4 THE AMERICAN MIDLAND NATURALIST 
pletion of the mussels resources, and the consequent decline 
of the clamming industry may be given: 
1. The smothering of the mussel beds by sand deflected 
by the dams ‘has been previously indicated. Additionally it 
may be stated that the increased current thereby insured has 
the probable effect of sweeping juveniles just dropped from 
fish long distances down stream, or to lodge them upon the 
sand bars, where later they may be covered up. 
Within the limitations of the apparatus used in this inves-. 
tigation, it was not found practicable to estimate quantitatively 
the extent of the mussel beds smothered in this fashion. 
Under such circumstances, the dead shells were difficult to 
collect by the prevalent method of clamming. To indicate 
that such beds were formerly extensive are the statements 
of fishermen as corroborated by the observation of govern- 
ment engineers. Mention is made further on of those beds 
which came under the party’s observation. 
2. Destructive fishing methods formerly in use, such as 
taking very young shells, deliberately clamming out beds, or 
fishing with the shoulder rake, are also responsible. The 
party found evidence of the latter in most of the beds last 
mentioned. However, favorable sentiment toward respecting 
this part of the protective laws is widely prevalent. 
3. The growth of formerly extensive mussel beds near 
communities situated along the river has been inhibited by 
the pernicious practice of dumping rubbish of somewhat in- 
destructible nature in the river at those points. While state 
laws are also clear upon this point, the enforcement of them 
seems largely a matter of local sentiment. 
The remnants of the clam beds at Alma, Fountain City, 
and Minneiska, appear to be the ones affected in this’ way. 
The appraisal work here was unusually difficult due to the 
fouling of the collecting apparatus on such obstructions as 
slag, old iron, etc., in the water. From the economic stand- 
point, the least which may be granted is that such rubbish has 
the effect of rendering the mussels but difficultly accessible to 
the fisherman, and he is inclined to let such beds alone. Such 
mussel resources are therefore not utilized. On the other 
hand, it is recognized that materials such as _ sand, coal, 
