Fish Physical Habitat Research Articles

Evaluating Attraction and Passage Efficiencies of Pool-Weir Type Fishways Based on Hydraulic Analysis

In this study, a hydraulic analysis technique is presented for evaluating the efficiency of a pool-weir type fishway. The River-2D model with the fish physical habitat module was used for the analysis of the attraction efficiency, and the weighted usable area proposed as an index of the efficiency. For the analysis of passage efficiency, the three-dimensional model, FLOW-3D, was used as an evaluating tool to describe the fluid behavior on a hydraulic structure with a free surface. The ice-harbor type fishway at Dalseong weir in the Nakdong River of Korea was selected as a test-site, and the efficiency was estimated using the hydraulic analysis. The results of River-2D analysis showed that the location of the fishway near the right bank now was not appropriate for attracting the target fish to the fishway due to the deep water depth. The 3D analysis results presented that the flow velocity field inside the fishway showed a similar plunging flow in each pool, but various flow patterns appeared locally.

Assessment of aquatic habitat effect by artificial change of streambed topography

As interest in ecosystems and the environment has recently increased, efforts for the preservation and restoration of river ecosystems have increased. The purpose of this study is to estimate the fish physical habitat by artificial change of streambed topography applying two-dimensional simulation model, River2D. A total reach length of 130 m along the Je stream located within the Geum River basin in Korea was used in this study. The target fish is the dominant fish species, Zacco platypus, which was evaluated for two growth steps (adult and spawning). Five scenarios were considered which included the installation of small dams at three different heights (0.25 m, 0.50 m, and 1.00 m) and installation of small pool with 0.25 m and 0.50 m depth. Results indicated that for natural streambed conditions the adult optimum flow was 1 m(3)/s, and the spawning optimum flow was 3 m(3)/s. The mean annual outflow for the natural condition was 0.64 m(3)/s, lower than the evaluated optimum flows. Applying the three discharges observed in 2008 to the five scenarios, the installation of the small dam increased the weighted usable area (WUA) while the installation of pools decreased the WUA, both as compared to the WUA for the natural condition.

Freshwater Fish Habitat: Science, Management, and Conservation in France

Abstract Characteristics of French water bodies and fish fauna are described with special reference to physically altered streams. Recent researches on fish physical habitat have produced new insights on: models of probability of fish distributions at a watershed scale, fish ecology, in particular about their habitat preferences, hydraulic statistical modelling with simplification of data collection, models of impacts of flow or modifications to stream morphology, and coupling physics and biology. These models have been validated at fish population (trout) or assemblage (Rhône river) level. Other complementary researches are dealing with fluvial dynamics necessary to maintain habitat or with ecological dynamic linked to flows and morphology (especially substrate). For the legal point of view, Fishing law (1984 in FCE a), Water law (1992 in FCE b), and the last European Water Framework Directive (2000) defined the limits of hydrosystems utilization. They defended the principle of an equilibrium between hydrosystems utilization. It is also necessary to better link streams and their watersheds. Waterbodies regionalization will be a good way to reduce the natural variability of physical and biological situations in order to better manage ecological entities with respect of their sensitivity. The setting of a national survey of fish communities is fundamental. National conservation programmes with main protected areas of France has not been very successful at protecting freshwater fish. Rehabilitation plans of some emblematic fish species Salmon, Sturgeon, Eel, Shad have helped to coordinate actions in large heavily anthropised rivers. In other numerous aquatic systems, it is better to restore the functioning of the first key compartments, hydrology and morphology. Fish communities are in these cases good measures of the benefits of rehabilitation actions. Future research will deal with different interfaces between physics and biology, in order to better manage channels, sediments, flows, and riparian vegetation.