THE THAMES A SALMON RIVER.
MR. ALGERNON BOURKE, in a letter to the Times of Monday, suggests that an experiment should be made to discover whether the Thames is yet fit for salmon to live in. He would turn out a number of two-year-old smolt into the upper waters, or hatch fry on one of the tributaries, and then wait for their return as "grilse." The reappearance of even one or two of the latter would show that the river is once more " open," and encourage experiments on a larger scale. Evidence has been accumulating recently that there is some chance for the salmon. The improvement of the water of the "London River" has been marked by a steady increase of fish, and a return of species which have deserted it for half a century, to a degree considerably beyond the estimate made by Mr. Algernon Bourke in his letter. The return of the fish has been going on steadily since 1892; and their advance has covered a distance of some twenty miles,—from Gravesend to Teddington. The first evidence was the reappearance of whitebait, small crabs, and jelly- fish at Gravesend in 1892. In 1893 the whitebait fishermen and shrimp-boats were busy ten miles higher than they had been seen at work for many years. The condenser tubes of torpedo-boats running their trials down the river were found to be choked with " bait," and buckets of the fish were shown at the offices of the London County Council in Spring Gardens. It was claimed that this evidence of the increased purity of the water was mainly due to the efforts of the Main Drainage Committee of the London County Council. There is abundant evidence that this claim was correct, for instead of allowing the whole of the London sewage to fall into the Thames at Barking and Crossness, the County Council used a process to separate all the solid matter, and carried it out to sea. The results of the first year's efforts were that over two million tons were shipped beyond the Nore, ten thousand tons of floating refuse were cleared away, and the liquid effluent was largely purified. It was predicted at the time that if this process were continued on the same scale it would not be long before the commoner estuary fishes appeared above London Bridge, even if the migratory salmon and sea-trout still held aloof. Unfortunately there has been some deviation from the methods of dealing with the sewage, a change from which we believe that some of the officials concerned with the early improvements very strongly dissented, that has to some extent retarded the advance of the fish. But during the past two years a sudden "spurt" has taken place in their return. Whitebait became so plentiful that during the whole of last winter, and the spring of the present year, the results were obvious, not only to naturalists, but on the London market. Whitebait shoals swarmed in the Lower Thames and the Medway, and became a cheap luxury even in February and March. They were even so suicidally reckless as to appear off Greenwich. Supplies of fresh fish came into the market twice daily, and were sold retail at sixpence perquart. Last spring the Thames flounders once more reappeared off their old haunt at the head of the Bishop of London's fishery near Chiswick Eyot. Only one good, catch was made; but this had not been done for twelve years, and there is a prospect of their increase, for, in the words of old Robert Binnell, Water Bailiff of the City of London in 1757, we may "venture to affirm that there is no river in all Europe that is a better nourisher of its fish, and a more speedy breeder, particularly of the flounder, than is the Thames." Eels were also taken in considerable numbers between Hammersmith and Kew; but the main supply of London eels came from Holland even in the days of London- salmon. In a very old print of the City, with traitors' heads• by the dozen on London Bridge, "Bale Schippes," exactly like the Dutch boats lying at this moment off Billingsgate, are shown anchored in the river. Besides the estuary fish which naturally come up river, dace and roach began to come down into the tideway, and during the whole summer the lively little bleak swarmed round Chiswick Eyot. Later in I the year the roach and dace were seen off Westminster, and
last week several were caught below London Bridge. But August and September marked the highest testimony yet paid by the salt-water fishes to the purity of the river. In August the delicate smelts suddenly reappeared at Putney, where they had not been seen for many years. Later, in September, another migration of smelts passed right up the river. Many were caught at Isleworth and Kew, and finally they penetrated to the limit of the tideway at Teddington, and _geed baskets were made at Teddington Lock.
This additional evidence of the satisfaction of the fish with the County Council does not quite satisfy us that the London liver is yet clean enough to give passage to the migratory salmon. It is encouraging to the County Council, who deserve all the credit they can get; but there is little doubt that the best evidence that the river is fit for the salmon would be the spontaneous appearance of the salmon themselves. As it is known that both salmon and sea-trout in the " grilse 31 state make their appearance nearly every year at the mouth of the Thames, ready to ascend and restock the river as soon as its poisoned waters shall be sufficiently purified as to allow them a passage, the fact that they do not make the trial seems to show that it is not yet ready. On the other hand, these trial visits of the salmon are probably half-hearted, for the fish are generally believed to reascend those rivers in which they were bred. As no salmon have bred in the Thames for nearly a century this inherited instinct must be worn out, and the fish which enter the month are only "prospectors," not re- turning emigrants. Thus there is some ground for believing that Mr. Bourke's suggested experiment might meet with success, and his grilse, grown from smolt, turned out on the upper waters, or originally hatched from ova laid in the Kennet or the Fairford Colne, with the more strongly developed instinct of return, might realise his hope, and be "seen leaping at Richmond Lock." There is no doubt that the Thames from above Teddington Lock to its source is as good water for the fish as ever it was ; and it is just possible that we overestimate the probable effects on the general well. being of salmon of the foul condition of the Thames below London. Experiments seem to show that though the change from the river to the sea is of the utmost benefit to the salmon, its stay there is very brief, and that the greater part of its life is spent in the fresh water of the rivers. Mr. Young, of Invershine, writing of the experiments con- ducted by the Duke of Athole and himself, found that the majority of the marked fish returned in about eight weeks to the rivers, after spawning, and yet that in this short time they had increased from 5 lb. to 10 lb. in weight This is an astonishing record ; but the late Duke of Athole .recorded an instance of a fish caught above Dunkeld Bridge, and marked by him, which weighed 10 lb. ; within five weeks and two days, it was caught again on its way up from the sea, when it was found to have gained lb. On the other hand, practical fishermen contend that, as a fact, the fish do not spend forty or more weeks in the rivers ; and believe that they take more than one trip to the sea in the twelve months, which would make the state of the Lower Thames a matter of more serious importance when the fish were once more established. The size and number of the steamers passing to the port of London might also prove a. possible obstacle to the return of the salmon. It was noted that when the large steamers began to call in numbers at Southampton, the salmon began to leave Southampton Water.
Next in importance to the state of the river month is the condition of the head-waters of the main stream and tributaries whither the fish ascend to spawn. Curiously enough, there remains no trace or tradition of the spawning beds anciently used by the Thames salmon. The fish need a gravelly or shingly bottom, and fast-running water. There is plenty of the former on the Upper Thames; but the tributaries are not ideal spawning grounds; the head- waters of the Thames itself in the Cotswolds would be suitable, if protected. But if we trace any of the Oxford- shire, Surrey, or Berkshire tributaries to their sources, the Cherwell, the Wey, the Loddon, the Colne, Windrusb, or Evenlode, we find no great amount of suitable spawning ground. Nearly all these streams rise among chalk hills ; many of them contain good trout on the upper waters ; but tot even the Kennet strikes ue as the place to expect to find spawning salmon. The Fairford Colne would probably suit the fish better than any. There is little doubt that the
experiment of turning out smolt or ova will be tried, and that if there is the slightest evidence that it may suoceed it will lead to further purification of the river. Public attention will be constantly drawn to its condition by the interest taken in the migrations of the salmon. All the fishing societies, which are numerous and vigilant, will be on the alert, and publish weekly reports ; and though the salmon will be the main object of attention, the simultaneous increase of other species, or their decrease when the river is neglected, will be constantly noted in the papers. Fish are the best "public analysts" in the world when a report is needed on that most difficult question, the pollution or purity of water; and even from this point of view they deserve encouragement. Moreover, they "work automatically," require no pay, and come up to the top of the water when sick, to show that matters are amiss.
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