1144 REPORT OF COMMISSIONER OF FISH AND FISHERIES. [6] 



fishes have been statlied, and their relations to water temperatures. 

 The embryological history of a number of species, such as the cod, shad, 

 alewife, sahnon, smelt, Spanish mackerel, strii»ed bass, white perch, the 

 silver gars, the clam, and the oyster have been obtained under the au- 

 spices of the Commission. 



Many other })roblems have been worked out by specialists for the 

 Commission, the details of which are described in the reports. One of 

 these, for instance, has been the determination of the cause of the red- 

 dening' of salt codfish, so injurious to commerce. Professor Farlow found 

 this to be due to the i)resence of a species of alga in the kind of salt 

 in common use, and gave instructions by which the plague has been 

 greatly lessened. 



An investigation iuto the chemical composition and nutritive value of 

 fish as compared with other food is still in progress, and all American 

 food-fishes are being analyzed by Professor Atwater. 



The temperature of the water, in its relation to the movements of fish, 

 lias from the first received special attention. Observations are made 

 regularly during the summer work, and at the various hatching stations. 

 At the instance of the Conunissioner, an extensive series of observa- 

 tions has for several years been made under the direction of the Chief 

 Signal Ofiicer of the Army and with the hearty co-operation of the Light- 

 House Board at light-houses, light-ships, life-saving and signal stations, 

 carefully chosen, along the whole coast. A number of fishing schooners 

 and steamers have kept similar records. One i)ractical resultof the study 

 of these observations has been the demonstration of the cause of the 

 failure of the menliaden fisheries on the coast of Maine in 1870 — a failure 

 on account of which nearly two thousand persons were thrown out of em- 

 ployment ; and a similar course of study recently developed by Colonel 

 McDonald seems to exjdain the recent fluctuations in the shad fishery. 



A most renmrkable series of contributions has been received from 

 the fishermen of Cape Ann. When the Fish Commission had its head- 

 quarters at Glou(^ester, in 1878, a general interest in the zoological work 

 sprang up among the crews of the fishing vessels, and since that time 

 they have been vicing with each other in eiibrts to find new animals. 

 Their activity has been stimulated by the publication of lists of their 

 donations in the local papers; and the number of separate lots of speci- 

 mens received, to the present time, exceeds eight hundred. Many of 

 these lots are large, consisting of collecting-tanks full of alcoholic spec- 

 imens. At least thirty fishing vessels were carrying collecting-tanks 

 on every trip, until it became necessary to recall them because no more 

 specimens were required, and many of the fishermen, with character- 

 istic superstition, had the idea that it insured good luck to have a tank 

 on board, and would not go to sea without one. The number of 

 specimens acquired in this manner is at least 50,000 or G0,000, most of 

 ihem belonging to species unattainable by other means. 



The success of the? incidental efforts of these men would seem to in4J- 



