Lamprey (Lampetra)

An ancient type of fish with a simple skeleton of cartilage, primitive mouthparts instead of jaws, horn like teeth, and no paired fins or protective plates over their gills.

Long and thin like eels; the obvious difference is that eels have a distinct head with a pair of fins behind it and protective covering of the gills. Lampreys have no distinct head, and the gills are exposed as a row of holes along the front sides of the body.

Three species of Lamprey live in the River Eden; the Brook Lamprey, the River Lamprey and the Sea Lamprey

The Brook Lamprey (Lampetra planeri) also known as Planer's Lamprey.

Description: Length: up to 25cm

Habitat: slow moving watercourses with substrates of fine sediment.

Lifecycle: spawning March to June.

A shallow excavation (a redd) is made in the sandy/gravely substrates of small rivers and streams. The female lays up to 1,200 eggs (1mm diameter) into the shallow nest and the eggs are fertilised soon after laying.

Female Brook Lampreys die ten to fifteen days after spawning; males live for twenty to forty days.

The eggs hatch three weeks later. The larvae (prides) spend three to seven years buried in sand, mud or clay at the bottom of the river feeding on tiny particles of organic matter and diatoms (simple microscopic organisms).

In the autumn and winter prior to spawning the blind and worm like prides emerge from the bottom of the river to mature, developing eyes and an oral sucker. When mature their digestive organs waste away and stop functioning, and so they do not feed throughout adulthood. They rest for a time, and then migrate upstream to spawn.

The Sea Lamprey (Petromyzon marinus)

Description: Length: up to 1 metre. Weight: up to 2kgs.
A grey-green colour with darker mottling and a yellow-white underside, it has a round mouth which acts as a sucker with many concentric rows of horny teeth.

Habitat: European coastal waters, migrating up rivers in March - April.

Lifecycle: Spawns in May to July in rivers 1 metre deep with substrates ranging from sand to stones.

The male creates a redd into which the female deposits 60,000 to 300,000 eggs, each of about 1mm in diameter, that are then fertilized. Soon after spawning they die.

The larvae (ammocoetes) hatch in 8 to 20 days, and live in muddy backwaters, buried in the substrate, and feeding on suspended organic matter for up to five years.

They mature and migrate downstream to the sea where they live for a few more years, feeding parasitically on large fish.

The River Lamprey (Lampetra fluviatilis), also called the Lampern.

Description: Length: up to 50cms
A dark blue - grey to green - grey coloured body with a silvery white belly.

Habitat: European coastal waters from the Mediterranean to Norway.

Diet: It is parasitic; attaching itself to other fish using its disc like mouth and feeding on the blood of its host.

Lifecycle: migrate to the spawning site in the spring; attaching themselves to other anadromous fish species to get a free ride upstream.

En route they change colour to a deep bronze, digestive organs degenerate, and they become detached from their hosts. As they continue to swim upstream they lose their sensitivity to light.

The male excavates a redd using his mouth and wriggling his body. As the female lays the eggs the male fertilises them instantly. Each mating lasts a few seconds and only a small number of eggs are laid. More males mate with the same female, who may lay anything between 10,000 and 25,000 eggs. Lampreys die soon after spawning.

The larvae (ammocoetes) hatch between nine and twenty days later, they absorb their yolk sacs and leave the redd for a quiet muddy backwater. Here they bury themselves in the sand/silt, forming tunnels. They spend the first four to six years of their lives here.

They are blind and have no suctoral apparatus. They feed by protruding their mouths a little above the surface of the river bed, facing against the direction of the current, sifting organic debris and microrganisms (tiny creatures and plants) from the water.

On maturing, they migrate to the sea for two summers before returning to the river to spawn.