Brook lamprey · Lampetra planeri

Brook lamprey in the River Thet

Largest measured brook lamprey: 17.5 cm

The largest brook lamprey measured in Environment Agency surveys of the River Thet was 17.5 cm, recorded at Snetterton Gravel Pits on 5 August 2009.

Across 9 measured brook lamprey, the median measured length was 13.3 cm.

Surveyors recorded weights for 9 brook lamprey. The median was 0.1 oz (0.004 kg) and the largest recorded weight was 0.7 oz (0.02 kg).

RiverFish uses Environment Agency survey measurements rather than rod-and-line angling records. These figures show fish measured during EA surveys of the River Thet.

See brook lamprey records across England →

Most recent observation22 October 2024Manor Farm Shropham · 1 fish

Largest measured brook lamprey: 17.5 cm
Median length: 13.3 cm
Fish measured: 9
Survey locations: 3

Individual EA measurements

Largest measured brook lamprey

The largest individual measurements in this river and species dataset. Equal measurements are retained as separate surveyed fish.

Length	Survey date	Survey location	Survey ID
17.5 cm	5 Aug 2009	Snetterton Gravel Pits	118289
16.7 cm	1 Aug 2012	Snetterton Gravel Pits	132568
14.8 cm	22 Oct 2024	Manor Farm Shropham	167733
13.4 cm	11 Oct 2018	Snetterton Gravel Pits	153724
13.3 cm	11 Oct 2018	Snetterton Gravel Pits	153724
13.2 cm	11 Oct 2018	Snetterton Gravel Pits	153724
12.4 cm	11 Oct 2018	Snetterton Gravel Pits	153724
10.9 cm	11 Oct 2018	Snetterton Gravel Pits	153724
10.7 cm	11 Oct 2018	Snetterton Gravel Pits	153724

Lengths are direct survey measurements. RiverFish does not estimate fish weights from length.

Explore the river

Where brook lamprey were found

Each point marks a survey location with at least one brook lamprey record.

Choose a point on the map to see what was recorded there.

Map points are approximate and don’t show fishing access. Check local permissions before visiting.

Place surveyed	First recorded	Last recorded	Visits finding brook lamprey
Manor Farm Shropham	22 Oct 2024	22 Oct 2024	1
Snetterton Gravel Pits	5 Aug 2009	11 Oct 2018	3
Bridgham Bridge	20 Nov 1995	20 Nov 1995	1

Choose a point or table row to see the location. More survey visits can mean more records, but not necessarily more fish.

1995–2024

Survey records by year

Each bar shows how many survey visits recorded brook lamprey that year.

195

096

097

098

099

000

001

002

003

004

005

006

007

008

109

010

011

112

013

014

015

016

017

118

019

020

021

022

023

124

Fish measured by surveyors

Measured length distribution

See how the 9 measured fish were spread across different length ranges.

Smallest: 10.7 cm
Lower quarter: 12.4 cm
Median: 13.3 cm
Upper quarter: 14.8 cm
Largest: 17.5 cm

100–199 mm

Lengths are direct survey measurements rather than anglers’ catches.

Fish weighed by surveyors

Measured weight summary

Recorded weights were available for 9 brook lamprey. This is a subset of the measured fish and may not represent the whole population.

Lightest: 0.1 oz (0.002 kg)
Lower quarter: 0.1 oz (0.004 kg)
Median: 0.1 oz (0.004 kg)
Upper quarter: 0.2 oz (0.0051 kg)
Heaviest: 0.7 oz (0.02 kg)

These are direct individual weights recorded by Environment Agency surveyors. Combined bulk weights are not included.

More fish in this river

Explore the River Thet

Compare other species with enough survey and measurement data for a detailed page.

Roach Pike Gudgeon Perch Dace European eel

Before you fish

Good to know

These are past survey records, so the fish present today may be different. Map points are approximate—check local access, permissions and fishing rules before visiting.

Learn how RiverFish uses the data →