Brook lamprey · Lampetra planeri

Brook lamprey in the River Main Yealm

Largest measured brook lamprey: 15.5 cm

The largest brook lamprey measured in Environment Agency surveys of the River Main Yealm was 15.5 cm, recorded at Treby Ham on 21 August 2015.

Across 70 measured brook lamprey, the median measured length was 11.7 cm.

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

See brook lamprey records across England →

Most recent observation18 August 2023Treby Ham · 4 fish

Largest measured brook lamprey: 15.5 cm
Median length: 11.7 cm
Fish measured: 70
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
15.5 cm	21 Aug 2015	Treby Ham	146030
15.5 cm	31 Jul 2014	Treby Ham	142071
15.2 cm	31 Jul 2014	Treby Ham	142071
15.1 cm	31 Jul 2014	Treby Ham	142071
14.9 cm	21 Aug 2015	Treby Ham	146030
14.4 cm	31 Jul 2014	Treby Ham	142071
14.1 cm	8 Aug 2019	Treby Ham	155692
14 cm	8 Aug 2019	Treby Ham	155692
13.9 cm	13 Aug 2013	Treby Ham	137862
13.6 cm	8 Aug 2019	Treby Ham	155692

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
Treby Ham	23 Jun 2009	18 Aug 2023	8
Potsons Wood	24 Jul 2007	14 Jul 2022	6
Puslinch Bridge	18 Jun 2009	7 Aug 2018	5

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

2007–2023

Survey records by year

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

107

008

309

010

111

212

113

314

115

116

117

218

119

020

021

122

123

Fish measured by surveyors

Measured length distribution

See how the 70 measured fish were spread across different length ranges.

Smallest: 4 cm
Lower quarter: 9.2 cm
Median: 11.7 cm
Upper quarter: 13 cm
Largest: 15.5 cm

0–99 mm

100–199 mm

Lengths are direct survey measurements rather than anglers’ catches.

More fish in this river

Explore the River Main Yealm

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

Brown / sea trout Atlantic salmon European eel Bullhead Minnow Flounder

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 →