SHAGS AND TROUT

Press, Volume LXI, Issue 18310, 18 February 1925, Page 12

SHAGS AND TROUT

(By Edgar F. Stead.)

THE CASE FOR THE SHAG.

In the winter of 1919 a great many shags were roosting on the Rakaia riverbed. With Mr M. H. Godby I went, down on June 17th to shoot some of them for investigation. On our way down at midday we saw a shag fishing in the Selwyn at Ellesmere.' It fished tip a pool a hundred yards long, and then we shot it. I examined "the pool, and saw numbers of small trout in it, but the shag had succeeded in catching only one. At the Rakaia we got twelve shags, and on August 15th of the same year, with Mr C. E. Clark, I shot four more there, making a total of sixteen. Of these sixteen shags two had their food so digested that we could not identify it: the other fourteen contained a total of 2 trout, 20 eels, 8 small herrings (one bird), some remnants of flounders (one bird) and silveries One bird had the two'trout as'well as two eels, and of the sixteen birds, thirteen contained eels, the largest of which were eighteen inches long. On January Cth, 1920, Mr L. A. Shand and I watched a shag fishing a small branch of the Ashley. When it left off, and flew past us we s'net it, and found it to contain a large whitebait and an eel. Xear Lake Ellesmere I have frequently shot shags and never found anything but eels in them. At the mouth of the YVaiinakariri last Friday I was fishing with three other anglers, when a shag flew down and began to fish nearby. One of the other anglers said to me: "There is one of vour friends. Do you think it is after eels?" I replied, "Yes," and, sure enough, within a few minutes up came, the bird with .an eel about lift long. _ . 1 could give many more instances, but think the above sufficient support for my contention that a shag "will always take eels, if it can get them, in preference to trout. If not, why should the majority of: the shags, which were the Kakaia, go all the way to Lake Ellesmere (as "I do not doubt they were doing) for eels, when they could have caught trout in the river at their feet? Why do most of the shags, which roost up the Waimakariii not fish there if they prefer small trout, instead of going down to the tidal waters? During the "run" of "bait" (silveries) in our bitf rivers, shags come to feed on it, and also, as I have seen, oil the eels which follow the "bait." •

lii 1907 the North Canterbury Acclimatisation Society ceased to pay for shags' heads in its district. The locality that has been most affected by this policy is Lake, Ellesmere, where the shags have greatly increased in numbers and now frequent the mouths of the Selwyn and No. 2 rivers much more than tliey did when they were shot. The intervening period has been marked by a notable increase, both in the size and' in the numbers oT the trout taken in these rivers. This result I consider to be largely due to the removal by shags of large quantities of eels from the lake. The shags from Lake, Ellesmere, which I have shot and examined have contained an average of over one eel per bird, and I think that at the present time there are certainly not less than three thousand shags fishing there. Taking their catch at only one eel per bird per day, we get a total of well over a million eels per year! Now, a million eels would eat a lot of food, and if the eels ate removed so much more food is. available for. the trout. ' Evidence that eels will increase if the shags are destroyed is not wanting. The president of the Otago Acclimati-. sation Society told., me that lie had been informed that in a river in their district eels had greatly increased of late years, since the shags, which were once numerous on it, had been shot. In its native habitat (Europe), the trout has many natural enemies, and its "high fecundity was evolved to meet a high death-rate. Among its* enemies were several mammals, the worst of which was the other; many birds, including some (e.g. the golden-eye duck), which do great damage by eating spawn; and a number of fish,, among which may be mentioned perch, 'tench, eels and. pike, which, one or another attacked it at all stages from the spawn up to fish weighing several pounds. Here in New Zealand it had only two natural enemies of any consequence whatever, the eel and the shag. Now, it is absolutely essential that there, he some natural, means for reducing the numbers of trout in our streams. '.•., If it were possible to remove their natural enemies, altogether, then the trmit would soon become so numerous that they would eat out all their food sirpv ply, and migrate to other waters:, or die of starvation.;-'

There are. many streams in Canterbury where the trout have practically eaten out their food supply. The headwaters of 'the Selwyn may be taken as a typical iustance. Thirty, years ago there was magnificent angling, to be obtained from Coalgate to Highpenk. Then the trout increased in numbers until the stream becamei over-stocked, and the size of the fish fell as a consequence. Ten years ago there were thousands of trout in the river of about nine inches long, and they were old fish —fish of three and four yearsshowing that their food supply was not sufficient to produce rapid growth. More recently they have almost'completely 'forsaken- the headwaters of the river and the small streams which run into it. I do not think that this great reI iluction in the numbers of the small trout at the head of the Selwyn can l)e attributed to anything else than, shortage of food. ■ In the vicinity of (rlentunnel I know that the case is somewhat complicated by persistent poaching, ■ but that does "not apply abpve the gorge. About twelve years n'.go the Acclimatisation Satiety, received a complaint that shag were clearing the trofit out of the Selwyn .at Glentunnel. Together with another member of the council, I went' up there to investigate. Wo interviewed the man who had nwde the complaint, and he admitted that, there were hundreds of small fish in the pools, but said there were no big ones, and put this down to the shags. I pointed out to him that it was unlikely that shags would take trout of over si pound if there were plenty of small ones about, «nd with this he azreed, but still he did not like the idea of the shags getting any trout at all. That is quite typical of the attitude of most anglers towards the- shag. Even men who are successful "farmers do not seem to realise that overstocking is just as bad in the water as on the land, and that it is quite as necessary to thin out our fish selectively as it is to cull our flocks. Angling is> not nn effective means of culling fish, as both the fit and the tinfit are caught.

There is no country in- the %-orld where the study of birds ecologically ;md from an economic standpoint has been carried out so we'll as in the United States of America, and thero they not only protect shags, hut pUice g;:iiie wardens near the larger nesting colonies to ensure that the birds are not disturbed. One of your correspondents on this subject. Mr Sealer. has evidently •riven this matter a good .deal of attention, but, as I have si:>id above. 1 do not think the shag should be condemned because it takes trout. In

189",.-when I fished the Ashburton River at Vesterfield, trout were very plentiful and averaged between three and four pounds in weight, the smallest being; 21b and the biggest over 61b. I realise now, though I did not then, that the river was overstocked, and was surprised, a few years later, when I learned that the fish had much deteriorated. In Lake Alexandria there has been a plentiful supply of big trout for angling (the fish are not - free j '(takers," I admitXand it .seems to me. i tha,t a supply, of shags there to.keep [the numbers of the fish within limits is wholly to be desired.. The shooting i of the shn.gs on Lake Taupo I have always regarded as very ill-advised, I .for the whole history of the aeolimati- ! sation of rainbwv trout •in . the Hot I Lakes district shows that the great L difficulty is hot in stocking the waters with this trout but in preventing overstocking. Mr Sealey says that most [anglers'do not share my views'.on .the shag, but this I do not regard as a serious criticism of them, for I think.l am doing anglers no injustice: when I say [.that the Vast majority of them have I: never -given the matter T.ny serious thought. They see a shag take a [trout, therefore the shag should be shot, for if it ..had. not got the fish, thev might have done so. The black shag desenves some consideration for yet another reason. It is 'the largest of our native birds which Iv'tfill,become very tame if not molested. In Canterbury it has already returned to the cliffs at Sumner,'and nests on the ledges of rock, undisturbed by the' motor-lorries and electric trams which rush past on. the main road tnidernenth.' If the birds are left alone there, they will , soon re-establish- <t nesting colony on Shag Rdtek, and provide a source of endless interest for all who care to watch them. The more the public sees and becomes interested in Any birds the easier is going to be the work of the Acclimatisation Societies' in .protecting .birds generally. (Concluded.)