Salmon dilemma

The Scotsman deserves warm congratulations for publishing lately a series of important ­articles relating to the aquatic environment, at a time when the government is considering the Aquaculture and Fisheries Bill.

The subject of the most recent (11 December), the conservation of spring-running salmon, is a small fraction of the problem.

According to United Nations (Fisheries & Aquaculture Organisation 2012) data on worldwide fishery landings between 1950 and 1990 have shown progressive declines in average fish size because the upper part of the food web is being fished out. This effect is known as “fishing down the food web”.

The consequence, if this is allowed to continue, will be complete collapse of fish populations. It is not surprising that sea-bird colonies are in serious decline. Acidification, pollution and rises in global temperatures do not help.

Marine Protection Areas, if planned on sufficient scale, offer some hope but they will need to be flexible given that fish populations are not remaining static; ocean warming is causing them to move towards the poles in both hemispheres. Most independent fisheries scientists consider that aquaculture, as currently conducted, is not the answer to world food supply. They believe it is unsustainable for a number of reasons. Fish farms are major polluters of the marine coastal environment.

They culture not only fish but also fish diseases, including the sea-lice parasites that have destroyed native fish populations and are continuing to do so.

Thirdly, they aggravate the problem of overfishing by creating an enormous demand for fish meal and fish oils for the manufacture of fish pellets. It is said to take three tons of fish meal to grow one ton of farmed salmon. Does the government have the courage to address these issues effectively?

(Prof) Vaughan 
Ruckley

Mayfield Terrace

Edinburgh

Your report, “Ban anglers from catching salmon in spring, urge fish farm experts” (11 December), does not reflect the important conservation measures already adopted by District Salmon Fishery Boards. They take their responsibilities and obligations in terms of conserving salmon stocks very seriously.

In the past 20 years, boards have introduced a raft of measures to protect salmon numbers, in particular those of spring salmon. In 2011, according to the official statistics, 6,116 spring salmon were caught by anglers. Of these 5,554 (or 91 per cent) were released back into the water. Just 562 were killed by anglers, of which fewer than 300 were taken on Special Area of Conservation rivers.

Ultimately the funds for fisheries management in Scotland come from angling activity. Spring-salmon angling extends the rod season and these early months are often the difference between ghillies and others in associated tourist angling businesses being employed year round as opposed to being employed on a seasonal basis.

(Dr) Alan Wells

Association of Salmon Fishery Boards

Canning Street

Edinburgh