RECENT RESEARCH UPON SALMON 237 
Archer. On several days in succession he asked the net- 
fishermen to lay out their catch according to sex. They did so 
without hesitation. Mr. Archer then obtained leave to make 
ajsmall incision in each fish to expose the ovary, and proved 
that the fishermen were just as often wrong as right. It is 
probable, therefore, that all but the largest male kelts speedily 
get rid of the cartilaginous growth on maxillary and mandible, 
which distinguishes the male at the time of spawning. This 
suggestion is considerably strengthened by some of the entries 
in the tables of marked fish recaptured and recorded by the 
Fishery Board for Scotland.* 
There are a number of instances such as the following :— 
No. 1,909 : An unspawned fish taken in the Spey on November 
28th, 1896, is returned as a female weighing 18 lb. The sex 
at time of capture must have been evident beyond all doubt. 
The same fish, recaptured on March 27th, 1897, is returned 
as a male kelt weighing 124 lb. Again, No. 2,032 is taken in 
the Spey on December 23rd, 1896, marked and returned as a 
male clean fish weighing 7% lb. Recaptured on February 16th, 
1897, it is returned as a female clean fish of the same weight. 
In short, out of 190 fish specified in the return to have been 
recaptured, no less than twenty-three, or about 12 per cent., 
are shown as having changed sexes in the interval. This 
‘surely ought to make one slow to found upon external 
indications of sex. 
Reference has been made above to fresh light which has 
‘been thrown upon the disputed question of the to-and-fro 
migration of salmon between the sea and fresh water, other 
than the single ascent to and descent from the spawning beds. 
Obviously this point is of much importance to the preservation 
of rivers and to any legislation which may be devised to 
prevent undue depletion of stock ; because thereon depends 
the amount of loss to which the stock is exposed during a 
single season at the hands of net-fishers. Forty years ago the 
* Report, Part II., 1902, pp. 63-72. 
