Sunday, 14 September 2014

An electrifying day spent on the river Frome!

The beautiful river Frome in Dorset

I spent a most enjoyable day last week with the GWCT research fisheries team at East Stoke in Dorset, catching and tagging Salmon Parr on the river Frome. Each September the team works virtually non-stop to catch and tag at least 10,000 of these little fish, which as I discovered first hand, means long hours of hard work!

The scientists catch the young fish by putting an electric field, created by a generator situated in a small boat pulled along behind, into the water so that the fish are temporarily incapacitated (called Electro-fishing) and thereby making them easier to catch in a net. Whoever is working the nets has to have lightening (get it!) reactions because the fish are dazed for just a few seconds, as demonstrated by the captured fish which are swimming around in the bucket quite normally almost immediately they are put in.

Meanwhile on the bank, a mobile makeshift “laboratory” has been set up to process the fish caught. They are weighed and their length is measured and recorded straight onto a laptop. Then they are tagged – a minute little chip inserted into them – these are known as Passive Integrated Transponder (PIT) tags.

Equipment on the river can now record the passage of the PIT tagged fish as they pass below on their way out to sea and in fact gives the scientists the ability to identify and follow individual fish through their complete life-cycle. Atlantic salmon numbers have dropped by 70% in some areas and this long term project is aiming to tell us why this may have occurred.

The day I went there were two teams of 7 in action and between 8.30am and 7pm, they caught around 700 Salmon Parr whose details were all fully recorded. Once tagged, all were successfully released back into the river.

One little Parr from the river Frome, just like those we caught last week, made the epic migratory journey to a Fish Market in Sisimuit on the west coast of Greenland. On October 6th 2009, the fish was picked up during a sampling programme organised by the North Atlantic Salmon Conservation Organisation (NASCO).

The little Salmon Parr was recorded swimming past the GWCT detection equipment on the night of 24 April 2008 on its way out to sea and was estimated as being about 14.9 cm long. By October 2009, the salmon had grown over 50 cm in length during the 500 plus days it had spent at sea, and now it measured in at 67.9 cm and weighed just over 9lb! We really do live in an amazing world do we not!!

What’s also really great about the September tagging programme is that a number of students who are currently studying such courses as fisheries management or freshwater biology, come along to help and in the process gain invaluable practical experience. Don’t let it be said that students doss about, generally not doing much, as the guys who are currently working on the project (Two from Bridgewater college and one each from Portsmouth University and Sparsholt college) were not only charming, but also worked their socks off!

They get superb tutoring too, as head of GWCT fisheries Dylan Roberts and senior fisheries scientist Bill Beaumont were both on hand to happily pass on their massive wealth of incredible knowledge. So much of this know-how only comes through years of experience of working with fish - such as when Bill casually pointed out to me the marks on the side of one little fish. "See this" he said, "they are the marks left by a Kingfisher's beak - one that got away"!  You don't pick that sort of thing up in a classroom!    

I had a brilliant day and learnt so much. I have put a few more pictures below for you to look at. This really is such an incredibly fascinating project that I'm sure you would like to find out more about it too. If so, go to:


Electro-fishing a side channel of the river Frome

Part of one of the teams in action

The boat with the generator and kit

Not a bad location for a laboratory! 

A Salmon Parr

Senior Fisheries Scientist - Bill Beaumont - such a wealth of knowledge

Other fish are caught too - such as this good sized Brown Trout

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