182 American Fisheries Society. 



from surface to bottom. Those members of the American Fisheries 

 Society who are familiar with limnological work, and with the ex- 

 tremely short periods during the spring and fall, when such con- 

 ditions are found, can understand the length of time required to 

 carry out these tests. In each experiment the apparatus an3 

 methods of procedure were the same. A wire cage containing the 

 fish was attached to a measuring line and lowered 6 inches at in- 

 tervals of one minute each. At every 5-foot mark the cage was 

 raised, at the same degree of speed, to the surface for observation. 



No. 1. April 12, 1914. — Six landlocked salmon, advanced-fry (feeding 

 two weeks) returned from 5-foot depth in uneasy condition; from 10 feet, 

 all dead. 



No. 2. April 12, 1914. — Six 10-months-old steelhead; 5 feet, no change; 

 10 feet, all distressed, three had changed to pale color ; 15 feet, five dead 

 with one in very feeble condition, which upon being returned to hatchery 

 died later. 



No. 3. April 13, 1914. — Four yearling salmon and four 22-months-old 

 steelhead ; 5 feet, no change ; 10 feet, all salmon changed color ; 15 feet, 

 one salmon dead, others distressed ; 20 feet, all salmon and one steelhead 

 Head ; remaining steelheads lowered to 55 feet with no bad effects except 

 slight change in color. None of these steelheads died later in the hatchery. 



No. 6, November 10, 1015. — Four 19-months-old salmon and four finger- 

 ling steelheads; 5 feet, no change; 10 feet, two steelheads dead, all uneasy; 

 15 feet, other steelheads dead ; 20 feet, two salmon distressed, others normal ; 

 25 feet, one salmon dead; from 30-foot depth to 55 feet, no change, and 

 two salmon in normal condition and one distressed were returned to hatch- 

 ery. None died later. 



No. 12. November 14, 1915. — Six fingerling salmon, all died between 

 the 10 and 15-foot depths. 



No. 21. March 27, 1916. — One 2-year-old salmon with smolt coloration 

 and one 20-months-old steelhead with partial smolt development were lowered 

 to 60 feet without visible ill effects. 



No. 24. April 3, 1917. — Two precociously-developed yearling salmon of 

 6 and &% inches, with indications of abnormally early smolt development, 

 were killed between the 20 and 25-foot depths. 



No. 25. April 4, 1917. — Two 2-year-old salmon, which still retained the 

 parr markings, although the spots had faded to a faint orange. One died 

 at 40 feet, the other remained normal. 



No. 29. April 11, 1921. — At Sterling Lake, N. Y., two 2-year-old salmon 

 and two steelheads 22-months-old, as fully developed smolts, were lowered 

 to a depth of 110 feet without ill effect Or noticeable change in color. 



The above tests were taken from a list of fifty-four, which 

 were brought to a conclusion in November, 1921. Many of them 

 were in duplicate and were made in order to confirm former re- 

 sults and for the purpose of post-mortuary examination with micro- 



