#Angling - An international fisheries biologist has suggested a novel approach to boosting numbers of wild Atlantic salmon in Irish rivers — by moving wild fry from more abundant areas to weaker spots within a catchment.
Dr Kyle Young, a research associate from the University of Zurich, was recently invited to give a presentation as part of the Inland Fisheries Ireland (IFI) Research Seminar Series, at which he outlined his proposal for translocation of salmon fry.
Natural survival bottlenecks are experienced by Atlantic salmon through each stage of its lifecycle, from egg to fry, fry to parr, parr to smolt and so on, he outlined. Under natural conditions, the vast majority of wild salmon fry do not survive to become parr.
These so called “doomed majorities” can be present in sections of rivers with an initial abundance of emergent salmon fry, whose subsequent population size is constrained by density-dependent mortality and by the carrying capacity of the habitat.
Dr Young proposes that such fry could be translocated from these areas to low or non-productive sections of the same river where suitable habitat is present, in an effort to potentially boost the overall production of native wild salmon populations.
This approach may minimise the unintended negative consequences of more conventional salmon stocking programmes where wild salmon broodstock are taken from spawning areas and eggs fertilised in the hatchery.
Hatchery-origin fish are also typically less well-adapted to thrive than their wild compatriots and the overall fitness of the wild component of a population may be compromised through lower overall survival, interbreeding and competition for resources with stocked fish.
IFI’s head of R&D Dr Cathal Gallagher said: “We were delighted to welcome Dr Young to our headquarters in Citywest to further explore the potential of this novel proposal to boost wild Atlantic salmon populations.
“This iconic species is of both major conservation and socio-economic importance to Ireland. Although wild salmon are widely distributed in Irish freshwaters, their long-term sustainability remains under continued threat from a variety of factors. These include habitat degradation, issues related to aquaculture, oceanic and climatic change, pollution, illegal fishing and over-fishing.”
Following the seminar, Dr Young visited the National Salmonid Index Catchment (NSIC) at the River Erriff, the Galway Salmon Fishery and the Cong hatchery facility to further discuss his theorised approach to salmon stocking with IFI management, field staff and researchers.
IFI are discussing the possibility of undertaking experimental trials with this novel approach to boost juvenile salmon production upstream of their trapping facilities in the Erriff catchment.