The survey was conducted from March 2012 to March 2013 based on field observations and samples. Shesher is natural reservoir of Lake Tana found at coordinates of 0350300 and 1322162 UTM and at altitudes 1805 a.s.l. Welala natural reservoir is found at UTM coordinates of 0348348 and 1326081 with altitude of 1804 a.s.l. The area of Shesher and Welala was estimated about 500 ha and 110 ha respectively, which are impounded by open water for extended period of a year and both with maximum depth of 3 m during rainy season. Both reservoirs filled their capacity during the rainy season through the inflow river of Ribb and the surrounding flood plain. But during pick dry season of March, 2012 and March 2013 the survey showed unexpected, amazing and sudden death of a home for many biodiversity that both Shesher and Welala natural reservoirs dried up totally. Birds fetch their food from remnants small shrink wet mud spot and it is not uncommon to see remnant dead fishes eaten by birds. This is due to several and unlimited human encroachments mainly for crop cultivation, with out any rules and regulations. Major crops cultivated by drained two reservoirs using gravitational force were Eragrastis teff, Cheak pea, Grass pea, Lentils and Safflower. During dry season no one could be able found drinking water even for their animals and humans, inhabitants started digging well to fetch water from the middle of Shesher and Welala reservoirs. The drainage system was carried out at every 50 m intervals by making large furrows in both sides of two reservoirs until their water totally vanished. These reservoirs should be properly and sustainably exploited by designing appropriate interventions with out land use change, for instance it could be serve for fisheries, ecotourism and livestock sectors.

Climate change poses new challenges to the sustainability of fisheries and aquaculture systems, with serious implications for the 520 million people who depend on them for their livelihoods and then early 3 billion people for whom fish is an important source of animal protein [1]. Two-thirds of all reefs are in developing countries, and 500 million people in the tropics depend heavily on reefs for food, livelihoods, protection from natural disasters and other basic needs. For many coastal communities in reef areas, fishing activities are the sole source of income. Climate changes may affect fisheries and aquaculture directly by influencing fish stocks and the global supply of fish for consumption, or indirectly by influencing fish prices or the cost of goods and services required by fishers and fish farmers. Potential loss of species or shift in composition for capture fisheries and impacts on seed availability for aquaculture, changes in precipitation and water availability are major impacts of climate change. Climate change lowers water quality causing more disease and increased competition with other water users which altered and reduced freshwater supplies with greater risk of drought. Fishing communities that depend on inland fisheries resources are likely to be particularly vulnerable to climate change. Higher inland water temperatures may reduce the availability of wild fish stocks by harming water quality, worsening dry season mortality, bringing new predators and pathogens, and changing the abundance of food available to fishery species.

The status of Lake Tana Fishery was evaluated from analysis of commercial catch data of number I fishers cooperative. The data collection has been carried out from September 2003 to September 2009. Results indicated that Nile tilapia (Oreochromis niloticus), African catfish (Clarias gariepinus) and species flock of endemic, large Labeobarbus spp. were the three main species groups targeted by commercial gillnet fishery of Lake Tana and form 65 %, 20 % and 15 % of the annual catch compositions of fish species during the study period respectively. There was significant variability among sampling years encompassing temporal aspects. Especially, commercial catch of O. niloticus were significantly booming up to 2007 and declining after wards. The most likely explanations for the declining catch of O. niloticus and others are the illegal use of undersized monofilament gillnet imported from Sudan town (Gelabat) and the harmful increase of the commercial gillnet fishery targeting the spawning aggregations of L. barbus spp. and C. gariepinus in the river mouths and littoral areas. The observed decline in the commercial catch of O. niloticus and others stress the need for the urgent development of a management plan focusing on controlling import of undersized monofilament gillnet, fishing effort and gear restrictions in the river mouths and major tributaries during the breeding seasons and implementing the regional fishery legislation.

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 aquatic phase of the western Indian Sundarbans exhibited a gradual rise of commercially important fin fish diversity, while in the central sector the diversity of the trash fish variety increased over a period of more than two decades. The trash fin fish variety here indicates low priced fishes that are mostly used for poultry and fish feed preparation after sun drying.

Dmc1, a member of the RecA/Rad51 super family, is essential for meiotic recombination. In this study, a Dmc1 gene (EsDmc1) was identified from screening the larval transcriptomes of Chinese mitten crab Eriocheir sinensis. The full-length cDNA of EsDmc1 was 1478 bp long and contained a 1026 bp open-reading frame encoding 341 amino acids. The genomic fragment of EsDmc1 contained two exons separated by one intron. Several tandem repeats were found in intron. The deduced EsDmc1 protein contained motifs conserved in the RacA/Rad51 superfamily, including the Walker A and B motifs, and L1 and L2 loops. EsDmcl shared 87.3%, 86.5% and 77.4% identity with its homologues in Litopenaeus vannamei, Penaeus monodon and Ixodes scapularis, respectively. Phylogenetic analysis revealed that EsDmc1 had a closer relationship with Dmc1s from arthropods than vertebrates. The EsDmcl transcripts could be detected in all examined larval stages with the highest expression level in the fifth zoeal stage. These results suggest that EsDmc1 could be expressed before reproductive maturity and might have complex functions in crab reproduction.