SMALL STREAMS: Contribution to populations of trout and sea trout.
Report of a workshop held at Carlingford, Co. Louth, Ireland on 27 and 28 November 2012 |
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The Small Streams Risk Score (SSRS) System
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- 20/ It was noted that the Flylife Partnership’s Anglers Monitoring Initiative used very similar methods in Great Britain. It is not known to what extent similar systems existed in other Member States, most of which lack good historical records of invertebrate species and abundance.
- 21/ In discussion it was noted that it was important to that ensure macroinvertebrate taxa were sampled in both winter and summer; sampling in early summer, for example, before emergence, could produce artificially low figures, and some sources of pollution, such as septic tanks, had a greater impact in summer, with populations recovering over winter. Results needed to be mapped and recorded, with records easily accessible. Continuous, long term records were particularly valuable. These could identify changes to taxa and to a stream’s productivity, although caution was needed in interpreting results in view of natural variability.
Mapping Small Streams
22/ Biological records need to be linked to accurate geographic information. Wetted area, either directly measured or derived from channel length, upstream catchment area and Shreve river index, is currently used to define the extent of fish habitat in a catchment. It was noted, however, that modern GIS technology provided a powerful tool, and made it possible to record and display a wide range of additional habitat data. Moreover, the land through which a stream flowed, in terms of geology, vegetation and farming practices, had a major influence on in-stream habitats. Multi-layered GIS based maps could also be used to display the ecosystems services that could be delivered by small streams. It was noted that the Sea Trout Workshop had recommended the development of a GIS based inventory of sea trout rivers[2], and this was being taken forward via the Celtic Sea Trout Project. The workshop recommended that this should be extended to cover small streams in order to quantify their contribution to catchments and display location in relation to potential pressures.
22/ Biological records need to be linked to accurate geographic information. Wetted area, either directly measured or derived from channel length, upstream catchment area and Shreve river index, is currently used to define the extent of fish habitat in a catchment. It was noted, however, that modern GIS technology provided a powerful tool, and made it possible to record and display a wide range of additional habitat data. Moreover, the land through which a stream flowed, in terms of geology, vegetation and farming practices, had a major influence on in-stream habitats. Multi-layered GIS based maps could also be used to display the ecosystems services that could be delivered by small streams. It was noted that the Sea Trout Workshop had recommended the development of a GIS based inventory of sea trout rivers[2], and this was being taken forward via the Celtic Sea Trout Project. The workshop recommended that this should be extended to cover small streams in order to quantify their contribution to catchments and display location in relation to potential pressures.