The degraded state of the fragile ecosystem of Chilika lagoon on the east coast of India caused by natural changes and anthropogenic pressure was in the process of restoration through an effective hydrological intervention during 2000 after thorough scientific investigation including EIA study. The rich fisheries of Chilika lagoon that support livelihood of 0.2 million local fisherfolk was in dwindling state during the ecodegradation phase. Studies on fisheries and fish biodiversity of the lagoon for 4 years before and 4 years after the intervention showed the stark and rapid recovery of fishery immediately after opening of the new mouth with sixfold increase in average annual landing. The average productivity (11.3 t km -2 ) and CPUE (6.2 kg boat-day -1 ) during post intervention phase registered 528 and 464% increase, as compared to Pre-intervention years. In total, 277 species of fish and shell fish were documented as occurring in Chilika lagoon before the hydrological intervention. Inventory survey for fish and shell fish species diversity during and after hydrological intervention documented 68 and 97 species, respectively. New records of 56 species of fish and shell fish (7 freshwater, 20 brackishwater and 29 marine) were documented from Chilika lagoon after the hydrological intervention. Analysis of commercial catches showed that the migratory species contributed to the bulk of catches (75% by species and 68% by catch weight). Fish yield and biodiversity seemed to be very sensitive to salinity and hydrologic dynamics of the lagoon. Correlation analysis indicated inverse relationship between water transparency and fish catch (R 2 = 0.715; d.f. = 25; P < 0.01). Positive correlation between salinity and prawn landing (R 2 = 0.542; d.f. = 25; P < 0.01) and salinity and mud crab landing (R 2 = 0.628; d.f. = 25; P < 0.001). Average salinity for the whole lagoon was significantly increased by 42.7% (P < 0.007) as compared to pre-intervention situation. Maintenance of estuarine character of Chilika's ecosystem particularly the salinity gradient, un-hindered auto-recruitment of fish and shell fish and prevention of destructive fishing are the key factors for fisheries enhancement. Unless carefully planned conservation and regulation measures are ensured with the active participation of local communities during the early phase of restoration, the present scenario of fisheries enhancement may not sustain for longer time.

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Chilika Lake, an assemblage of marine, brackish and freshwater ecosystems, on the east coast of India is a designated Ramsar site and a biodiversity hotspot. Intensive ichthyofaunal inventories and biodiversity assessments were carried out during 2000–2014 and documented 317 species belonging to 207 genera, in 88 families and 23 orders, including two endemic (Gobiidae) and one exotic cichlid species (Oreochromis mossambicus). In total, 255 collections (178 collections of previously recorded species and 77 that represent newly recorded species) were made during a post-restoration survey accounting for 80.44% retrieval of historically documented species. This paper presents an updated and comprehensive checklist of the lake’s ichthyofauna (1916–2014), which is comprised of 278 food fishes, 271 (85.49%) migratory and 46 (14.51%) are resident species indicating that the lake fishery is largely migratory species-dependent. An account of faunal characteristics for 129 commercially important species is provided. The checklist also documents 48 threatened species and 103 species under different categories of conservation status.

The growth, mortality and stock status of grey mullets Chelon parsia (Ham. 1822), Chelon planiceps (Val. 1836) and Mugil cephalus (Linn. 1758) were investigated during December 2010 to November 2011 from Chilika Lake, Asia, largest brackish water lake. The length‐based analysis, using length frequency data collected from fish landing centres, formed the basic study methodology. Growth function and population parameters were studied using FAO‐ICLARM Stock Assessment Tools‐II (FiSAT‐II). The von Bertalanffy growth function (VBGF) was established as Lt = 321 mm*(1 − exp (‐0.98 year−1 × (t + 0.085 year)) for C. parsia, Lt = 315 mm × (1 − exp (−0.80 year−1 × (t + 0.105 year)) for C. planiceps and Lt = 700 mm*(1 − exp (−0.70 year−1*(t + 0.097 year)) for M. cephalus. Lower K and higher L∞ values for M. cephalus indicated slow growth and high longevity of the species, compared to other grey mullets. Length–weight relationships were derived, indicating isometric growth for grey mullets. Recruitment of mullets was observed throughout the year, with a peak during April–July. About 50% of the mullets were caught by fishing gear before reaching their first year of age. The level of exploitation (E ≥ 0.60) was more than the optimum level (E = 0.4 for pelagic stock), indicating overexploitation of grey mullets in Chilika Lake. Moreover, the average annual yields of three mullets were observed to be higher than the estimated maximum sustainable yields (MSY), also indicating overharvesting of mullets. Thus, the mullets could be considered one of the highly overexploited resources in Chilika Lake. The findings of this study will facilitate the development of appropriate management strategies for the mullet fishery in Chilika Lake.

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The degraded state of the fragile ecosystem of Chilika Lake, located on the east coast of India, was undergoing restoration through an effective hydrological intervention during the year 2000. Studies on the lake's hydrobiology and fisheries for the period of 7 years before and 7 years after the hydrological intervention indicated a rapid recovery of the lake fishery immediately after opening of the new lake mouth, with a sixfold increase in the average annual fish landings. During the average fisheries output (11 051.3 t), catch per unit effort (6.2 kg boat )1 day )1 ), the economic valuation of the average annual catch (637 million rupees) and productivity (11.97 t km )2 ) exhibited dramatic increases of 498%, 464%, 1177% and 498.5%, respectively, compared with the 7-year pre-intervention data. Multivariate statistical analysis inferred that most of the lake's environmental variables are strongly associated with salinity factor, which seems to have governed the lake ecology. The salinity dynamics of the lake are governed by both freshwater inflows and seawater ingress through the new artificial lake mouth. Correlation analysis indicated that salinity was positively correlated with prawn catch (R 2 = 0.542; d.f. = 25; P < 0.01), crab catch (R 2 = 0.628; d.f. = 25; P < 0.001) and fish catch (R 2 = 0.476; d.f. = 25, P < 0.05). The average increase in the salinity regime (43.8%) for the lake during the post-hydrological intervention period, compared with the pre-hydrological intervention period, appears to have positively impacted the fish, prawn and mud crab catches. A gradual decrease in total fisheries output since 2005-2006, however, was attributed mainly to a continuing increase in destructive fishing practices in the absence of any conservation and regulatory measures for fishing, and large-scale collection of shrimp juveniles from the outer channel for shrimp aquaculture. Thus, carefully planned conservation and regulation measures must be ensured, with active participation of local communities during this early phase of lake restoration. In the absence of such measures, the present scenario of fisheries enhancement might not be sustained over the long term.

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