THE SPAWNING PERIOD 163 



equal compressibility at every part enables it to adapt its shape to any 

 crevice, and so it is " worked " quickly by the motion of the stream 

 into any niche that will contain it. 



It is erroneous to suppose that the male fish takes any part in the 

 formation of the redd. His active efforts are confined to protecting his 

 chosen companion from the attention of other males, and to dispersing 

 the small trout which hover near intent upon snapping up such stray 

 pellets of ova as come their way. It has been alleged that in spite of 

 his domestic anxiety there are grounds for suspicion that the male fish 

 is not averse from levying on his own account a food tax on the ova, 

 but in all fairness, I must admit that I have not myself seen him do it. 



The male sea-trout does not remain to watch the redds as the male 

 salmon is said to do, but bolts for the shelter of deeper water as soon 

 as his labours are over. 



It may occur to the reader that when trout, sea-trout and even 

 salmon are spawning in company, simultaneously and more or less 

 promiscuously (as may easily happen in some districts), a certain amount 

 of cross-breeding will inevitably take place. I do not doubt that such 

 cross-breeding does occur in nature although few hybrids can be 

 detected with any degree of certainty amongst mature fish. I think the 

 explanation probably is that, the three species being so closely inter- 

 related, the attributes of the hybrid become indistinguishable from the 

 general features of the species which most strongly predominates in the 

 cross. 



For instance, if salmon ova be fertilised by trout or sea-trout milt, 

 or trout or sea-trout ova by salmon milt, I expect — as the salmon is the 

 stronger fish — that the progeny of the cross would be so like the progeny 

 of true salmon parentage as to be indistinguishable from true salmon. 

 As for trout and sea-trout, however they may be crossed inter se, there 

 can be little doubt (even apart from Mr. Regan's theory) that the 

 progeny in any appropriate environment develop into migratory sea- 



