BROOK LAMPREY FOUND IN SUFFOLK Eric Parsons
The Brook Lamprey, Lampetra planeri, which rarely exceeds 18 c fully grown, is considered to be uncommon if not rare in Suffolk, but it species that has been positively identified in the County during the spring 1991, thanks to the curiosity of two observant civil engineering contracto engaged upon river work. What they witnessed was the nest building a spawning behaviour of our smallest species of Lamprey in the Mill Rive The three native species that are thought to occur in Suffolk are the parasitic Sea Lamprey, Petromyzon marinus, the Lampern or Lamprey, Lampetrafluviatilis,and a non-parasitic species, the Brook Lamprey, Lampetra planeri. The Sea Lamprey is the largest of th growing to a length of 70cm. or more and it can be expected to be moving upstream in rivers to spawning grounds in May or June. All three species are known to spawn during daylight in relatively shallo water in the parts ofriverssometimes referred to as 'trout streams'. They the places where the gradient is such that fast flowing water has reduced river bed to bare sand and pebbles. Nest construction begins with lampr lifting stones from the nest site to create depression in the river bed. Wh site has been cleared of stones sufficiently, a secondary excavation beg Attached to a suitable stone, the lampreys vibrate their bodies rapidly short bursts within the nest, pounding and fanning smaller stones and gra into the current to be carried downstream. Spawning begins when the female, anchoredfirmlyto a stone in thefloorof the nest, is gripped by male on the head or forequarters and, in aflurry,the male entwines vibrating female causing a few eggs to be expressed from her body. These simultaneously fertilised by a plume of sperm from the male. The diminu Brook Lamprey has been seen to engage in the sexual act over a hun times a day for nine days. Brook Lampreys die after spawning.
Hardisty, M. W. & Potter, I. C. (1971). The Biology of Lampreys s Press, London. Maitland, P. S. (1972). A Key to the Freshwater Fishes of th Freshwater Biological Association, Ambleside. Eric Parsons, 41, Dover Road, IPSWICH, IP3 8JQ.
Trans. Suffolk Nat. Soc. 28 (1992)
Plate 4: One of several Brook Lampreys (Lampetra planen) Mill River, 12th April 1991. (p. 10).
nest-building in about 35 cm. of water in the