Brook lamprey · Lampetra planeri

Brook lamprey in England's Rivers

The largest recorded measurement is 22 cm (8.7 in), from Highnam in River Leadon on 18 March 1997.

Median length: 12.4 cm (4.9 in)
Fish measured: 15,637
Named waterways: 600
Latest observation: 30 Jul 2026

Direct individual measurements

Largest brook lamprey by waterway

Ranked by the largest individual measured in EA surveys. The sample size shows how many valid length measurements underpin each waterway's figures.

Rank	River or waterway	Largest	Median	Measured	Measured at
1	River LeadonMidlands	22 cm (8.7 in)	16 cm (6.3 in)	37	18 Mar 1997Highnam
2	River WithamAnglian	21.5 cm (8.5 in)	18.5 cm (7.3 in)	9	7 Sept 2011Great Ponton
3	River Box (Main Reaches)Anglian	21.2 cm (8.3 in)	16.1 cm (6.3 in)	602	25 May 2012Thorington Mill
4	Main River ParrettSouth West	21 cm (8.3 in)	12.5 cm (4.9 in)	812	10 Jul 2009Haselbury Mill
5	Main River ParrettSouth West	21 cm (8.3 in)	16 cm (6.3 in)	84	10 Jul 2009Haselbury Mill
6	River ChelmerAnglian	20.8 cm (8.2 in)	18.3 cm (7.2 in)	44	15 Sept 2016Camsix Farm A
7	Black BrookMidlands	20.6 cm (8.1 in)	11.8 cm (4.6 in)	13	18 May 2012Little Garendon
8	River EcclesbourneMidlands	20.5 cm (8.1 in)	12.5 cm (4.9 in)	134	31 Jul 2014Franker Brook
9	River GowyNorth West	20.5 cm (8.1 in)	13 cm (5.1 in)	41	15 Apr 2003Gwgo05
10	River WenningNorth West	20.5 cm (8.1 in)	12 cm (4.7 in)	20	23 Aug 2013Clapham Station

Equal maximum lengths are ordered by sample size. Measurements are shown as recorded and are not converted into estimated weights.

15,637 fish measured

Measured brook lamprey lengths

The median divides the measured sample in half. This distribution describes surveyed fish, not every brook lamprey living in England.

0–19 mm

20–39 mm

40–59 mm

239

60–79 mm

746

80–99 mm

1924

100–119 mm

3714

120–139 mm

4577

140–159 mm

2831

160–179 mm

1249

180–199 mm

279

200–219 mm

220–239 mm

Only positive individual lengths that pass RiverFish's general measurement checks are included. Each bar covers a 20 mm range.

Latest EA evidence

Latest brook lamprey observations

The ten most recent survey visits that recorded brook lamprey in named waterways.

Date	River or waterway	Survey location	Fish recorded
30 Jul 2026	River Quin	Upstream Griggs Bridge	Not supplied
9 Jul 2026	River Main De Lank	Keybridge	1
8 Jul 2026	River Main Ottery	Penrose	9
6 Jul 2026	Quither Brook	Chillaton	1
1 Jul 2026	River Ruthern	Ruthern Bridge	2
18 Jun 2026	River Western Rother	Coultershaw	6
16 Jun 2026	River Glaven	Upstream Glandford Mill	5
16 Jun 2026	River Western Rother	Terwick Mill	11
15 Jun 2026	River East Looe	Trussel Bridge	14
2 Jun 2026	Swanside Beck	Smithies Bridge (A59)	20

A survey record confirms brook lamprey at that place and time. It does not show present-day abundance or fishing access.

3,751 positive survey visits

Survey distribution

EA surveys recorded brook lamprey at 1,574 locations across 600 named waterways represented on RiverFish.

Region	Waterways	Locations	Survey visits	Latest record
South West	166	374	999	9 Jul 2026
South East	119	435	1,176	30 Jul 2026
Anglian	93	297	785	16 Jun 2026
Midlands	92	205	319	21 Aug 2025
North West	82	142	290	2 Jun 2026
Yorkshire and North East	48	121	182	17 Oct 2023

187 detailed pages

Brook lamprey by river

Open any river-specific page for its measured lengths, largest surveyed individuals, locations and observation history.

Anglian 44 pages

Midlands 22 pages

North West 19 pages

South East 42 pages

South West 53 pages

Yorkshire and North East 7 pages

Cod Beck4 locations · latest 2016 R. Burn3 locations · latest 2017 River Esk4 locations · latest 2017 River Hull3 locations · latest 2006 River Rivelin7 locations · latest 2009 River Tees20 locations · latest 2023 River Worth3 locations · latest 2014

How to read this page

Survey measurements, not angling records

Environment Agency surveys are designed to monitor fish populations. Their largest measurement is not equivalent to a verified rod-and-line record, and the survey sample does not include every river or every brook lamprey.

Waterway groups with administrative or mixed-river labels are excluded from the headline national totals and rankings. Their eligible river-specific pages remain available in the directory so no published destination is hidden.

The fish records use the Environment Agency source snapshot dated 10 August 2026.

How RiverFish handles the data →