Found a Tagged Fish?
Find out how to keep and report a tagged fish (a reward is offered).
Fish Tagging in Shetland
The NAFC Marine Centre tags fish around Shetland to collect information on their distribution, movements and growth.
Why Tag Fish?
Fish are tagged to obtain information on their movements and growth. Both pieces of information can contribute to the more effective management of fish stocks.
Tags identify individual fish so that when they are caught again we can work out how far they have traveled since they were tagged, and how much they have grown.
How are Fish Tagged?
The fish tagged by NAFC are caught by our fishing vessel Atlantia II. The Atlantia's trawl net is fitted with a specially made 'live-fish cod-end' - a watertight bag fitted inside the net - so that that the fish are kept in water while the net is brought on board. The fish are then transferred to tanks of seawater to await tagging.
Each fish is measured and tagged with a 'T-bar' tag (Hallprint) anchored into its back muscle before being released back into the sea. Each tag bears a unique number which is recorded along with its release location, species and length.
What species are tagged?
We have tagged a number of species, including:
- lemon sole
- monks (anglerfish)
- skates and rays
How many fish have you tagged?
Between 2013 and 2017 we tagged 13,427 individual fish (see Table below).
How many tagged fish have been caught?
1,044 of the fish tagged had been recaptured and returned by the end of 2019 (8% of the total). Most fish were recaptured within one year of being tagged.
How far have the tagged fish traveled?
There has been considerable variety in the distances traveled, both between species and between individuals of the same species. Most lemon sole were caught fairly close to where they were tagged, while some plaice traveled much further. The greatest distance was for a plaice which was recaptured 172 km from where it was tagged (measured in a straight line) after 802 days.
Maps showing the distances traveled by tagged plaice (left), lemon sole and monks (anglerfish; right). Straight lies connect positions of release and recapture and do not represent the actual paths taken by the fish. For more details see the report Movement and Growth of Commercially Important Juvenile Fish in Shetland Waters.
How much have the tagged fish grown?
Rates of growth have varied between species. Plaice, lemon sole and megrim have typically grown by between 1 and 2 cm per year between release and recapture, although that depends on their length when they were tagged (smaller - or younger - fish tend to grow faster). Monks have typically grown by about 10 cm per year.
This tagging work has been undertaken under a series of funded projects. The principal funders included:
- the Scottish Government (2013)
- the European Fisheries Fund (2014)
- the Scottish Fishing Industry Science Alliance (FISA; 2015)
- Shetland FLAG (SCO1712)
- Poster: Tagged Fish Wanted (pdf)
- Poster: Fish Tagging Study on Data Limited Stocks in Northern Waters (pdf)
- Report: Movement and Growth of Commercially Important Juvenile Fish in Shetland Waters, Shetland FLAG Project (SCO1712) report – June 2019
- 4 July 2016: Valhalla Tags a Prize