COD-FISHEEIES OF CAPE ANN. 727 



them oil its way to the reservoirs. During stormy weather, when tho 

 bottom mud was stirred up, the water was often i)a.ssed through six or 

 seven of these filters, but even then the finer sediment could not be kept 

 back. Frequently the dirt was pumped up in such quantities as to so 

 completely clog the filters that the water would not go through them, 

 and at such times they had to be replavced ])y clean ones every few min- 

 utes during the hours of low water. Other methods of filtering were 

 also tried with no better success. 



The new Fish Commission steamer, built expressly for this work from 

 a special appropriation of Congress, will entirely do away with this diffi- 

 culty resulting from impure water, as she can be safely anchored in the 

 deep water of the outer harbor where no sediment is found. 



The corroding action of the salt-water upon the copper and tin of 

 which the apparatus was made, was also the source of considerable 

 trouble. The copper cones were rendered useless on this account, and 

 tin was often eaten entirely through in a few days. This difficulty was 

 partially overcome by thoroughly painting the cones with asphalt, but 

 even then the tin would rust so badly as to seriously injure the eggs. 

 All trouble from this source can be easily avoided in future by making 

 the apparatus of wood or some metal that is not acted ujion by the salt- 

 water. Indeed, nickel wire-cloth was used during the latter part of the 

 season for the bottoms of the buckets, and found to answer the purpose 

 admirably. 



The fact that the cod cannot live in water colder than 30"^ F. presents 

 another difficulty, for it is of the utmost importance that a large supply 

 of fish be kept constantly in the live-boxes ; and, as the water at the 

 surface of the harbor may reach this temperature at any time for several 

 months during mid -whiter, the fish are liable to be frozen. But with a 

 steamer anchored in several fathoms of water in the outer harbor, the 

 live-cars by her side could, at the approach of cold weather, be weighted 

 and sunk to the bottom until the weather should become warmer. 



G. — EXPERI3IENTS WITH EGGS OF OTHER SPECIES. 



While the primary object of the station at Gloucester was for the 

 study of the cod, the question of the reproduction of several other im- 

 portant species received considerable attention, and much valuable 

 information was gathered. Among these species were the haddock 

 {Melanogrammus ceglefijius)^ the pollock {Pollaehins carhonarius), and the 

 herring {Chipea harcngits). 



a. Herring. 



Herring visit difierent parts of the coast from Cape Cod to Labi^ador 

 at various seasons of the year for the purjiose of spawning or feeding, 

 and are abundant in some localities during a greater x)art of the summer. 



In the winter the herring-fisheries of Newfoundland and Xova Scotia 

 are very extensive ; and formerly the spring herring-fisheries of the 



