AGE OF FISH-SCALES

Hokitika Guardian, 28 May 1932, Page 6

AGE OF FISH-SCALES

EXAMINATION BY PROFESSOR

NEW ZEALAND CAMPAIGN

(By Telegraph —I'er Brest Association)

WELLINGTON- May 26

Valuable voluntary work on behalf of various acclimatisation societies is being done by anglers throughout New Zealand. They are sending hsh scales to Professor Percival, of Christchurch.

About three years ago co-operative fresh-water fish research was established by the societies, Professor Percival being elected honorary director. The object is to determine the growth of fish in relation to their age and thus to find the best methods of keeping up and improving the stock in New Zealand rivers.

Importance is lent to the campaign because, in the opinion of experts, existing river fish are deteriorating, in quality either from overstocking or lack of food. It has been pointed out that the enormous fish caught in past years—fish which helped to gain for New Zealand her reputation as an angler’s paradise—were all progeny of the first importations in the days of sailing ships. These river giants thrived on the food that was present in such abundance, but their progeny are now reverting to type. Thus. far the evidence shows' that there is still plenty of food available, but the investigations are being continued in the hope of solving the problem of the changing types and restocking the rivers with specimens equal to those of the past'.

By examinng the scales of fish of known weight and dimensions, Professor Percival is able to compile valuable data relating to the development of fry liberated in various rivers. Under a microscope the scales are seen to have little circles which multiply at the seasons pass. Thus the age of ’a particular specimen may be determined by “reading” , the scales, much as the age of a tree may be calculated by counting the rings on a cross-section.