Brook lamprey · Lampetra planeri

Brook lamprey in the Itchen Navigation

Largest measured brook lamprey: 12.5 cm

The largest brook lamprey measured in Environment Agency surveys of the Itchen Navigation was 12.5 cm, recorded at Ham Farm on 23 August 2017.

Across 6 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 Itchen Navigation.

See brook lamprey records across England →

Most recent observation27 October 2025Ham Farm · 1 fish

Largest measured brook lamprey: 12.5 cm
Median length: 11.7 cm
Fish measured: 6
Survey locations: 2

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
12.5 cm	23 Aug 2017	Ham Farm	151345
12.5 cm	23 Aug 2017	Ham Farm	151345
11.8 cm	23 Aug 2017	Ham Farm	151345
11.6 cm	23 Aug 2017	Ham Farm	151345
11.5 cm	23 Aug 2017	Ham Farm	151345
8.2 cm	23 Aug 2017	Ham Farm	151345

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
Ham Farm	1 Sept 2009	27 Oct 2025	8
Shawford navigation eel index	22 Sept 2009	22 Sept 2009	1

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

2009–2025

Survey records by year

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

209

010

111

012

113

014

015

016

117

018

119

020

021

122

123

024

125

Fish measured by surveyors

Measured length distribution

See how the 6 measured fish were spread across different length ranges.

Smallest: 8.2 cm
Lower quarter: 11.5 cm
Median: 11.7 cm
Upper quarter: 12.3 cm
Largest: 12.5 cm

0–99 mm

100–199 mm

Lengths are direct survey measurements rather than anglers’ catches.

More fish in this river

Explore the Itchen Navigation

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

European eel Pike Minnow Roach Grayling Atlantic salmon

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 →