Title: Habitat rehabilitation for inland fisheries: Global review of effectiveness and guidance for rehabilitation of freshwater ecosystems.
Authors: Roni, P., Hanson, K., Beechie, T., Pess, G., Pollock, M., & Bartley, D.M.
Journal: NA
Year: 2005
DOI: NA
Species or groups: Aquatic vegetation, fish (razorback sucker), riparian vegetation, birds
Other sources of evidence: https://www.conservationevidence.com/actions/1741
Abstract: The degradation of inland aquatic habitats through decades of human activities has lead
to massive efforts to rehabilitate freshwater habitats for fisheries and aquatic resources
in watersheds throughout the world. Many texts have been written on techniques
for rehabilitation though no comprehensive worldwide review of the effectiveness of
techniques has been undertaken. This paper reviews published evaluations of freshwater
habitat rehabilitation projects, including studies on roads improvements and sediment
reduction, riparian and floodplain rehabilitation, placement of habitat structures in lakes
and streams, addition of nutrients to increase aquatic production and other less common
techniques. In particular, the authors summarize what is known about the effects of
various techniques for restoring natural processes, improving habitat, and increasing
fish and biotic production. Recommendations on limitations of techniques, which
techniques are effective, as well as information on planning, prioritizing and monitoring
rehabilitation projects are also provided.
Despite locating more than 330 studies on effectiveness, as well as hundreds of
other papers on rehabilitation, it was difficult to draw firm conclusions about many
specific techniques because of the limited information provided on physical habitat,
biota and costs, as well as the short duration and scope of most published evaluations.
However, techniques such as reconnection of isolated habitats, rehabilitation of
floodplains and placement of instream structures have proven effective for improving
habitat and increasing local fish abundance under many circumstances. Techniques that
restore processes, such as riparian rehabilitation, sediment reduction methods (road
improvements), dam removal and restoration of floods, also show promise but may take
years or decades before a change in fish or other biota is evident. Other techniques such
as bank protection, beaver removal and bank debrushing can produce positive effects
for some species but more often produce negative impacts on biota or disrupt natural
processes.
Comparing the cost-effectiveness of different types of rehabilitation techniques
was not possible because few evaluations reported various costs or economic benefits;
however, estimates of average costs for various techniques are provided. Monitoring
and evaluations clearly need to be designed as part of the rehabilitation action. The
authors discuss the key steps to consider when designing monitoring and evaluation of
rehabilitation actions at various scales.
Similar to less-comprehensive reviews of rehabilitation, this review demonstrates
three key areas lacking in most rehabilitation projects: 1) adequate assessment of historic
conditions, impaired ecosystem processes and factors limiting biotic production; 2)
understanding upstream or watershed-scale factors that may influence effectiveness
of reach or localized rehabilitation; and 3) well-designed and -funded monitoring and
evaluation. These are the same factors that consistently limit the ability of published
studies to determine the success of a given technique at improving habitat conditions
or fisheries resources. Finally, this review suggests that many habitat rehabilitation
techniques show promise, but most have not received adequate planning, monitoring or
cost-benefit analysis.
Assessment of reliability and robustness (CEESAT)
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