Brook lampreys began spawning this week and we took these photos of a group spawning the Youghal River which flows into Lough Derg. We are also monitoring sites on the River Mulkear, but have not recorded any activity here due to the high water levels. The photos below were taken on the first of April, and this was the first brook lamprey spawning activity that we recorded this year.
The brook lamprey Lampetra planeri is the smallest of the the three Irish lamprey species. It is non-parasitic and does not migrate to the sea like the other two species.The adults spawn during the period March to June (depending on water temperature), and the ova are deposited into depressions (nests) dug in the riverbed. They are communal spawners (like river lampreys) and a number of males mate with one female. The larvae (known as ammocoetes) live for three to seven years in the sand or mud, and filter organic matter from the water. As they mature they develop eyes and the sucker-like mouth, and as sexual maturity is approached they stop feeding entirely. brook lampreys doe after spawning.
The brook lamprey is relatively widespread and common in Ireland, but is increasingly affected by impacts such as river drainage works and water pollution. They are very sensitive to obstacles in rivers, including salmon counters, hydrometric weirs and even bridge underpinning works. We should not take our brook lamprey populations for granted, and brook lampreys have declined in many parts of Europe. Brook lampreys are a key conservation interest of the Lower River Shannon Special Area of Conservation.