172 BULLETIN OF THE UNITED STATES FISH COMMISSION. 



must be added the high summer temperature of the water. During' 

 August the mean was generally above 70° Fahrenheit at the bottom and 

 several degrees warmer at the surface. Occasionally there was observed 

 a midday temperature of 74° F. and once 76° F. at the bottom. Yet 

 this proved an excellent place for our purjiose, a satisfactory percentage^ 

 of the salmon remaining in perfect health from June to November. 



No. 4. — The inclosure in use since 1879 jat Dead Brook, Bucksport. It 

 is located in a gently running stream bordered by marshy ground, with 

 a bottom in part of gravel but mostly of mud, crowded with aquatic- 

 vegetation. The water, supplied by two small lakes among the hills, i& 

 cleaner than the average of Maine rivers, but does not in that respect 

 approach the water of inclosure No. 1. The greatest depth is about 8^ 

 fe^t, but in the greater part of the inclosure it is from 3 to 5 feet. The 

 width of the stream is from 2 to 4 rods, and the portion inclosed is 2,200 

 feet long. The barriers to retain the fish are in the form of wooden 

 gratings, with facilities for speedily clearing them of debris brought down 

 by the stream. 



Better results were expected from this inclosure than from No. 3, but 

 have not been realized. The percentage of .-^almon dying in confinement 

 has been greater, amounting commonly to about 25 per cent of those 

 introduced, and this notwithstanding the salmon are conveyed to the 

 inclosure by water carriage the entire distance (7 miles) instead of be- 

 ing carted in tanks. The cause of the trouble has not yet been discov- 

 ered, but there is good reason for thinking that it lies in some of the 

 circumstances attending the transfer of the fish from the place of cap- 

 ture, and that the inclosure itself is perfectly suited to its purpose. This 

 view is supported by the fact that nearly all the losses occur within 

 a few weeks after the introduction of the salmon and almost wholly 

 cease by the end of July. If the cause of disease was located in the 

 inclosure, we should exi)ect it to be more fatal after a long than a short 

 duration of the exposure of the fish to its action, and that with the 

 smaller volume and higher temperature of August it would be more act- 

 ive than in June and July. 



The above descrii)tion will, I think, give Dr. Bottemanne a sufficiently 

 correct idea of the character of the inclosures we have tried. There are^ 

 however, several other i)oints to be touched upon to put him in posses- 

 sion of the practical results of our experience. 



The facilities for the recapture of the salmon when thesi^awning sea- 

 son approaches must be considered. In the lake at Bucksport village 

 (No. 3) we hoped at first that their desire to reach a suitable spawning 

 ground would induce them all to enter the small brook that forms the 

 outlet, which was within the limits of the inclosure. In this matterour 

 expectations were but jjartially realized. Many of the fish refused to 

 leave the lake through the narrow ojiening that was afibrded them, and 

 were only obtained by pound-nets, seines, and gill-uets, all of which in- 

 volved a considerable expenditure of labor and material. The drawing 



