626 REPORT OF THE COMMISSIONER OF FISHERIES. 



boundary (fig. 2, pi. n). a This fence consists of rough boards driven 

 into the mud a short distance apart, and supported at intervals by strong 

 stakes driven firmly into the bottom. It is necessary to have the top 

 of the fence several feet higher than the highest water, to prevent the 

 fish from leaping out. A woven-wire netting 2 to 3 feet high is often 

 added to the top of the fence for this purpose; it is not practicable to 

 use the wire netting under the water, as the fish would become badly 

 bruised in attempting to get through it, or by dashing into it without 

 seeing it. The pens may be of any size, from small ones, which will 

 accommodate only one or two hundred fish, to those covering an extent 

 of some 2 or 3 acres. Larger ones than this are probably not practicable 

 on account of the difficulty that would ensue in attempting to get the 

 fish out of them; obviously the water can not be drawn off and the pen 

 drained, so the only way of taking the fish is with a seine. This is 

 done by setting the seine around the perimeter of the area, close to 

 the fence, and then hauling it to one corner of the inclosure, where the 

 fish can be gathered into the bag of the seine (fig. 2, pi. n). 



As a rule there is not enough natural food in these pens for the 

 sustenance of the fish, and in order to keep them from falling away 

 greatly in weight it is necessary to supply them with food. The 

 necessity of removing the fish with a seine makes it impracticable to 

 build the pens where there is plenty of vegetation to supply the fish 

 with natural food, since much vegetation would interfere greatly with 

 the seining. 



Pens should be built in places sheltered as much as possible from 

 storms, for the high waves are apt to break down the fence and allow 

 the fish to escape. Unusually high water and severe storms caused 

 great damage in this wa} r in Sandusky Bay and vicinity in the summer 

 of 1902, one pen, in which there were said to be 40 tons of carp at the 

 time, being broken down in places so that all the fish were lost. 



Portions of marsh which have comparatively narrow openings lead- 

 ing into them are sometimes converted into ponds by throwing 

 embankments, or more often building board stockades, across the 

 narrow places. Such ponds usually have the advantage of containing 

 plenty of natural food, but trouble usually arises when it comes time 

 to take the fish out, as the places are not adapted to the use of a seine. 

 In some cases the embankment or fence, with a convenient gateway, 

 is constructed early in the spring and the gateway is left open until 

 a large number of fish have entered the shallow water of the inclosure 

 for the purpose of spawning, after which the gateway is closed and 

 the fish are entrapped, to be seined out at leisure. At one or two 

 places great areas of marsh were cut off in this way and the fish were 

 prevented from returning to the larger open waters; but this was of 



a A photograph of a carp pen similar to this is shown in the Illinois fish commissioner's report for 

 1900-1902. 



