 g t−1), herbicide and piscicides (844 g t−1), antibiotics (2 mg PCU−1), antifungal (4 mg PCU−1), and antiparasitic (14 mg PCU−1) agents. The bulk of these inputs was used for soil and water quality improvement and had low environmental and human safety concerns. The multivariate analysis revealed significant variation in the frequency and quantity of compounds use among farm groups. Redundancy analysis revealed a significant association between the number of products used and stocking density. The survey also showed a considerable influence of education and farming experience on the usage pattern of aquaculture inputs. Results of the study indicated greater reliance of farmers on the use of disinfectants for biosecurity, nutritional supplements for enhanced growth and environmental modifiers for maintaining soil and water quality in culture systems. Though there was no use of restricted antibiotics and antiparasitic agents, the development and implementation of standard regulatory guidelines are essential for safe and effective use of inputs for sustainable aquaculture.Indian Council of Agriculture Researc