It is now widely recognised that wild salmon face many challenges during the time they spend at sea. Over the past two decades, an increasing proportion of North Atlantic salmon are dying at sea during their oceanic feeding migration – though we don’t yet fully understand why.
The research carried out under the EU-funded SALSEA Merge (Salmon at Sea) programme (which also received funding from AST) showed conclusively that, during the part of their life-cycle spent at sea, Atlantic salmon are pelagic fish, swimming alongside commercially-fished species such as herring, mackerel and blue whiting, and sharing the same ocean environments. They are therefore at risk from the fisheries targeting these species. This is particularly true of the shoals of post-smolts heading for oceanic feeding grounds.
“Given the size of the trawls and purse seines used by the commercial fleets, we believe that there is a real risk that shoals of migrating post-smolt salmon could unwittingly be intercepted by the fishery and significant numbers of young salmon harvested as a by-catch,” said Professor Whelan.
“Despite research programmes such as SALSEA, there are still large gaps in our knowledge of exactly where these fish go. Hence the very practical requests I made to the Pelagic RAC in respect of the survey and research work that needs to be urgently undertaken, and to ask for their support.
“Including Atlantic salmon in the on-going routine monitoring of commercial pelagic species should not cost a lot, and would vastly increase our knowledge of exactly which ‘migration corridors’ salmon use,” continued Professor Whelan.
“We would then be in a much stronger position to recommend actions to manage and protect those corridors during the relatively short period during which salmon migrate. There was a very keen interest at the meeting in how the salmon, which roams far and wide across the pelagic zone but ultimately returns to its river of origin, is being used by scientists to track the abundance and quality of the available food in the areas which it visits. In essence our wild salmon are self-homing miniature probes which bring back a vast amount of data on the health of the ocean and the availability of common food sources.
SALSEA has shown how climate change is impacting on the survival of salmon at sea and clearly it is also affecting the abundance and location of food for species such as herring and mackerel. In addition, SALSEA has refined and developed new genetic fingerprinting technology which, if applied to the commercial pelagic species, could separate out what are now regarded for management purposes as stocks into self-reproducing populations of fish. Such a breakthrough would greatly refine how we manage a wide range of vitally important commercial species and ensure more accurate control and stock rebuilding measures.”
“We have also learned, through genetic analysis, that different regional stocks of salmon use different routes to the feeding grounds, and indeed feed in different areas,” added AST Chief Executive Tony Andrews.
“At present, the greatest challenge to salmon conservation is our inability to predict which regional – and river – stocks are finding good food sources at sea. The insights we would get from an on-going programme of routine monitoring of salmon as part of the ‘pelagic family’ would assist greatly in this, to the extent that in the future we’d hope to be able to give fishery managers reasonably accurate predictions of how many fish they could hope to see returning to their river.”
“I was very impressed with the interest shown by the Pelagic RAC chairman Iain MacSween and members of the Executive Committee in the work of the SALSEA team. I was also taken with the generous spirit of cooperation shown by members of the RAC in offering to work closely with us in the future to further our understanding of the pelagic zone and the wide range of fish and other creatures living in this complex, dynamic environment,” concluded Professor Whelan.
