As part of the Loughs Agency’s annual redd counting on the River Roe and its tributaries in Northern Ireland, underwater cameras were successfully deployed and have captured footage of salmon spawning activity.
Mark McCauley, freshwater fisheries biologist with the agency, said the footage shows some of the “varied and complex” lifecycle of the salmon.
“A female salmon begins to deposit her eggs in a redd as an adult male moves alongside to fertilise them. A female salmon produces approximately 1,100 eggs per kilogram of body weight,” he said, describing the footage.
“The male has a very distinctive hooked lower jaw called a kype. This is a characteristic displayed by adult males at spawning time. It is assumed to establish hierarchy among males, with those displaying larger kypes thought to be more dominant.
“The female then uses her tail to cover the fertilised eggs with gravel.
“The footage shows a parr moving over the area quickly afterwards, probably hoping to eat any eggs that are not covered before being driven off by the larger male.
“There are some instances of precocious parr, sometimes referred to as sneaker males. These are sexually mature salmon parr who will try to fertilise some of the eggs in an attempt to pass on some of their genes.
“This is all part of the varied and complex life-history strategies of Atlantic salmon.”
Spawning is a sensitive time of year for returning salmon and any disturbance can take them off the redd. Redds can also be damaged if stepped on. Therefore, the Loughs Agency advises against members of the public entering the river to view this activity.
