FISH RESEARCH

Timaru Herald, Volume CXXXVII, Issue 19598, 19 September 1933, Page 11

FISH RESEARCH

CONDITION OF OPIHI INSPECTOR’S REPORT A recommendation that a local research committee be appointed to observe and record the movements of the fish in the Opihi river in the early spring after spawning, is contained in the report of Professor E. Percival, Honorary Director of the New Zealand Freshwater Research Committee to the South Canterbury Acclimatisation Society. The suggestion is the outcome of a visit of inspection made in August at the request of the Society, in an effort to investigate an alleged unusual state of the fishing in the lower part of the Opihi. After an exhaustive description of the Opihi and its tributaries, and their ability to produce food for fish, the report continues:— The river was low for a long period back into the winter of 1932, and the mouth was shallow or non-existent for some time, although artificial means opened up a channel from time to time, many anglers were disappointed with the fish taken, particularly about Kerrytown. Some anglers consistently were satisfied, especially those fishing off the mouths of the laterals. The poor condition was apparently restricted to mature fish, the small ones being normal. Bulleys were plentiful and fishing above Pleasant Point was satisfactory. A Working Hypothesis. While an attempt to produce a theory to explain the conditions would be unwise owing to the absence of anything like exact information either relating to the fish or to the conditions, certain features in the evidence demand consideration. There was apparently no lack of feed since bulleys were abundant, and, no doubt, there was plenty of food for them. Bulleys and trout feed on the same kinds of material. The general consensus of opinion was that the condition of fish was better above Pleasant Point than below. The smaller fish were in satisfactory condition. The following is offered as a working hypothesis and must be taken as such, to be discarded immediately if it is found not to work, viz., that the fish in poor condition were spawners which would normally have gone to sea, either for the first time or after having come in to spawn; that the very low condition of the rvier had not given them the requisite stimulus to go out, and that they were waiting for one; that such fish do not begin properly to feed (although they will take a lure) until they have got into salt water. The hypothesis demands that the general movement of fish in the lower twenty or thirty miles should be interfered with by the prevailing conditions, by the prevention of spawners or downward migrants from taking their proper places in the lower reaches owing to the presence of those which ought to have gone to sea. A Similar Experience. The conditions are reminiscent of the state of affairs prevailing in the lower Selwyn river at the beginning of the season 1932-33, where the river and lake were very low for a long period in the winter and spring. Very many spent fish had not recovered condition and did not unto a suitable amount of water came down to stimulate their movement into Lake Elelsmere. Unfortunately no records are to hand as to whether these poorly conditioned fish had fed or not and the local view was that they had becocme starved owing to their having eaten the river out. The whole question as to what happens in the early spring after spawning needs investigation, and its solution can be considerably assisted by study at the time when things are going wrong. For this reason it is very much to be desired that the South Canterbury Society appoint a sub-com-mittee of interested men who will make careful records throughout the year of the progress of events, and who will undertake the rather thankless task of collecting information from other anglers. It is necessary that information collected should be exact and should be expressed as far as possible in figures.