2009 Salmon Tracking

2009 Report

To read the full report please click here

The River Dee was granted a licence in 2008 to extend its rod and line fishing season from 30 September to 15 October for a trial period of three years, from 2008-2010.  This extension period operates under the Dee Conservation Code which requires that all caught salmon and sea trout be returned. This is a report of the second year of the three year monitoring programme to assess the potential impact of angling in October on Dee salmon stocks.

After a pilot monitoring study in 2008, full monitoring of the season extension in the Lower Dee (downstream of Banchory) was undertaken in 2009. The four methods used to assess impact of the fishery extension on the salmon population were: rod catch analysis; scale sampling; radio tracking of individual salmon; and redd count surveys.

993 salmon (grilse and Multi Sea Winter (MSW) salmon) were caught in the October 2009 fishing extension period (14% of 2009 rod catch), as well as 66 sea trout. 98.7% of October-caught salmon were released (this return rate was 1% higher than for the rest of the season). Fresh, silver salmon comprised a significantly greater component of the Lower Dee fishery (Banchory bridge – Aberdeen harbour) than the Middle Dee fishery (Aboyne Bridge – Banchory Bridge) in October. There was also a small but significant increase in the proportion of coloured, stale fish in the Middle Dee rod catch between the last two weeks in September and the first two weeks of October. There was no such change in the Lower Dee rod catch between these two periods.

Scale samples showed that MSW salmon dominated the October rod catch in the Lower Dee (72% in 2009), with the remainder of the rod catch being grilse. Approximately three quarters of the Autumn rod catch in the Lower Dee comprised Summer and Autumn runs of fish, with the remaining quarter being Spring salmon. There was no evidence that the proportions of these stock components varied between the last two weeks in September and the first two weeks of October.

60 fish that were caught by anglers in the Lower Dee were radio tagged. Tracking of these fish found no significant difference between the movements of fish that were captured, tagged and released in the last two weeks in September compared to fish caught, tagged and released in the first two weeks of October; 66% of the tagged fish migrated further upstream, 21% showed little directional migration (less than 2 miles up- or down-stream) and 13% migrated downstream. The distribution of fish that were captured and tagged in September and October did not differ significantly; the majority (56%) remained in the Lower Dee for spawning, but 30% entered the Middle Dee (above Banchory) and 14% entered the Upper Dee (above Aboyne Bridge). On average, the tagged fish reached their final (spawning) destinations in the second week of November.

Redd count surveys highlighted that spawning occurs earlier in the Western catchment. At sites in the Upper River (Dinnet and further west), spawning started the fourth week of October. In the Middle and Lower Dee, spawning started early-mid November, and there was limited evidence that spawning was earlier in the tributaries in these areas. Spawning was recorded until the end of December in the Lower River (and may have occurred later, but river conditions prevented further surveys being undertaken).

There was no evidence that, in the Lower Dee, capture and handling of salmon in the October extension period had any significant impact on fish survival or ability to migrate for spawning, compared to the capture of fish in the last two weeks of September. There was no evidence that Spring salmon caught in the Lower Dee fishery were negatively impacted compared to other stock components. Therefore the overall conclusion is that the October fishing extension is sustainable in the Lower Dee (downstream of Banchory).

The third year of the season extension monitoring will be undertaken in Autumn/Winter 2010, with a focus on the Middle Dee (between Aboyne Bridge and Banchory Bridge). The final decision on whether to apply for a permanent extension to the fishing season will be made in early 2011, once all data has been reviewed.

 

To read the full report please click here

 

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