Damming a river may bring electric power, but it often comes at the price of high-quality food fisheries, experts say. When dams are proposed for power, flood control or irrigation, the often devastating impacts on fisheries in rivers and lakes are ignored or discounted.

This report by the UN Environment Programme (UNEP) and the World Fish Centre warns that despite over 40 years of steady production globally, rapid environmental changes are occurring which challenge the viability of future fish stocks and a range of internationally- agreed development targets including the Millennium Development Goals.

The report is available online at http://www.unep.org/pdf/Blue_Harvest.pdf

This report prepared by the Bureau of Reclamation and the US Fish and Wildlife Service in December 2008 analyzes the Central Valley Project Improvement Act (CVPIA) and its impacts on increasing the populations of anadromous fish in Central Valley rivers and streams. The CVPIA (1992) had a goal of doubling the population by 2002, which didn't happen. The report claims that this goal will not be achieved unless renewed commitments and improvements are made to the program.

A independent science panel review concludes that the California's Central Valley Project Improvement Act's salmon doubling program has failed to achieve its goal for the number of reasons. The panel also makes a number of recommendations.

We evaluated the impact of land cover on fish assemblages by examining relationships between stream hydrology, physicochemistry, and instream habitat and their association with fish responses in streams draining 18 watersheds of the Lower Piedmont of western Georgia. Several important relationships between land use and physicochemical, hydrological, and habitat parameters were observed, particularly higher frequency of spate flows, water temperatures, and lower dissolved oxygen (DO) with percentage impervious surface (IS) cover, higher habitat quality with percentage forest cover, and elevated suspended solid concentrations with percentage pasture cover. Fish assemblages were largely explained by physicochemical and hydrological rather than habitat variables. Specifically, fish species diversity, richness, and biotic integrity were lower in streams that received high frequency of spate flows. Also, overall fish assemblage structure as determined by nonmetric multidimensional scaling was best described by total dissolved solids (TDS) and DO, with high TDS and low DO streams containing sunfish-based assemblages and low TDS and high DO streams containing minnow-based assemblages. Our results suggest that altered hydrological and physicochemical conditions, induced largely by IS, may be a strong determinant of fish assemblage structure in these lowland streams and allow for a more mechanistic understanding of how land use ultimately affects these systems.

This paper presents the results of an ex post survey of recreational anglers for the lower Kennebec River, post-Edwards Dam removal. To the best of our knowledge, this study represents one of the first ex post analyses of fisheries restoration from dam removal. We find significant benefits have accrued to anglers using the restored fishery. Specifically, anglers are spending more to visit the fishery, a direct indication of the increased value anglers place on the improved fishery. Anglers are also willing to pay for increased angling opportunities on the river. These findings have policy implications for other privately owned dams that are currently undergoing relicensing and ⁄ or dam removal considerations. Our findings may also hold implications for fisheries that have deteriorated due to historic dam construction.

Most recent instream flow studies used one of three approaches. (1) PHABSIM remains popular but has major flaws, including the failure to establish and appropriate spatial resolution and use it throughout the method: a decision variable, Weighted Usable Area, that lacks biological meaning; and lack of a sound conceptual basis, which encourages ad hoc and poorly conceived methods for applying the approach. Some of PHABSIM

historical review and archeologic investigation into the abundance of Atlantic Salmon in pre-colonial/prehistoric New England. Prehistoric archeological record indicates virtual absence of atlantic salmon in the region. In order to investigate a climatically induced hypothesis for salmon appearance and disappearance, environmental an dclimatic factors affecting range shifts and the mechanisms of migration in salmon were studied. Atlnatic salmon are likely to be verey recent colonizers to North America, particlarly to New England. Today's fish an dwildlife managers appear to have largely ignored the paleoenvironmental databases that present long-term records of climatic change in concert with animal and plant species range changes, and even total extinctions

This essay highlights the necessity for the establishment of new instream flow standards, as well as the revision of existing standards. This presents a problem since the standards themselves cannot be defined scientifically. The authors recommend the implementation of an adaptive management program involving three elements; setting conservative interim standards; establishment of an adequate monitoring program involving active manipulation flows; and establishment of effective procedure to revise the interim standards. The program details should vary from case to case, especially for species like salmon, where adult populations depend on a myriad of factors, not simply instream flows. Examples of current and previous uses of these standards are given.