Proposed introduction of salmon condemned

Press, Volume CXI, Issue 32566, 27 March 1971, Page 9

Proposed introduction of salmon condemned

(By D. J. HUGHEY)

It is heartening to know that the introduction of coho, better known as silver salmon, is to be the subject of a thorough investigation by the Marine Department before any releases are made in New Zealand waters. That such an introduction can even be contemplated is beyond comprehension.. The facts learnt from the Glenriffe salmon trap have reached a stage where

management based on scientific evidence is now possible. The last annual report of the North Canterbury Acclimatisation Society reproduced two articles by the Marine Department that should leave no member in doubt about what to do. We have only one species in our rivers, the quinnat (king of the Pacific) salmon. Easily the biggest of the

five species, it is also the best because, it is successfully acclimatised and disease-free. Development is held back only by lack of proper management; no costly and perhaps disastrous new introduction is necessary. The following extracts taken from the society’s own annual 1970 report supports this contention.

Spawning migration "In the Northern Hemisphere the coho or silver salmon spawns between the months of September and March, but the major runs are usually from November through January. In New Zealand, with the seasons reversed, the spawning peak could be from the month of May through July with some early and late spawning before and after these dates. This is about the same time as quinnat salmon spawn although it is customary for coho to spawn at a later date than quinnat, There is a possibility that the two salmon would be competitive on the spawning grounds. This being so the coho could disrupt the quinnat redd and cause a mortality of ova.

“The normal occurrence in their native habitat is for the quinnat salmon to enter larger rivers and spawn in the head waters, while the coho usually runs upstream a short distance and uses small shallow coastal streams almost exclusively for spawning. Normally then it is possible for these two fish to inhabit the same river system without creating a detrimental affect on either population. In conditions existing within this country where all fish spawn relatively close to the sea this might not be the case.”

Management implications “As a resource of considerable recreation value, all possible means to enhance the salmon runs should be considered. The results from the 1969-70 run, and the effects of the November, 1967, flood clearly indicate a means of doing this: by establishing artificial, but as near natural, flood-controlled, rearing channels. The size of salmon runs in the main South Island river's can be increased. The information so far obtained at Glenariffe gives no indication that the marine portion of the salmon’s existence is the limiting part. The normal flooding pattern of New Zealand rivers underlines the need to have regard for the spawning waters and their stability if we are to maintain or improve our salmon runs. The findings from the Glenariffe trap, especially thos- relating to the 1967 snow and subsequent flooding have provided us with a clear

insight into ways and means of managing this sport’s fisheries.” This stems from work done at the Glenariffe salmon trap which was put there for the specific purpose of providing management advice to Acclimatisation Societies. Add a few thousand dollars a year to put this advice into practice for the long-suffering salmon-angler who provides most of the revenue anyway, and we can have what I have tried to get for years. New Zealand’s greatest sport fishery, better than Taupo, Rotorua and the rest put together. Leave the Coho in North America where it cannot interfere with our limited spawning accommodation. Commercial interests It is this proven weakness in our fishery that prompted my letter to the editor on March 20. The North Canterbury Acclimatisation Society’s reply reveals the astonishing fact that it is unaware of the influence Dr F. B. Slack, of Victoria University, is bringing on the commercial interests of this country to introduce two further species of Pacific salmon to our rivers, which sportsmen on evidence, rightly and successfully fought to keep for sportflsn only. This information can be found in the October issue of “Commercial Fishing.” I want to make it clear to anglers and others interested that the salmon-sport fishery is in the gravest danger it has known. It faces further water abstraction in most rivers, with consequent weirs and dams and pollution. The greatest threats are the suggested new introductions, especially the Pinks and Chums, put forward by Dr Slack. All these factors can only add to our basic problem—the shortage of suitable spawning waters. How these three species of salmon would behave in our rivers in anyone’s guess. They could conceivably, destroy what we now have: the nucleus of a tremendous fishery, if managed soundly and based on scientific facts collected from the Glenariffe trap and other sources. That commercial interests will say we can make millions of dollars for New Zealand cannot be allowed to ; cloud the issue. Our fishery, i even in its present state, is already worth millions for recreation and sport. Proi perly managed it will also i earn overseas dollars. To the ■ thousands who enjoy this ■ fine sport of salmon fishing i I say: fight to keep it this i way. If you sometimes think ’ it hard to catch a salmon ’ that occasionally takes a ; bait, try catching Pinks and ■ Chums that never do.