What's happening to Atlantic salmon? (2)

Continues interview with Niall Ó Maoiléidigh, the outgoing Chair of the ICES Working Group on North Atlantic Salmon.

We are becoming increasingly aware of the possible impacts of marine fisheries on salmon survival, particularly at the post-smolt stage (up until August / September of the first year at sea).

Do salmon get caught as a by-catch in marine fisheries?

For some years, the Norwegians have been developing techniques to sample post-smolts at sea using modified surface trawls. This work has provided us with some exciting new insights into the oceanic migrations of European salmon in the first few months at sea when mortality rates are likely to be very high.

One of the more significant findings from this experimental work has been that post-smolt catches are generally made with large mackerel by-catches.

This has raised the possibility that similar commercial trawl fisheries for mackerel in the same areas could also be taking post-smolts. Initial estimates provided by the Working Group in 2002 suggest that this could be a significant proportion of the total recruits available. It is certainly an area of investigation, which we need to pursue in association with our colleagues in other fisheries Working Groups.

Have there been any recent breakthroughs in our understanding of salmon life histories?

The whole area of marine survival has been regarded as a "black hole" until very recently. Studies undertaken, in particular by Norwegian and Scottish scientists, to design and set up marine sampling programmes have paid enormous dividends in a relatively short time. These studies have provided new information on migration routes, timing, and oceanographic factors, which influence the early migrations.

These studies have been complemented by highly innovative work in North America and Europe using data storage tags on kelts (spent salmon returning to sea after spawning) and nearshore tracking systems, again using new electronic tags.

We have also learned a lot recently by better use of existing data in new modelling and simulation approaches, particularly in the Northeast Atlantic area which has had the benefit of nearly three years of an EU-funded concerted action (SALMODEL: A coordinated approach towards the development of a scientific basis for management of wild Atlantic salmon in the Northeast Atlantic).

While a lot is happening or beginning to happen, it will take some time to bring all of this new information into a more global understanding of the key processes involved in salmon migration and marine survival. But the first steps are now being taken.

"...we need to give salmon stocks every chance to respond to the improved conditions...."

How do you think the current decline in salmon stocks could be halted?

One of the worrying features of the continuing decline in recruitment is that despite all the very significant closures or restrictions in fisheries on both sides of the Atlantic and in the mixed stock high-seas fisheries of West Greenland and the Faroes, the expected benefits from these measures have not materialised in all areas.

Obviously, without these measures the situation would be even worse, but it must be acknowledged that there have been huge efforts in recent years to allow more fish to spawn.

While marine conditions for salmon have shown some improvement in recent years - in terms of more sea area with optimum temperatures - it appears that the expected response from the stocks to this increase has been slow or has not yet occurred.

Clearly, we need to give salmon stocks every chance to respond to the improved conditions and this can only be done by meeting conservation limits.

This is likely to mean even greater restrictions in fisheries, and in some areas stock rebuilding will be necessary. While it is important to understand how marine conditions affect mortality, action must be taken to ensure the best use of the stocks that are available.

For further information about the Atlantic salmon please try the following:
http://www.asf.ca/
http://www.asf.ca/Journal/2002/02spr/index.html
http://www.nasco.org.uk/

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