Brook lamprey · Lampetra planeri

Brook lamprey in the By Brook main river

Largest measured brook lamprey: 13 cm

The largest brook lamprey measured in Environment Agency surveys of the By Brook main river was 13 cm, recorded at Castle Combe Golf Course (Se-02) on 8 August 2002.

Across 2 measured brook lamprey, the median measured length was 13 cm.

Surveyors recorded weights for 2 brook lamprey. The median was 0.1 oz (0.004 kg) and the largest recorded weight was 0.1 oz (0.004 kg).

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

See brook lamprey records across England →

Most recent observation8 August 2002Castle Combe Golf Course (Se-02) · 1 fish

Largest measured brook lamprey: 13 cm
Median length: 13 cm
Fish measured: 2
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
13 cm	8 Aug 2002	Castle Combe Golf Course (Se-02)	55714
13 cm	8 Apr 1999	Castle Combe Golf Course (Se-02)	23047

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
Castle Combe Golf Course (Se-02)	8 Apr 1999	8 Aug 2002	2
Slaughterford	15 Apr 1999	15 Apr 1999	1
Long Dean	14 Apr 1999	14 Apr 1999	1

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

1999–2002

Survey records by year

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

399

000

001

102

Fish measured by surveyors

Measured length distribution

See how the 2 measured fish were spread across different length ranges.

Smallest: 13 cm
Lower quarter: 13 cm
Median: 13 cm
Upper quarter: 13 cm
Largest: 13 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 2 brook lamprey. This is a subset of the measured fish and may not represent the whole population.

Lightest: 0.1 oz (0.004 kg)
Lower quarter: 0.1 oz (0.004 kg)
Median: 0.1 oz (0.004 kg)
Upper quarter: 0.1 oz (0.004 kg)
Heaviest: 0.1 oz (0.004 kg)

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

More fish in this river

Explore the By Brook main river

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

Brown / sea trout Bullhead 3-spined stickleback Minnow Stone loach 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 →