A visit to the (Welsh) river Dee fish trap

by Stephen Greogry - sgregory@gwct.org.uk

Anton Ibbotson and Stephen Gregory of project Morfish recently paid a visit to the Cyfoeth Naturiol Cymru/Natural Resources Wales fish trapping facility on the river Dee in Chester.

Ian Davidson and Rich Cove kindly gave us a guided tour and showed us the fantastic facility in action.

The schematic below shows the trap which is located at the tidal limit. Ian and Rich are currently catching good numbers of both salmon and trout in the Dee.

 



The potential benefits of catching returning spawning fish are obvious to Anton and I. With the fish in your hand you're able to measure length and weight precisely and take biological material such as scales and fin clips.

 

We currently use a passive monitoring system for spawners meaning we detect the returns on either the adult counter or the PIT tag system. By having biological data on the returning spawners we would be able to investigate changes in the condition over time, allowing us to investigate possible drivers of stock sizes over time.

 

One last photo - Anton Ibbotson chasing fish around the trap floor:

 

Working towards a standard salmon stock monitoring programme

The GWCT's Stephen Gregory recently presented a talk on the recommendations for monitoring and modelling of salmon populations based on the shared experiences of scientific researchers working on Project Morfish.

The slides are below. Please contact Stephen on sgregory@gwct.org.uk for more information.

View Towards a standard salmon stock monitoring programme and other presentations by sgregory.

IFM smolt monitoring workshop

The Institute for Fisheries Management (IFM) with the Scottish Fishery Co-ordination Centre (SFCC) held a workshop on smolt monitoring on the 14th May 2014.

Details of the workshop can be found here.

Sadly, no-one from the GWCT Fisheries group or the INRA Ecology and Ecosystem Health unit could attend because we were all involved with our own long-term monitoring programmes.

Nevertheless, we did prepare and send this informative MorFish poster:

Trout Life History Project - An Update

Acoustic tracking of trout smolts

The near shore migration behaviour of post-smolt sea trout potentially impacts their life history choices. Parameters that may be affected by migration choices of post-smolts are growth rate, fecundity and timing of first spawning migration.

Vemco VR2W receiver

Acoustic tags were chosen to study post-smolt migration behaviour in the near shore environment. Unlike radio tags and PIT tags, acoustic tags actively transmit signals that can be heard effectively in the marine environment.

We chose to use V6 tags made by Vemco, the world’s leading manufacture developer of acoustic technology for fish tracking. The V6 tag is 6 mm in diameter, 16 mm long, weighs 1 gr and has a detection range of approximately 200 metres.

On the 26th of March 10 Vemco WR2W receivers were deployed throughout Poole Harbour. The receivers (listening stations) were deployed strategically to record movement both into and out of Poole Harbour as well as potential feeding areas (see Map 1 below for location of the receivers in Poole Harbour).


Map 1: Location of WR2W receivers in Poole Harbour, the area shaded red represents
approximate detection range of the receivers. Click image to enlarge.

In addition to the receivers monitoring movement in the harbour, receivers were deployed in the River Frome at Bindon Mill, East Stoke, and at the tidal limit by the bypass around Wareham (see Map 2 below for position of in-river receivers). These in-river receivers were deployed to monitor post tagging in-river loss rate and freshwater migration speed.

Map 2: Location of East Burton eel rack (yellow dot) and WR2W receivers
in the River Frome (red dots). Click image to enlarge.

Capture and tagging of trout smolts

We acquired 50 V6 tags for the 2014 smolt run and another 50 tags for the 2015 smolt run.



Trapping trout smolts on the Eel Rack at East Burton

Tagging of the trout smolts is done at the eel rack at East Burton, 8 km up-stream of East Stoke. The eel rack at East Burton represents a piece of cultural history as it was made many decades ago to trap down-stream migrating silver eels for commercial purposes.

The eel rack at East Burton has been restored and is now an excellent tool for GWCT to intercept down-stream migrating fish in a fish friendly manner. Click here to see a video clip of an eel rack in operation on the River Test.

The capture and tagging at the eel rack commenced on the 28th of March and was carried out at night time as this is the time when the majority of smolts migrate. The trout smolts were captured, anaesthetised, measured, weighed, scales taken, PIT and acoustic tag inserted, moved to a recovery tank and released when fully recovered (see pictures below for tagging process).

The last of the 2014 tags were deployed on the 23rd of April.

Trout smolt on measure board with acoustic and PIT tags

Insertion of acoustic tag

Trout post-surgery

Tracking of tagged trout smolts

By 21st of Aril 70% of the tagged trout had been recorded entering the tidal section of the river. The battery life of the acoustic tags is 105 days from the day they are deployed. This battery life of the acoustic tags will give us an excellent window into the migration behaviour of the tagged post-smolts in the near shore area.

However, as the battery in the acoustic tags will run out before their first spawning migration we also fitted the smolts with PIT tags. The PIT tags will enable us to record returning adults on our PIT readers at East Stoke and Bindon Mill.

GWCT Fisheries Research

To find out more about the GWCT's fisheries work please click here and to find out more about our trout research please click here.

2013 Salmon research report now available online

Our 2013 salmon research report has been published and is now available to download as a PDF.

The abstract from the report is below:

2013 was the 41st year of the salmon counter’s operation at East Stoke. It was an extremely good year for the juvenile phases of salmon with high numbers of every life stage being recorded. For the adults it was very poor. Parr numbers in the river in September 2012 were very good: the third highest since 2002 and the number of autumn migrant parr that went past East Stoke was high: the second highest we have recorded. The spring monitoring of smolts was excellent and, at over 13,000, was over twice the number recorded in 2012.

On the adult count, equipment failure meant that some data that we normally collect on salmon movement was lost. For this reason we have added an efficiency estimate to the collected data to give an estimated nett upstream count of 343 fish.

This is the lowest number ever recorded on the counter. Adult numbers calculated from PIT tag returns give an estimate very similar to this (383) so we are confident that the numbers were low. This low number of adults is also in agreement with our prediction last year about low numbers of grilse returning this year.

The collaboration with the Poole Harbour netsman continues with only one sea trout caught, tagged and released in 2013.

Our research (with Cefas) on the effect of using rotary screw traps to assess salmon smolt numbers was completed and results will be analysed and written up as soon as possible. The research on the medium and long-term effect of Archimedes screw turbines on salmon smolts and eels also got underway using the facility at Bindon Abbey.

Our current Passive Integrated Transponder (PIT) tag detection equipment is getting very fragile and the manufacturer is no longer supplying new equipment. After reviewing available options we have found sponsorship and funding to replace the readers with new ‘state of the art’ equipment. The new detectors will be better able to withstand the high river flows we have recently experienced and installation should take place this summer.

Mean annual discharge (up to December) was above average, however, the mean monthly discharge in January 2014 was the highest ever recorded for that month.

Finally we are continuing to work with our French colleagues at INRA in Rennes, France, on the Monitoring for Migratory Fish (MorFish) project which will compare data to give us a better understanding of the changes in our populations of migratory fish.

Professor Nick Sotherton
Director of Research, Advisory & Education

Download GWCT 2013 Salmon research report >

Webcam installed at our Salmon & Trout Research Centre

We've recently hooked up with Farson Digital Watercams who have installed a webcam at our Salmon & Trout Research Centre on the River Frome.

As well as watching a live feed from the centre you can also view photos showing recent river heights and conditions.

Go to webcam >

Chalk Streams - an Institute of Fisheries Management talk

The Institute of Fisheries Management has arranged a talk on Chalk Streams by Lawrence Talks, editor of FISH Magazine. The subject is the value and management of chalk streams. This is a rare opportunity to learn a bit more about our fascinating rivers. There are always new things to learn about chalk streams!

It will be in Teffont Village Hall on Thursday 20th March at 7pm. Tickets are £5 and include a glass of wine. All money goes to the charity Afghanaid.

Contact Selaine on 07801 427358 or selainesaxby@hotmail.co.uk to book your place.

The current scene at our Salmon & Trout Research Centre

These photos were taken on 25th February at our Salmon & Trout Research Centre on the Frome at East Stoke in Dorset. They show the high water flow through the counter and flooding:

Electric Fishing Courses in May

We're running courses for people who use electric fishing to catch fish at our Salmon and Trout Research Centre in East Stoke, Dorset.

Taking place on 14th May, the courses cover all the requirements of the Lantra National Occupational Standards section FiM 10 and FiM 12 ‘Catch fish using electro fishing techniques’.

Places are limited to just 20 so be quick if you wish to book your place.

Find out more >

How to PIT-tag a salmon parr

Our state of the art research facilities on the River Frome include electronics that enable us to record the migration history of individual fish. Each September, since 2005, we have fitted 10,000 salmon parr with Passive Integrated Transponder (PIT) tags that transmit an individual barcode when a fish swims past one of our antennae.

Approximately 10% of the Frome salmon population is fitted with PIT tags, helping to make the River Frome salmon population one of the most comprehensively studied in Europe.

This is how we tag the salmon:

1. The parr are caught by electro-fishing. Two teams work on the river for three weeks until 10,000 parr have been tagged. An average of 400 parr are tagged each day per team.

2. The fish is anaesthetised and the length and weight are recorded. Scales are collected and are used to look at growth rate, age and to determine sex.

3. A small insertion is made with a scalpel and a PIT tag is inserted into the body cavity where it will remain for the lifetime of the salmon.

4. The fish is transferred to a holding tank to recover before being released into the 100-metre section where it was caught.

Our salmon work

We're conducting vital research into what is causing the decline in salmon numbers with the ultimate goal of reversing that decline...

Click here to find out more >

Salmonids in the floods

You may have noticed we're experiencing a bit of wet weather at the moment in the UK with flooding heaping misery on people across the country.

Flooding on the River Avon at GWCT HQ in January 2014

Whilst the effects of flooding on humans are all too obvious, we are not the only species to be affected by floods. Fish inhabit the very rivers that are bursting their banks onto the surrounding towns and countryside. Unlike humans, however, fish have been experiencing floods in their native river habitats for hundreds or thousands of years. And because floods present a strong evolutionarily selective force (you adapt or you die), fish have adapted to survive and even thrive under certain flood conditions.

Salmonids are a good example of a group of fish species that have adapted to local flow regimes...

Read full article on our website >

New Presentation: Wylye Grayling Long-Term Study

Stephen Gregory of the GWCT recently gave a talk at the Avon Piscatorial Society annual Fly Day meeting in Salisbury. The topic of the talk was grayling on the Wylye river in Hampshire and how the population might be affected by flooding, past and future.

You can view the slides from the presentation here:

View Piscatorial Society Fly Day Grayling Talk Feb14 and other presentations by sgregory.

Electro-fishing workshop for MorFish project

The GWCT's Bill Beaumont recently delivered a keynote speech at a workshop on electro-fishing sampling methods and theory.

The talk formed part of the information exchange process with the French team who are working with us on the MorFish project. A group of 40 INRA and Onema staff attended the meeting.

Find out more about electro-fishing here >

New Presentation: Salmon Research at the River Frome

The slides below are taken from a recent presentation covering the salmon research that the GWCT are currently conducting on the River Frome. The presentation took place at West Stafford Village Hall and was given to the Dorset Chalk Stream Club on the 20th December:

You can find out more about the Dorset Chalk Stream Club here and there are photos from the talk on John Aplin's blog.