Indian Council of Agricultural Research
CENTRAL MARINE FISHERIES RESEARCH INSTITUTE

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Fish Community Structure and Trophic Status - A Measure of Ecological Degradation

Powai lake, a monomictic shallow lake, presenting some characteristics typical of a progressive trophic state specifically the permanent turbid water, the recurrent occurrence of cyanobacterial blooms which occasionally leads to large fish kills and the reduction in biodiversity. The study was carried out to understand the ecological degradation of Powai lake by using the abiotic and biotic factors. Twenty-four fish species were recorded and the fish yield was found to be 98 kg ha yr where -1 -1 here the actual potential lies about 363 kg ha-1 yr-1. The diet composition of 10 of the most abundant fishes in the lake revealed that, there were about 13 major food items from the gut contents, includes phytoplankton green algae, phytoplankton blue-green algae, diatoms, cladocerans, copepods, benthic algae, benthic weeds, macrophytes, detritus, fish eggs and larvae, shrimps, fish scales and insects parts. The Food Richness index (N) varied from 12 (Heteropneustes fossilis) to 29 (Oreochromis mossambicus), Diet Breadth (D) from 0.12 (Heteropneustes fossilis) to 0.77 (Oreochromis mossambicus) and the Gut repletion index (GRI) as 100% for all the species. Most of the fish species in the lake were either planktivores or detritivores with high feeding avidity and trophic adaptability, hence are capable of altering diet according to availability. The estimated trophic level indicates that almost all the fishes in the lake depend on primary producers or consumers as their diet. The dominance of omnivores and planktivores and the submissive occurrence of carnivores in the lake indicates the rampant ecological degradation of the lake.

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Assessment of marine debris in the stake net fisheries of Vembanad Lake, Kerala, India

The stake net fishery of Panambukad in the main channel area of Vemband Lake, Kerala was studied during the first fortnight of August 2014. The observations indicated that the average catch including the marine debris ranged from 1.04 to 2.04 kg net-1 day-1 with an average of 1.34 kg net-1 day-1. The percentage of marine debris in the stake nets ranged from 42.68 to 73.4%. Plastic items formed 97% by weight and 99% by number of the total marine litter. The observed litter stuff was categorized as per UNEP system of classification of marine litter where, they are first identified based on their material composition (litter codeeg. PL) and then by their form (RL classes). Items found in the collection included plastic covers (PL07, RL15), metal cap (ME02, RL01), plastic bottle (PL02, RL02), fishing net (PL20, RL05), plastic cup and food containers (PL06, RL09), thermocol (FP 04, RL13), rubber sheet (RB05, RL28), plastic sacks (PL24, RL23), diaper (OT02, RL18) etc. Among them, plastic covers were most dominant and their average number and weight net-1 day-1 was 28 nos and 985 g respectively. The study also showed positive signs of decline in plastic bottles as a major litter item due to its targeted collection by recycling industry within a span of three years. In a survey conducted among the stake net fishers, there was consensus on the view that plastic litter in Vembanad Lake has increased during the last 10 years and this has affected the resources and the fishery. The stakeholders also expressed their willingness to pay for restoration of the fishery resources of the lake. The study recommends the need to establish proper solid waste management systems in coastal villages, to reduce the use of plastics, and provide facilities for disposal of litter which gets collected in stake nets and to increase the awareness among the public about the impacts of marine debris on ecosystem and resources.

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Overfishing and Climate Drives Changes in Biology and Recruitment of the Indian Oil Sardine

The recent fluctuations in abundance of the Indian oil sardine Sardinella longiceps, a tropical small pelagic clupeid fish, was investigated in the light of overfishing and variations in its habitat ecology in southeastern Arabian Sea. In 2012, its landings peaked to an all-time record making it the fifth largest sardine fishery in the world, and within 3 years the catches were reduced to nearly a tenth of that level. This study examined the fishery dependant factors such as effort, catch rates and expansion of fishing area; the biological variations in fish size, maturity and recruitment; and tried to relate this to the environmental variations in the sardine habitat and food availability. The 2012 mega harvest was a result of a 2-time increase in gear size and engine capacity of fishing crafts and a 3.7-time increase in fishing effort. The female maturation process was strongly influenced primarily by rainfall and then by upwelling and the resulting influx of cold nutrient-rich water in the habitat from April much before the start of the monsoon in June. After 2013, the weak monsoons and the 2015 El Nino Southern Oscillation resulted in a warmer (by an average of 1.1°C) period which negatively impacted the maturation process. The abundance of jellyfishes which are larval and young fish predators in the habitat negatively affected recruitment after 2013. The mismatch in timing of phytoplankton productivity and sardine larvae in the habitat also affected the recruitment success. These environmental divergences coupled with the excessive capture (beyond maximum sustainable yields) of spawning stock and juveniles from 2010 has resulted in this biological catastrophe which has affected the livelihood of thousands of small-scale fishers. A more responsive fisheries administration with timely restriction on fishing effort and protection of spawning stocks by way of fishery closure would have helped minimize the impacts.

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First record of deep-sea caridean shrimp from southwest coast of India

The present work reports the new occurrence of deep-sea shrimp Acanthephyra fimbriata Alcock & Anderson, 1894 from southwestern Indian waters. The samples were caught in bottom trawls conducted between the depths of 200 and 350 m from two fish landing centers off Kerala along Arabian Sea from the southwest coast of India during 2015. Additionally, a phylogenetic analysis was used to explore the relationships of the genus Acanthephyra based on two genes: mitochondrial cytochrome c oxidase subunit 1 (COI) and 16S DNA (16S) with the present specimen and sequences retrieved from NCBI GenBank. The results revealed intraspecies (COI: 0–3 % & 16S: 0–0.3 %) and interspecies divergence (COI: 17.5–20.9 % & 16S: 5.2–9.5 %) among A. fimbriata.

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First report of a lactonic disecosteroid from the buccinid gastropod Babylonia spirata

A lactonic steroid with an unprecedented 1, 10: 8, 9-disecoergostane framework was identified from the ethyl acetate-methanol extract of buccinid gastropod mollusk, Babylonia spirata collected from the southwestern coast of Indian peninsular region. The compound was characterized as 1, 10: 8, 9-disecoergosta-8-en-A-homo-6a-oxa-1-one by exhaustive spectroscopic methods including two-dimensional nuclear magnetic resonance and mass spectroscopic investigations. The disecosteroid displayed moderate carbolytic enzyme inhibition activity as distinguished by its inhibitive effects against ?-amylase and ?-glucosidase (IC50 0.40 and 0.54 mg/mL, respectively). The anti-inflammatory (5-lipoxidase inhibitory) activity of the titled secondary metabolite was found to be superior (IC50 < 0.85 mg/mL) than the commercial anti-inflammatory drug (ibuprofen IC50 > 0.85 mg/mL). However, significantly greater antioxidant property was recorded for the studied disecosteroid as evaluated by in vitro 2, 2-diphenyl-1-picrylhydrazyl radical inhibition potential (IC50 0.30 mg/mL) than that of standard, ?-tocopherol (IC50 > 0.50 mg/mL). The in silico molecular docking studies were conducted to explain the anti-5-lipoxidase and anti-?-amylase properties of the isolated compound. The molecular binding interactions of the ligands with the pro-inflammatory 5-lipoxidase and the carbolytic enzyme ?-amylase, demonstrated that their binding energies/docking scores were positively associated with their in vitro bioactivies. A plausible pathway for the biosynthetic origin of lactonic disecosteroid in B. spirata was proposed from an ergosterol precursor. Structure-activity correlation study demonstrated that the biological activities of the disecosteroid were directly proportional to their electronic properties allied with lesser steric restrictions.

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Recent Nesting Record of Female Green Turtle at Pamban, Gulf of Mannar

A female green turtle was sighted at Pamban along the Gulf of Mannar just after the nesting on the beach on 15th January 2011. Morphometric measurements of the turtle were taken and data suggests that this individual is adult. A total number of laid eggs were 109. The distance between the nesting site and the high tide line was found to be 7 m. The depth and diameter of the nesting pit was 52 and 16 cm, whereas the mean egg diameter and weight were found to be 44.3 mm and 40.5 g respectively. Pamban coast may also be considered an important place for nesting, because of the continuous mixing of waters of GOM and Palk Bay areas, which in turn create current patterns continuously throughout the year in addition to the monsoon season. Conservation of nesting habitat along Gulf of Mannar will be important to maintain the green turtle population.

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