International Journal of Aquaculture and Fishery Sciences eertechz (original) (raw)
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Compositional variation of Sundarban Fishes
Climate change in the lower Gangetic delta has caused an increase in water temperature and altered the salinity and pH of the aquatic phase. Such changes have caused a significant alteration in the diversity spectrum of fin fishes prevailing in the system. The Shannon Weiner species diversity indices computed from the catch of commercially important fin fishes and trash fin fishes (sample size = mean of 20 catches of 100 kg each from each landing station; duration 1984 – 2014) indicate a pronounced temporal variation both in the western and central sector of Indian Sundarbans that have contrasting geo-physico-chemical features.
Fish diversity and conservation aspects in an aquatic ecosystem in Indian sundarban
International Journal of Zoology Studies, 2019
Sundarban is the largest delta on the planet.it covers about one million hector. Sundarban situated in the delta of the river Ganga, Brahmaputra and Meghna and it is famous for his marine and estuarine fish resources. Sundarban shared two country borders-one is India and other is Bangladesh.in sundarban around 440 species of fishes, 20 species of prawn and 44 species of crabs are present. But now a days sundarbans faces lots of difficult problems which have an impact on the biodiversity, sustainability and live hood of fish resources and also natural climate changes such as cyclonic storms, low pressure in bay of Bengal, shrinking tiger pawn population, fish seed collection etc. the present study highlight the present status of fish biodiversity in sundarban and their actual threats.
The present study has shown that studied Hooghly river sector supported 87 fish species belonging to 12 orders, 39 families and 69 genera. The order Perciformes was dominant with 8 families and 25 number of fish species followed by the order Siluriformes with 8 families and 24 number of fish species. Fish diversity was assessed by calculating the various diversity indices such as Shannon-Wiener index (H /), Simpson's dominance index (C) and evenness index (J). Higher H / value (3.694) observed in post monsoon and lowest (2.398) in monsoon. High evenness value (0.6930) was recorded during monsoon period. Seasonal water quality parameters such as water temperature (o C), pH, DO, nitrate and phosphates has been recorded and were found suitable for fish population.
Fish diversity studies of two rivers of the northeastern Godavari basin, India
Fish diversity was explored in two rivers of the northeastern Godavari basin: the Adan, tributary of the Painganga, and the Kathani, tributary of the Wainganga. Both rivers are part of the same basin but present different ecological, climatic and anthropogenic settings. Six sites were sampled in each river system over three years using gill nets, cast nets and locally available nets; the ‘catch per unit effort’ criterion was used for sampling. Forty-seven species of fish were identified. Species richness (Jackknife 1 and rarefaction) and diversity measures (Shannon and Simpson) were calculated and their values clearly show that the Kathani is a more diverse ecosystem in terms of fish diversity than the Adan. This difference is mainly due to anthropogenic influences upon the Adan.
Assessment of Fish diversity of Tunga River, Karnataka, India
In the present study, an effort has been made to investigate the fish resources quantitatively by studying the ichthyofaunal biodiversity of Tunga River stretch from Gajanoor fishing village to Kudali of Shivamogga district. Monthly sampling was conducted at three centres during July 2010-June 2012 by using gill nets. A total of 45491 kg fishes from three landing centres were collected and Gondichatnalli recorded maximum followed by Shivamogga and Honnapura. The most abundant fish species was Calta catla (28%) followed by Labeo rohita (17%) and Clarias gariepinus (11%). During present investigation a total of 37 species belonging to 11 families and 4 orders were recorded. The order Cypriniformes found to be dominant with 23 fish species followed by Siluriformes 11 species and Perciformes 2 species. Although, 37 species were recorded, the family Cyprinidae recorded 19 fish species (51.35%) followed by Bagridae, 4 fish species (10.81%) and Claridae with 3 fish species (8.10%) each. The Simpson's index of diversity (1-Lambda') was highest in Gondichatnalli (0.8802) followed by Shivamogga (0.8580) and Honnapura (0.8523). This indicated the greater fish biodiversity in Gondichatnalli when compared to other two centres. The biomass of fish species was more in Gondichatnalli (S= 36, N=19014) followed by Shivamogga (S =31, N= 14671), and Honnapura (S =37, N= 11806). Further, the other indices such as Pielou's evenness (J'), Shannon H'(loge) and Simpson 1-Lambda' were also used to assess the richness of biodiversity of all the three fish landing centres. In this study an attempt has been made to evaluate the ichthyofaunal diversity in the region and suggests mitigating measures.
Salinity based fish composition
Climate change in the lower Gangetic delta has caused an increase in water temperature and altered the salinity and pH of the aquatic phase. Such changes have caused a significant alteration in the diversity spectrum of fin fishes prevailing in the system. The Shannon Weiner species diversity indices computed from the catch of commercially important fin fishes and trash fin fishes (sample size = mean of 20 catches of 100 kg each from each landing station; duration 1984 – 2014) indicate a pronounced temporal variation both in the western and central sector of Indian Sundarbans that have contrasting geo-physico-chemical features.
The current global fisheries production is *160 million tonnes. The quantum is gradually rising as a result of increases in aquaculture production. A number of climate-related threats to capture both the fisheries and aquaculture are identified, but we have high uncertainty in predictions of the future fisheries production because of uncertainty over the future global aquatic net primary production and the transfer of this production through the food chain to human consumption. Recent changes in the distribution and productivity of a number of fish species can be ascribed with high confidence to regional climate variability, such as the El Niño-Southern Oscillation. The future production may increase in some high-latitude regions because of warming and decreased ice cover, but the dynamics in low-latitude regions are governed by different processes, and production may decline as a result of reduced vertical mixing of the water column and, hence, reduced recycling of nutrients. There are strong interactions between the effects of fishing and the effects of climate because fishing reduces the age, size and geographic diversity of populations and the biodiversity of marine ecosystems, making both more sensitive to additional stresses such as climate change-induced salinity oscillation. The estuaries in the lower Gangetic delta at the apex of Bay of Bengal are noted for contrasting spatial variation of salinity. The Hooghly estuary in the western sector is relatively low saline compared to the Matla estuary in the central sector on account of receiving the fresh water discharge from the Farakka barrage. The central sector is hyper saline due to siltation of the Bidyadhari River since the late fifteenth century. The present study evaluates the condition factor of fourteen commercially important fin fish species (that constitute *75 % of the fishes in the catch basket) collected from the Hooghly and Matla estuaries in the western and central sectors of the lower Gangetic delta, respectively. Relatively 347 higher values of condition factor of all the species collected from the Hooghly estuary (compared to those collected from the Matla estuary) confirm the adverse effect of hyper salinity on the growth and condition factor of the species.
2018
Fishes are the most diversified group among vertebrates, with ca. 33,600 species [3] characterized by their great diversity in morphology, physiology, ecology, life history and behavior. Almost 25% of the global vertebrate diversity accounted by fish is concentrated in the 0.01% of the earth’s water. This tiny fraction of earth’s water supports at least 100000 species out of approximately 1.8 million and almost 6% of all are described species [4]. It is often claimed that freshwater ecosystems arethe most endangered ecosystems in the world [5]. This particular vulnerability of freshwater to fish at global scale reflects the fact that both fishand freshwater are the need of humans and consequently they have been heavily impacted by theiruse and regulation. Asia supports over half of the global human population, with enormous consequent pressures on inland waters and freshwater fish biodiversity [4]. The freshwaters in India are one of the most exploited resources since past many year...