SERVICE FOR TROUT

Bay of Plenty Beacon, Volume 1, Issue 56, 30 August 1939, Page 7

SERVICE FOR TROUT

BLACK SHAGS PREY ON EELS A correspondent of the Gtago Daily Times commends the action of the Southland Acclimatisation Societj*- i n waging war on eels in trout streams, and chides the Otago Society for not following that example. "If the Otago Society," the writer remarks, "had killed as many eels as the Southland Society killed last season it would have saved feed enough for 77,000 trout of lib each.. This would have been about 30 fisn each for the Otago license 'holders. We cannot carry a large head of ecus and trout to any given area of water any more than we can carry sheep and rabbits on the land without either sheep or rabbits decreasing.' It is well known that the muchpersecuted black shag is very fond of eels, which form an important part of its ordinary diet. The clever technique of the captor is thus described by Mr Edgar F. Stead in his book "The Life Histories of New Zealand Birds." ''The catching of a good-sized cl! by a shag is quite an interesting performance to -watch. The bird dives, and presently comes up, and in its bill is an eel, say tw? feet long, wriggling and squirming as onty an eel can; yet the shag is able to hold it without difficulty, for the eklges of its bill are so shar.p that they cut into the eel's skin and so give a good grip. After waiting a moment or two for the eel to get over its first paroxysms, the bird shifts its grip to get its prey by thel head. The eel is by no means idle, and tries to hook its tail around the bind s neck and so get a leverage that will unable it to twist itself out of the bird's bill. The shag's counter move is to throw its head forward and down, but often the fish succeeds in getting such a grip that the bird is forced to let it go, in order to get free of its coils. The eel disappears under water, but the biid instantly follows, and in a few seconds comes up again with it, and the contest begins afresh. On an average such an eel will break away three or four times but if the water is not weedy the shag recaptures il without difficulty, and gradually th 1 struggles of the fish become less and less violent/' This matter of eels in relation to trout—especially in districts where black shags, the natural enemies of eels, have been nearly exterminated —is another reminder of the need ot the long-deferred accurate survey of wild life. Ignorance is the cause of many blunders in the upsetting of nature's methods of maintaining a /balance.