The Tasmanian Trout Fishery. I. Sources of Information and Treatment of Data

Abstract

This paper is a general introduction to a series dealing with the state of the trout fishery in Tasmania. Methods of collecting and analysing information are described, and the general scope of the survey is outlined.

The examination of a large number of scales in relation to the length of fish has shown that scales normally appear when the fish are about 3.6 cm in length. They grow rapidly at first and quickly establish a straight-line relationship between fish length and scale length.

Tagging tests carried out on small fish have shown that a large proportion of fish under 14 cm are unable to carry jaw-tags for more than 2 months. This is related to the relative weight of fish and tag in water, when the fish weight is reduced to about one-twentieth of its weight in air, and the tag is thus heavier than the fish.

Experimental work on selective breeding failed to yield significant results, probably owing to nutritional deficiencies associated with hatchery rearing.

The growth of individual brown and rainbow trout in relation to temperature was followed for about 3 years.