Fishing gears diversity in Sunamganj, Haor region within CBRMP's working area

This book is a research output on fishing gears used in the beels from Sunamgan Haor areas under the initiative of the Community Based Resource Management Project (CBRMP) of LGED and WorldFish. It presents a collection of gears recorded in the CBRMP project area during monitoring conducted by WorldFish from 2008 to 2012. The book contains a total of 63 gears found in Sunamganj haor area.

Introduction to fish species diversity: Sunamganj haor region within CBRMP's working area

This book is a modest attempt at identifying Sunamganj haor fish species, especially in areas falling under the Sunamganj Community Based Resource Management Project (CBRMP). It contains a total of 126 fish species from 39 families found in the Sunamganj haor area. CBRMP has promoted community based fisheries management approaches that, along with their livelihoods focus, are helping to preserve and enhance natural fish stocks in the hoar basin. WorldFish support to LGED involves a number of areas including monitoring the impacts of CBRMP on fish catch, bio-diversity and livelihoods.

Severe droughts reduce estuarine primary productivity with cascading effects on higher trophic levels

Using a 10-yr time-series data set, we analyzed the effects of two severe droughts on water-quality and ecosystem processes in a temperate, eutrophic estuary (Neuse River Estuary, North Carolina). During the droughts, dissolved inorganic nitrogen concentrations were on average 46–68% lower than the long-term mean due to reduced riverine input. Phytoplankton productivity and biomass were slightly below average for most of the estuary during a spring–autumn drought in 2002, but were dramatically lower than average throughout the estuary during an autumn–winter drought in 2007–2008. Droughts affected upper trophic levels through alteration of both habitat condition (i.e., bottom-water dissolved oxygen levels) and food availability. Bottomwater dissolved oxygen levels were near or slightly above average during the 2002 drought and during summer 2007. Concomitant with these modest improvements in bottom-water oxygen condition, fish kills were greatly reduced relative to the long-term average. Low-oxygen bottom-water conditions were more pronounced during summer 2008 in the latter stages of the 2007–2008 drought, and mesozooplankton abundances were eight-fold lower in summer 2008 than during nondrought years. Below-average mesozooplankton abundances persisted for well over 1 yr beyond cessation of the drought. Significant fish kills were observed in summer 2008 and 2009, perhaps due to the synergistic effects of hypoxia and reduced food availability. These results indicate that droughts can exert both ephemeral and prolonged multiyear influence on estuarine ecosystem processes and provide a glimpse into the future, when many regions of the world are predicted to face increased drought frequency and severity due to climate change.

Nocturnal fish movement and trophic flow across habitat boundaries in a coral reef ecosystem (SW Puerto Rico)

Few studies have quantified the extent of nocturnal cross-habitat movements for fish, or the influence of habitat adjacencies on nutrient flows and trophodynamics. To investigate the patterns of nocturnal cross-boundary movements of fish and quantify trophic connectivity, fish were sampled at night with gillnets set along the boundaries between dominant habitat types (coral reef/seagrass and mangrove/seagrass) in southwestern Puerto Rico. Fish movement across adjacent boundary patches were equivalent at both coral reefs and mangroves. Prey biomass transfer was greater from seagrass to coral reefs (0.016 kg/km) and from mangroves to seagrass (0.006 kg/km) but not statistically significant, indicating a balance of flow between adjacent habitats. Pelagic species (jacks, sharks, rays) accounted for 37% of prey biomass transport at coral reef/seagrass and 46% at mangrove/seagrass while grunts and snappers accounted for 7% and 15%, respectively. This study indicated that coral reefs and mangroves serve as a feeding area for a wide range of multi-habitat fish species. Crabs were the most frequent prey item in fish leaving coral reefs while molluscs were observed slightly more frequently than crabs in fish entering coral reefs. For most prey types, biomass exported from mangroves was greater than biomass imported. The information on direction of fish movement together with analysis of prey data provided strong evidence of ecological linkages between distinct adjacent habitat types and highlighted the need for greater inclusion of a mosaic of multiple habitats when attempting to understand ecosystem function including the spatial transfer of energy across the seascape.

Seasonal variation and species diversity of fishes in the Neyyar River of the Western Ghats

Temporal variation in the abundance of fish populations and diversity of assemblages in different sections of the Neyyar River in the Western Ghats were investigated during the year 1984. A decreasing trend in the abundance of fishes from the headwaters downwards has been noted. The fish community is represented by 33 species assignable to 15 families. The diversity indices of Shannon-Wiener and Margalef and Pielou's evenness have been calculated. The diversity indices are discussed in the light of species richness in different sectors.

Diversity of wetland fish and its impact on the income of fishermen community of Assam.

A survey was conducted in 3000 fishermen households surrounding 54 wetlands (Beels) of Assam. The fish diversity of the wetlands has been decreasing during the last few years due to some extrinsic and intrinsic factors. The total number of fish species recorded so far during the present study is 67 belonging to 21 families. Cyprinidae is the most dominant family represented by major group species (8), intermediate group species (3) and minor group species (12) of high commercial value. Among these three groups, the diversity of fish species is higher in the minor group fish. The present paper deals with the economic condition of the fishermen who mainly fish in the wetlands. The economic condition of the fishermen community is found very poor. The income of fishermen varies from Rs. 4.478 to Rs.7,484 per annum. A regression analysis shows that the income of fishermen is not dependent alone on the fish production but it is exclusively dependent on the value of the fish catch. All the three groups (in terms of value) have significant influence at 10.00% confidence level. But analysis of β shows that the intermediate fish group exhibits the highest influence on the variation of the fishermen income followed by minor and major group respectively.