Assessment of the impact of fish seed stocking on fish yield in small reservoirs of Central India: towards sustainable management.

The present study investigates the success of stocking fingerlings of Indian major carps ‐Gibelion catla (Hamilton), Labeo rohita Hamilton and Cirrhinus mrigala Hamilton – to enhance fish yield in 58 small reservoirs in Odisha State, India. Fish stocking and yield data were collected from State Fisheries Department, Odisha. The relationships between area, stocking density and fish yield of different size groups of reservoirs were assessed using the Pearson correlation coefficient (r). Fish yield increased significantly (p < 0.05, t‐test) from 204 kg/ha/year in 2012–13 to 323 kg/ha/year in 2013–14 due to adoption of CBF. The corresponding per capita fish production increased from 398 kg fisher−1 year−1 to 702 kg fisher−1 year−1 benefitting more than 8,000 fisher households. Reservoirs in the size group 100–500 ha showed the highest response of fish yield with respect to stocking of fingerlings. The size of fingerlings at stocking and area of the reservoir had greater impact on enhancing fish yield. Stocking had a profound positive impact on fish yield. This study forms a baseline evaluation of the impact of stocking on small tropical reservoirs in India. It also recommends management measures and discusses issues, and the way forward for sustainable fisheries enhancement in small tropical reservoirs in eastern India.

The relationships between surface area, stocking density and fish yield in 40 small reservoirs in India between 1994 and 1999 were examined. A significant positive correlation (r = 0.6) was found between stocking density and fish yield. Area was negatively correlated with stocking density (r = −0.57) and fish yield (r = −0.62), but its correlation with efficiency of stocking was not significant for all the size groups of small reservoirs.

A field experiment was conducted during wet season to evaluate the performance of different fish species for biocontrol of weeds in rainfed waterlogged rice fields with fingerlings of three exotic carps – grass carp, Ctenopharyngodon idella (Val.) (Cyprinidae, Cypriniformes), silver barb, Puntius gonionotus (Bleeker) (Cyprinidae, Cypriniformes) and common carp, Cyprinus carpio (L.) (Cyprinidae, Cypriniformes) – and three Indian major carps – rohu, Labeo rohita (Ham.) (Cyprinidae, Cypriniformes), catla, Catla catla (Ham.) (Cyprinidae, Cypriniformes), mrigal, Cirrhinus mrigala (Ham.) (Cyprinidae, Cypriniformes). A total of 13 major weeds under the categories of grassy, sedges, broadleaf and aquatic weeds were observed in the rice fields. Grass carp reduced maximum weed biomass (weed control efficiency [WCE] 63% at 60 days after transplanting [DAT] and 62% at 100 DAT) followed by silver barb and common carp. Among the Indian carps, only rohu was effective in control of weeds (WCE, 23% at 60 DAT). The grain yield of rice (variety Varshadhan) slightly increased (4.2–4.5 t/ha), but straw yield was significantly higher (10.2–10.7 t/ha) under rice-fish farming. Fish yield was significantly higher in exotic carps (270–288 kg/ha/90days) due to higher specific growth rates (1.8–2% body weight/day). The study indicated that exotic carps (grass carp, silver barb and common carp in order) were more effective than Indian carps for control of weed in rainfed lowland rice fields and among the Indian carps, rohu showed potential for weed control.

An experiment on polyculture of mahseer with Indian major carps at same stocking density was carried out for a period of 10 months from February 1 to December 1, 2004 in six experimental ponds. There were three treatments with two replicates each. Treatment 1 was designed with catla (Catla catla), rohu (Labeo rohita) and mrigal (Cirrhinus mrigala), treatment 2 with catla (Catla catla), rohu (Labeo rohita) and mahseer (Tor putitora) while treatment 3 with catla (Catla catla), rohu (Labeo rohita), mrigal (Cirrhinus mrigala) and mahseer (Tor putitora). Mahseer of the treatment 2 was introduced instead of mrigal of treatment 1 and 50% of mrigal was replaced with mahseer in treatment 3. The stocking density in all the treatments was 30 fish/decimal (7500 fish/ha). The feeds were supplied at the rate of 3-7% of the body weight of fish. The gross and net productions recorded were 5362.78 and 5188.64, 5431.42 and 5262.32, 5357.11 and 5528.74 kg/ha/yr in treatments 1, 2 and 3 respectively. Though there was no significant difference (p>0.05) among the three treatments using ANOVA but the production in treatment-3 was slightly higher than treatments 1 and treatment 2. However, there was no negative effect of mahseer on the growth and production of Indian major carps. So, it can be concluded that polyculture of mahseer with Indian major carps (catla, rohu and mrigal) can be done in ponds.DOI: http://dx.doi.org/10.3329/pa.v18i2.18194 Progress. Agric. 18(2): 175 - 182, 2007

An year long experimental multi-species farming of Indian major carps (IMC) and minor carps was conducted with varied stocking densities in 15 earthen ponds (0.08 ha) to develop a suitable farming model. The IMC group included Catla catla, Labeo rohita and Cirrhinus mrigala at 35:40:25 ratio while minor carp and barb (MCB) group included Puntius gonionotus , Labeo fimbriatus and Puntius sarana at 40:35:25 ratio. Fingerlings were stocked in five density combinations (treatments) as: T1 - IMC at 8000 ha-1, T2 - IMC at 8000 ha-1 + MCB at 4000 ha-1, T3 - IMC at 4000 ha-1 + MCB at 4000 ha-1, T4 - IMC at 4000 ha-1 + MCB at 8000 ha-1 and T5 - MCB at 16000 ha-1. Survival of all species in both groups showed inverse relation with their stocked densities. T4 with IMC and MCB at 4,000 and 8,000 fingerlings ha-1, respectively, formed the ideal density with 28.8 and 76.0% higher yield realisation compared to T1 with only IMC and T5 with only MCB group, respectively. All multispecies treatments having MCB group as major component yielded higher fish biomass than those with IMC group. Such results indicated potential of multispecies farming system to increase production in seasonal ponds and water bodies retaining lower water level.

An year long experimental multi-species farming of Indian major carps (IMC) and minor carps was conducted with varied stocking densities in 15 earthen ponds (0.08 ha) to develop a suitable farming model. The IMC group included Catla catla, Labeo rohita and Cirrhinus mrigala at 35:40:25 ratio while minor carp and barb (MCB) group included Puntius gonionotus, Labeo fimbriatus and Puntius sarana at 40:35:25 ratio. Fingerlings were stocked in five density combinations (treatments) as: T1 - IMC at 8000 ha-1, T2 - IMC at 8000 ha-1 + MCB at 4000 ha-1, T3 - IMC at 4000 ha-1 + MCB at 4000 ha-1, T4 - IMC at 4000 ha-1 + MCB at 8000 ha-1 and T5 - MCB at 16000 ha-1. Survival of all species in both groups showed inverse relation with their stocked densities. T4 with IMC and MCB at 4,000 and 8,000 fingerlings ha-1, respectively, formed the ideal density with 28.8 and 76.0% higher yield realisation compared to T1 with only IMC and T5 with only MCB group, respectively. All multispecies treatments having MCB group as major component yielded higher fish biomass than those with IMC group. Such results indicated potential of multispecies farming system to increase production in seasonal ponds and water bodies retaining lower water level.

The present study evaluated the effectiveness of stocking the Gangetic carps, viz. Labeo catla, Labeo rohita, and Cirrhinus mrigala, in a large tropical reservoir, Uttar Pradesh, India. Time series data of 22 years (1998 to 2019) on fingerling stocking and fish harvest were collected from the State Department of Fisheries, Govt of Uttar Pradesh. The average annual stocking was 36 nos.ha−1 yr−1, and the fingerling stocking size was ranged between 10 and 90 mm total length (TL) with a mean of 30 mm TL. The average fish production potential of the reservoir was estimated at 77.15 kg ha−1 yr−1. The analysis revealed that fish yield from the reservoir progressively increased from 75.02 t to 297.39 t with a mean of 148.82 ± 69.45 t. The regression analysis between the stocking density and yield of stocked species showed an insignificant relation in the reservoir (R2 = 0.0873, p = 0.2495). The percentage change in the production of stocked species in comparison with the previous year was found to be negative for 12 years between 1998 and 2019 indicated an unstable trend. The finding indicated that low stocking density, very small size at stocking, the low conversion efficiency of the photosynthetic energy to fish (0.016%), and the dominance of catfishes were the major causes for the low fish productivity. We suggest greater stocking density of 500 fingerlings ha−1 yr−1, stocking of fingerlings (> 100 mm TL), in situ breeding and rearing in cages and pens, adoption of cage culture technology, and identification and conservation of the breeding ground of the Gangetic carps to optimize the management regime in utilizing the production potential of reservoirs vis-a-vis ensuring livelihood security and sustainability of the fishers.

Pahuj, a small reservoir, located at Jhansi in Uttar Pradesh was investigated during April 2006 to March 2009 for evaluating fish yield potential. The reservoir receives a portion of Jhansi city sewage through Pahuj River. As per the physico-chemical parameters, the reservoir has been categorized as eutrophic. Average fish yield during 1994-95 to 2008-09 was 142.03 kg ha-1year-1, whereas during study period (2006-07 to 2008-09) it was 286.43 kg ha-1year-1. The potential fish yield was estimated using morpho-edaphic index, which revealed that the reservoir have potential to produce up to 560.78 kg ha-1year-1. Thus, there is scope for enhancing the fish yield in the reservoir if proper management measures are adopted. Key words: Small reservoir, eutrophication, production potential, fish yield

Fingerlings of common carp (Cyprinus carpio), Thai silver carp or tawes (Puntius gonionotus), Nile tilapia (Oreochromis niloticus) and mrigal (Cirrhinus mrigala) were stocked in rainfed lowland riceflelds in Northeast Thailand in 1986 and 1987. In both years, farmers harvested on average 50 kg•ha·1 of stocked fish species. Farmed fish yields were corelated with stocking densities. Feeding practices did not contribute to fish yields. Average recovery rates in both years were about 16%, but recovery of tawes was much better than of the other species. Nursery-paddies to increase recovery rates were not successful. The fingerling costs exceeded the market value of the fanned fish with 40% of the farmers. The average wild fish yield over both years was 209 kg 0ha·1, mostly snakehead (Channa striata) and catfish (Clarias batrachus and C. macrocephalus), with some climbing perch (Anabas testudineus ). Wild fish yields in both years were corelated with water depths in the field. The market value of the wild fish equalled the market value of the rice crop. Wild fish caught by household members from ricefields were the most important source of animal produce consumed during the rice-growing season (68%).

The present study deals with stakeholder-driven implementation of pen culture for raising of fish seed for Culture-based fisheries (CBF) in Chamta, a floodplain wetland, in Gangetic plains through polyculture of Indian Major Carps (IMCs) Labeo catla, Labeo rohita and Cirrhinus mrigala with Small Indigenous Fishes (SIFs) Labeo bata, Systomus sarana and grass carp, Ctenopharyngodon idella in co-management mode. In the first polyculture trial IMCs and minor carps were cultured in 4 High Density Poly Ethylene (HDPE) pens (0.1 ha each) at a stocking density of 25 Nos. m−3 in equal numbers for 90 days. In the second polyculture trial IMCs were cultured with grass carp at a density of 25 Nos. m−3 in 4 HDPE pens in the ratio of 1:1:1:2 for 90 days. The same set of pens was utilized for both trials during different times of the year. Net yield of 682.3 ± 20.6 kg and 413.9 ± 21.7 kg per pen was achieved through polyculture of IMCs and SIFs and polyculture and for IMCs and grass carp, respectively. The survival percentage varied with species and culture period with overall survival of 77 (IMCs + minor carps) to 85% (IMCs + grass carp). Polyculture was economically feasible with a BC ratio of 2.01 for IMC and SIFs and 1.88 for IMC and grass carp. All the seeds produced in the pens were released to the wetland as input for CBF. The study indicated the potential of grass carp fishery in macrophyte-infested wetland. The species could attain 1.5–2 kg in 6 months and up to 3–3.5 kg weight within 1 year, utilizing macrophyte resources of the wetland. SIFs S. sarana and L. bata were observed to attain maturity in pens. The study indicated pen as an economically feasible technology to boost CBF in the wetland. The cultivation of SIFs through pen culture and CBF can enhance their production while alleviating pressure on their natural populations. Integrating pen culture using diversified species will promote sustainable fisheries management in these floodplain wetlands.

This study investigated whether allochthonous inputs generated by cattle and water buffaloes grazing in the catchment or wading in the water in small village reservoirs of Sri Lanka can make a significant effect on yields from culture-based fisheries of those reservoirs. The analysis is based on limnological data of 37 randomly selected reservoirs. As culture-based fish yield data were available over the 2002 - 2003 period only for 23 reservoirs, fish yield data from seven more reservoirs were gleaned for the present analysis. Cattle and water buffalo densities (BD) in 37 reservoirs where limnological data were available, were found to be significantly correlated to the biological productivity-related parameters such as chlorophyll-a content. Culture-based fish yield in the 30 reservoirs varied from 54.6 to 1800.8 kg ha-1 and BD associated with the reservoirs studied varied from 0.90 number ha-1 to 216.25 numbers ha-1. Fish yield (FY) was significantly correlated with BD the relationship being, FY = 4.758 BD + 242.740 (R2 = 0.345; p<0.001). The importance of taking into consideration factors such as grazing cattle and buffalo density in preparing management strategies for culture-based fisheries in small village reservoirs is discussed.

The present project was planned to study gradual replacement of Cirrhinus mrigala with Cyprinus carpio and its impact on pond ecosystem. A total of 900 fishes belonging to six species viz. Catla catla, Labeo rohita, Cirrhinus mrigala, Ctenopharyngodon idella, Hypophythylmichthys molitrix and Cyprinus carpio were stocked in four earthen ponds. The dimensions of each pond were 220 × 198 × 7 feet length, breadth and depth. The stocking density in pond 1 (T1) was C. catla 150, L. rohita 200, C. mrigala 200, C. idella 150, H. molitrix 150 and C. carpio 50. The stocking density of C. mrigala and C. carpio in pond 2 (T2) was 150 and 100, in pond 3 (T3), 100 and 150 and in pond 4 (T4) it was 50 and 200, respectively while the stocking density of all the other four fish species remained constant in all the four ponds. All the fish were fed with a diet of 25.16% crude protein at 2% body weight. C. idella and C. mrigala showed maximum growth in T1, C. catla and H. molitrix in T2, L. rohita and C. carpio in T3. Maximum growth was observed in T3 followed by T4, T1 and T2. Among fish species C. idella and C. carpio showed higher growth rates than the rest of fish species. Our results reveal that in polyculture system stocking density of C. mrigala and C. carpio in a ratio of 1: 1.5 gives better results. Key words: Aquaculture, freshwater, phytoplankton, zooplankton, exotic fish.

Tropical reservoir ecosystems cover more than 3.51 million ha in India which are the major sources of fish production from inland open waters and supports rich diversity of fish. The present study quantifies fisheries enhancement and evaluates the impact of stocking of Indian major carp fingerlings in six large reservoir ecosystems of India. Analysis of time series data revealed a significant increase (p < 0.05) in fish yield from 12.3 kg ha−1 year−1 in 2004–2005 to 52.4 kg ha−1 year−1 in 2016–2017 due to stocking. The average fish yield of these six reservoirs was estimated to be higher than the national average of 33 kg ha−1 year−1 recorded for large Indian reservoirs. Fingerling stocking had a significant positive impact on fish yield (r = 0.238, p = 0.035). The reservoir water storage level was positively correlated (r = 0.621, p < 0.05) to fish production. The study also shows that the reservoir habitat support 99 finfish species in the central Indian reservoirs of which two species belong to endangered category warranting conservation efforts. This study is the first of its kind on assessing the impact of stocking in large number of tropical reservoirs including the largest reservoir in the country revealing positive effect on fish yield. The fish yield of 85.8 kg ha−1 year−1 obtained in Gandhisagar reservoir (72,300 ha), India revealed that fisheries enhancement is effective and remunerative. The study also highlights the global status of stocking impact in large reservoirs and deliberates issues and suggests management strategies for sustainable fisheries enhancement in large tropical reservoirs.

Increased temperature, decreased water level and reduced culture period of the ponds are considered major problems for aquaculture promotion in drought prone Barind area of Bangladesh. In order to address these problems, an experiment was conducted to optimize the stocking weight for carp polyculture ponds in Tanore Upazila of Rajshahi district. Three different stocking weights were tested under three treatments (T1: 25±0.12 g; T2: 50±0.15 g; T3: 100±0.19 g), each with three replications. Fish growing period (July–December), carp species (Catla catla, Hypopthalmichthys molitrix, Aristichthis nobilis, Labeo rohita and Cirrhinus mrigala), stocking density (7,410 individuals/ha), lime and ash treatment, fertilization and feeding were same for all the treatments. Water quality (water temperature, dissolved oxygen, transparency, pH and alkalinity) and fish growth parameters were monitored monthly. Mean values of water quality parameters were found within the suitable range for fish culture. Treatment T3 varied significantly (P<0.05) than that of other treatments for the mean values of final weight, weight gain, specific growth rate, survival rate and yield of fish. Net benefit of carp polyculture was also found the highest in treatment T3. Use of higher stocking weight can be a suitable option for carp polyculture in ponds under drought prone Barind area.

The harvest of microalgae from the effluent of a sewage fed high rate stabilization pond by Tilapia nilotica