Fish

The fish module is used to assess the status of wadeable streams on the basis of fish.

Fish are good indicators for assessing the condition of streams because they show the interaction of various human influences on the streams over longer periods of time. These include changes in structural habitat diversity, flow regulation, the presence of migration barriers and chemical water quality.

What is assessed:

Quantitative electrofishing is used to survey the fish population in a section of the stream. An assessment is then made as to whether the fish community is near-natural and site-appropriate and whether the diversity and abundance of fish corresponds to that of only slightly polluted streams. From these results, conclusions can be drawn about the condition of the stream and the fish ecology.

Recorded parameters:

Species spectrum and dominance ratios, fish densities and biomasses, population structure of sensitive species, deformations or anomalies (not included in the assessment).

Evaluation:

The assessment is carried out by comparing the observed fish population with the fish population to be expected under near-natural conditions.

The electronic FishAssess tool is available for evaluating the data collected.

The assessment is carried out in five status classes.