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Radio tracking of the Ribble’s Spring Salmon, 2013 (Year 2) By Gareth Jones. In Review
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By Gareth Jones
Each springer’s behaviour has been unique in terms of the distance swam. Fish movement patterns are typically well-defined in those swimming shorter distances. This means that some fish are able to conserve energy more readily in seeking out suitable habitat and are better prepared for the stressful months ahead.
The timing of each migration correlates with increased river heights. In 2013, fish migrations also occurred later into the winter than in 2012 and were more frequent throughout the year. Seasonally, the tagged springers have spent the late spring searching for suitable lies during the summer months. Typically, they will occupy deep pools and/or well-oxygenated parts of the main stem Ribble. Here, they will remain until the floods of October/November raise the river levels encouraging them toto seek mates upon suitable spawning riffles. Generally, these are located between Clitheroe and Long Preston.
A lack of spawning activity in the Ribble’s tributaries was observed in 2013 when low summer levels were maintained. Our annual electrofishing survey programme demonstrated that young fry and parr were present here, a positive sign that they are providing nursery areas for Ribble springers.
Motivation and methods
In response to the diminishing spring run of salmon on the Ribble, a three year investigation into their migratory pathway was initiated by the Ribble Rivers Trust, the Environment Agency and the Ribble Fisheries Consultative Association. The main objective has been to locate where the Ribble springers head to spawn. Understanding these whereabouts would enable targeted river habitat improvement works in the hope of boosting this increasingly rare creature’s futureprospects.
The year’s first arrival of a springer could not be accurately predicted nor established from results from the project’s first year due to time constraints. From the start of February 2013 trapping recommenced using the previous years methods. These entail using afish-trap that adjoins an existing weir and provides the most likely means of its circumnavigation. Once captured the salmon are anaesthetised, measured and a radio transmitter attached. The tagged fish are released by one of our angler volunteers and all work is carried out under the supervision of EA Fishery Officers. By working closely with our local angling clubs we have elected to not tag all captured salmon and attempted to avoid those most recently captured and released or exhibiting signs of external damage. All of our methods have been scrutinised by the relevant authorities and are conducted under Home Office best practice guidelines. The project team have continue to make improvements towards reducing handling times, data capture and efficiency.
In our second year we extended the trapping period from the 1st February until the 16th June (compared to the 12th April until the 15th May the previous year). The increased effort was not rewarded with fewer captures made. Eighteen, as opposed to twenty-six springers were radio tagged during this period. Five of these fish were tracked through to spawning in November/December amongst the high river levels. Of the eighteen fish tagged the largest in size weighed 24.5lbs, with the average capture weighing 14lbs. All fish were highly silvered with two having freshly attached liced fish. All but one of the fish arrived during a single flood and were predominantly male (10 of the 18).
Results from 2013
Of the eighteen tagged salmon, five were tracked through to spawning which occurred in mid November. All five locations mapped to areas of the main river above Clitheroe and superimposed with last year given one exception (see schematic in the panel below). In 2013 no springers were observed as spawning in tributaries and efforts were partially impacted by the high water levels. In contrast, three fish spawned on Skirden, Stock and Long Preston becks the previous year.
The one ‘exception’ was observed amongst other late spawners successfully cutting redds within a main stem riffle near Long Preston. Within a fortnight, a small (tagged) hen fish swam up through Settle towards the foss at Stainforth. Here, it is anticipated that the fish has spawned at the foot of Stainforth Beck. Owing to a lack of main river spawning gravels locally the options for spawning salmon are restricted. This occurrence represents the most upstream location of any springer tagged during the project to date.
One tagged springer was caught in June in the Clitheroe area. This was kept with the angler notifying us and returning the tag to us for re-use.
Four and five tags were confirmed as regurgitations and mortalities respectively. The fates of the remaining four tags remain unknown i.e. the outcome was either a regurgitation or a mortality and the tag has yet to be recovered.
(Above left) A eutrophied Ribble during low summer flows, 20th July 2013 exemplifying the stressful conditions for springers.
(Above right) Evidence of habitat improvement work being undertaken following the results from the first two years work.
Back in April, 2013 local dive club ‘Reefers and Wreckers’ of Barrow, nr Whalley volunteered to assist the project with recapturing radio tags. Half of the tags used in the first year were rediscovered. With another dive planned for 2014 and more tags recovered there will be enough for the project to continue in 2014 without necessitating any further expense.
With trapping recommencing back on 1st February the final year of the project is well underway with the first fish captured on the 8th March, earlier than the previous two years. We hope that this is positive early sign conducive towards a successful spawning year for 2014.
For detailed catchment –wide fisheries reports please visit http://www.ribbletrust.org.uk/news/reports/ or visit our salmon blog at http://www.ribbletrust.org.uk/projects/salmon-tagging/
Chart (above) Migration distances travelled by four tagged spring salmon throughout of the course of this (red coloured lines) and last years programmes (green).
Schematic representation of the River Ribble in relation to Waddow Weir, Clitheroe. The whereabouts of the ten main lies (upper diagram) and five spawning locations (lower diagram) upon the main stem Ribble, 2013. A more comprehensive overview of the project will be provided at the end of this year’s work.
Sponsored fishes ‘Helen’ (above, left) and ‘Maloney’ (above, right) weighed in at 16lbs and 11.5lbs and were captured in mid-May, 2013. Maloney remained ahead of the other tagged fish for the summer period sat in the Long Preston Deeps area and dropped back down river 5 miles in order to spawn amongst the later running salmon. In 2013 a sponsorship scheme was launched through the RFCA to generate funds towards the project. Thanks is offered to all those who have contributed in the second year of the project.
The caudal peduncle of the sponsored fish ‘Helen’ covered with lice having swam swiftly upriver during May.