Harbour seals serious menace to salmon stocks
By Ralph Shaw - Comox Valley Record - November 02, 2007 | | |
It is not the purpose of this column to pick a fight with anybody or to offend people’s opinions. It is solely to try to point out the serious threat that harbour seals pose to discreet stocks of salmonids in coastal waters.
In 1986 the report of the Royal Commission on Seal and Sealing was released. In Volume 3 there is the following summary statement on the status and stocks of harbour seals on the Pacific Coast:
1) The current population of harbour seals is large and possibly growing; it is probably in the range of 45,000 to 60,000 animals.
2) Unless it has stabilized very recently, the population is still increasing, probably by about 10 per cent per annum.
3) It is not possible to determine at what level the population will stabilize if it continues to be protected.
4) Hunting for bounties and hunting by fishermen in the years prior to 1970 did not endanger the harbour seals population, since it remained capable of a rapid natural increase when hunting ceased.
5) Unless the population has already been affected by changed environmental conditions, it can sustain an annual kill of at least 3,000 animals, and perhaps as many as 6,000, without risk.
6) The environmental effect caused by humans which seems most likely to have an adverse impact on the harbour seal population is pollution, particularly by chlorinated hydrocarbons, but there is no evidence on any significant effect of these pollutants at present.
Based on the information of the first two points and extrapolation of the growth in numbers based on a population base of 50,000 animals and an annual increase of 10 per cent over the past 21 years, the figure I came out with was a staggering 321,434 seals. I am not a statistician so I seriously question my figures, but annual increases of the magnitude reported in the commission’s hearings are based on the best science available at the time of the report.
In discussion with members of the Sport Fishery Advisory Board, I am told DFO estimates the current coast-wide population at somewhere between 125,000 and 150,000.
In the intervening period from 1986 to 2007 we have witnessed some serious declines on salmon populations throughout the coast. The reasons for the declines are many, but one significant trend stands out – seals are impacting on salmon in estuaries as never before.
Peter Olesiuk, seal specialist with DFO, reported at a meeting last spring that harbour seals probably consumed 3.1 million chum salmon smolts in the Puntledge River during the spring migration. This will equal the planned annual output for the hatchery this year. It raises the question – Are we raising salmon in hatcheries to feed harbour seals?
It was reported at the local Sport Fishery Advisory Committee on Oct. 10 that all estuaries in our region face similar problems of seal predation. Black Creek, which is a coho indicator stream, has a reported 200 harbour seals in its estuary.
In point five of the conclusions it was pointed out that an annual kill of 3,000 animals in the bounty program did not effect the viability of the seal population and that the removal could be as high as 6,000. This was based on a population estimated at 45,000 to 60,000. Our current population is certainly on the order to three fold of the 1986 numbers.
We have been informed there will be no cull of seals in the river this year. The proposal at the moment is to expand the idea of controlling seals’ eating habits by experimental electric fences next year. In the meantime our fish stocks continue to decline.
In face of declining fish populations and declining budgets from DFO it seems to me that if we are to have a hope of rebuilding our salmon stocks we must reduce the in-river predation by seals. I propose that we have an annual cull of seals in rivers under attack by these intelligent, adaptive predators.
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Char & Ziggy