RiverFish

Brook lamprey · Lampetra planeri

Brook lamprey in the Swanside Beck

Largest measured brook lamprey: 16 cm

The largest brook lamprey measured in Environment Agency surveys of the Swanside Beck was 16 cm, recorded at Smithies Bridge (A59) on 13 June 2016.

Across 28 measured brook lamprey, the median measured length was 13.3 cm.

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

See brook lamprey records across England →

Most recent observation2 June 2026Smithies Bridge (A59) · 20 fish
Largest measured brook lamprey
16 cm
Median length
13.3 cm
Fish measured
28
Survey locations
1

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.

LengthSurvey dateSurvey locationSurvey ID
16 cm13 Jun 2016Smithies Bridge (A59)148213
15.8 cm2 Jun 2026Smithies Bridge (A59)181996
15 cm2 Jun 2026Smithies Bridge (A59)181996
14.9 cm13 Jun 2016Smithies Bridge (A59)148213
14.8 cm2 Jun 2026Smithies Bridge (A59)181996
14.5 cm13 Jun 2016Smithies Bridge (A59)148213
14.4 cm2 Jun 2026Smithies Bridge (A59)181996
14.2 cm2 Jun 2026Smithies Bridge (A59)181996
14 cm2 Jun 2026Smithies Bridge (A59)181996
14 cm14 Jul 2014Smithies Bridge (A59)142297

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 surveyedFirst recordedLast recordedVisits finding brook lamprey
Smithies Bridge (A59)7 Jul 20042 Jun 202610

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

2004–2026

Survey records by year

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

Fish measured by surveyors

Measured length distribution

See how the 28 measured fish were spread across different length ranges.

Smallest
8.6 cm
Lower quarter
12.2 cm
Median
13.4 cm
Upper quarter
14.3 cm
Largest
16 cm

Lengths are direct survey measurements rather than anglers’ catches.

More fish in this river

Explore the Swanside Beck

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

Brown / sea trout Atlantic salmon 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 →