566 



therefore the weight, of the marketed catch. Some correspond- 

 ence in plankton and the products of the fisheries might there- 

 fore be expected, though on account of the complexity of the 

 problem and the limitations of our data it is difficult to demon- 

 strate it in every case. 



In 1894, when our data indicate a plankton produotion be- 

 low the average in channel, in backwaters, in their sum, and in 

 the estimated discharge, we find the total production of mar- 

 ketable fish also below the average (for 1894-1898). In 1895 

 our collections indicate an increase, approximating 50 per cent. 

 in plankton production as exhibited by each of the methods 

 tabulated, and there is also an increase in the product of the 

 fisheries, though it amounts to only about 4 per cent. The 

 direction of the change in production is the same in all cases. In 

 1896 plankton production falls in channel, in backwaters, in 

 their sum, and in total discharge, the decline in all but the back- 

 waters being greater than the increase from 1894 to 1895, and 

 we find, accordingly, that the decline in the product of the fish- 

 eries is also greater than its antecedent rise to the level attain- 

 ed in 1895. In 1897 plankton production again rises in the 

 channel, in the sum of channel and backwaters, and in total 

 discharge, but not in the backwaters. This apparent decline in 

 backwater production may be due to the elimination from our 

 data, for a part of the year, of Phelps, Flag, and Dogfish lakes, 

 thus giving undue weight to the depressing effect of the Quiver 

 Lake data. The fact that in Thompson's Lake plankton pro- 

 duction rises from 6.67 in 1896 to 10.41 in 18971s an indication 

 that plankton production in the open backwaters in 1897 rose 

 above the level of that of 1896. In correspondence with the 

 increased plankton production in channel, and total discharge, 

 we find the product of the fisheries rising from 7,252,811 pounds 

 in 1896 to 9,703,298 in 1897 — a change not exceeded in any 

 other year of the records. In 1898 the product of the fisheries 

 continues to increase, reaching 10,647,466 pounds, but plankton 

 production rises only in the backwaters and in the sum of chan- 

 nel and backwaters, falling in channel and total discharge. 



