In the smaller bodies of fresh water there is no doubt of the effectiveness of hatchery operations, but in the Great Lakes of North America there is no dependable evidence of their value.
Official statistics studied by P. Reighard in 1908 showed, on their face, a correlation between the average intensity of the plants of whitefish fry in certain regions of the Great Lakes during three five-year periods from 1892 to 1906 and the average catch of whitefish for the same periods. Intensive planting was found to be correlated with an increased fishery output and was recom mended. On the other hand Dr. Koelz, who has an intimate knowledge of the fisheries operations of the Great Lakes is doubtful of the value of statistics based largely on reports of interested parties, the fishermen. He points out further that the planted fry are a very small fraction of those presumably hatched naturally (0.35% in Lake Huron in 1900).
The decline in the coregonine fisheries of the Great Lakes is further evidence of the inadequacy of present hatchery methods.
Whether the whitefish (Coregonus clupeaformis) has declined is uncertain, but the bluefin of Lake Superior and the bloater of Lake Ontario (both forms of Leucichthys nigripinnis) have be come commercially extinct and in 1925 the important Lake Erie herring (L. artedi) suddenly gave out and has not since regained
its commercial importance. The bluefin and bloater were never propagated artificially, but hundreds of millions of Lake Erie herring eggs have been hatched annually. It appears from these three cases that, for some unknown reason, wizen the breeding stock of a gregarious fresh-water species has been reduced below a certain numerical minimum the decrease continues. In the case of the bloater it has led to extinction and the important Lake Erie herring, in spite of extensive hatchery operations, appears now to be faced with extinction. The value of artificial hatching as hitherto carried out in the Great Lakes is now questioned in the United States for the reasons stated above and in Canada the abolition of hatcheries has been advocated by Prof. Knight of the biological board of Canada. It is probable that the life his tories and migrations of many species approach in intricacy those of the Pacific salmon with its numerous, independent, self sustaining colonies or races. Until these intricacies are resolved by prolonged research and hatchery operations adjusted to them, it is felt that artificial propagation is, in most cases, carried on blindly and that success depends on chance.