208 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 



tlie southeasterly coast of Kamchatka, where an immense area over 200 

 miles in width at its eastern extremity remains unexplored. 



Character of bottom. — Black sand and gravel occur on Baird and 

 Slime banks, in Bristol Bay ; also in Unimak Pass and off' the north 

 shore of Unalaska Island. Spots of black and gray sand occur north 

 of the Pribilofs, but a large proportion of the vast area within the 

 100-fa thorn curve is dominated by green mud, having usually a propor- 

 tion of fine sand, although this is not invariably the case. 



In the deeper waters, even to depths exceeding 2,000 fathoms, green 

 mud occupies a prominent place, with a small percentage of fine, gray 

 sand, which during the season of 1890 we mistook for foraminifera. 

 Clay occurred once only in Bering Sea, in latitude 55° 38' JST., longitude 

 170° 39' W., at 1,171 fathoms. Bocky bottom was found occasionally 

 near the 100-fathom line west of the Pribilofs. 



Water Temperatures. — The surface temperature of the Pacific Ocean, 

 south of the Aleutian Islands, during July and August, was from 48° 

 to 50° P., while in Unimak and Amukta passes it was but 40°. Marked 

 variations of temperatures have been noted in Bering Sea and com- 

 mented upon by navigators, some of whom have ascribed the phenome- 

 non to mysterious agencies. It can readily be accounted for, however, 

 from natural causes. Inside of the 100-fathom line the surface tem- 

 peratures were from 44° to 46°, while at the bottom they ranged from 

 35° to 40°, and between IsTunivak and St. Matthew were as low as 31°. 

 The temperatures at the surface fell with shoaling water, approxi- 

 mating to that of the bottom as the depths decreased, until in some 

 instances both were the same. A fall of 3° to 4° was noted in 

 approaching the Pribilof Islands. 



Outside of the 100-fathom curve, and particularly between the seal 

 islands and Amukta Pass, the surface temperature was about 47°, or 4° 

 higher than inside of the curve and 3° lower than the Pacific outside 

 of the pass. This condition is owing to natural causes also, as the 

 weight of current is from the warmer waters of the Pacific through the 

 archipelago into the colder region of Bering Sea. 



The mean surface temperature in the harbor of Unalaska during 

 July, August, and the first week of September was 50°. 



Serial temperatures observed showed frequent mingling of warmer 

 and colder waters. 



Currents. — Regular tides were found inside of the 100-fathom curve, 

 the flood strongest and setting to the northward, the ebb running in 

 the opposite direction. They were greatly affected by winds and the 

 proximity of land, and around the Pribilof group they were particularly 

 strong and erratic. Outside of the 100-fathom curve there was a general 

 northerly set, light, however, and greatly affected by prevailing winds. 



Intermediate tow-net. — This apparatus was used frequently with good 

 results between 25 and 250 fathoms. 



Codfish. — The only known cod fishing- grounds of commercial value 

 in Bering Sea are Baird and Slime banks, in Bristol Bay. They are 



