ATLANTIC SALMON.

Otago Daily Times, Issue 20320, 31 January 1928, Page 7

ATLANTIC SALMON.

EXPERT’S VIEWS,

(From Our Oivn Correspondent.) GORE, January 30.

The Chief Inspector of Fisheries has written to Mr R. Fisher, of Gore, giving the under-mentioned tentative readings regarding the scales from the Atautic salmon caught at the mouth of the Waiau River on December 28. The inspector points out that European salmon scales can be read with a certain amount of certainty, but New Zealand specimens are not so easy to understand. Nevertheless, the New Zealand salmon scales in question show zones of differing character. and when a sufficient number of specimens representing salmon is as many stages as possible is avai’able fhr study it will be possible to throw a good deal of light on the life history of our fish. At the present stage the standards of reference are not properly settled.

(1) Female 91b, length 29in, girth 14in; caught by Mr R. M'Kenzic, Invercargill, Waiau Month, near the breakers, December 28. 1927. Stomach contained small sea crabs. No spawn.

(2) Female, weight 7-lib, length 30in, girth 13in; caught by Mr R. Fisher, Gore, near the mouth of the Waiau, December 28, 1Q27. Full fresh spawn, Stomach empty.

Scale Reading.— (1) The fislt lived through a period containing apparently two winters (but it might possibly be only one) before reaching a stage characterised by appreciably increased growth. Steady growth was then maintained with no indication of cheek or slowing down till the fish reached a size of about six times the length at which it finished its par existence. Then there occurs a very definite diminution of growth rate. After this is shown a distinct break or check. This I think, represents a spawning mark, though not so distinct as is shown in European salmon. After this break, which presumably represents its spawning season, it grew slowly for a time. This probably, represents the post-kelt stage, when the fish fed to some extent, probably in fresh water. After this it grew more rapidly up to the time of its capture. In this specimen it is very difficult to correlate the growth zones with definite seasons of the year. The following may be given as its probable iife history;—Two years (possibly only one) as a parr, followed by one year of very rapid growth, after which if spawned. It probably migrated to the sea (whether for the first or second time cannot be ascertained with certainty) in the spring of 1927, and the last phase of scale growth probably represents the period from then till its capture in midsummer.

(2) This fish showed scale characters very similar to those of No. 1, and most probably it belonged to the same generation or year-group. There is a faint indication of two slight checks in the growth of the parr which may represent winters. No well-marked transition is shown between the early slow-growing stage (parr to smelt), and the phase of rapid growth (when the adolescent fish is growing into a salmon). There is a period of good steady growth before a slackening takes place immediately prior to the definite check which apparently indicates the occurrence of spawning. This apparent spawning mark is not shown equally well in all scales, especially in the interior part of the scale. This fish shows more growth after the spawning mark than is the case with No. 1.

Except for the slight difference mentioned above, the ago and life conditions of this fish were almost certainly the same as in the case of No. 1.