8 U. 8. BUREAU OF FISHERIES 
each end and between all the crates are placed 2-foot plank walks, 
giving ample room for working on all sides, which is a great con- 
venience in handling fish and procuring eggs, especially in stormy 
weather. The pens are now made of boards 3 inches wide, nailed 
114 inches apart, which gives sufficient space for free circulation of 
water. The lumber is dressed on all sides and all inside corners are 
rounded, as the fish injure their noses on square corners in their 
attempts to escape. All parts of the pens are interchangeable and 
easily taken down for storage, being held in place by 4- inch log bolts. 
The pens are fastened to the booms by log bolts 6 inches long. 
Much depends on the work of transporting either whitefish or pike 
perch from the nets to the pens, not only in moving the fish with the 
least possible injury but in the saving of time, so that greater num- 
bers may be penned and the risk of holding the fish in the supple- 
mental nets may be minimized. 'Tow cars have been used, but they 
retard the speed of the steamer fully one-half, and tanks on the 
decks of the steamers have therefore been adopted. It is better to 
have several smaller tanks than one large one, as the fish can be 
dipped more readily from the small tanks and the water is not so 
violently agitated during rough weather. A convenient size is about 
6 feet long, 4 feet wide, and 3 feet deep. The tank has two lds, 
submerged about an inch, arranged to open crosswise of the center 
and held by lugs below and by pins above. The lids are made of 
3-inch boards nailed firmly upon cleats on the upper side, with 
about one-fourth-inch space intervening. ‘This prevents slopping in 
any weather when fish should be handled. The tank is smooth and 
has no obstructions inside. A 2-inch hole at the bottom at one end 
is provided for drawing off water, and one of the same size is made 
within 3 inches of the top for an overflow, when fresh water is being 
added. Fresh water must be furnished, the amount varying with the 
number of fish. This can be supplied with a donkey pump, the hose 
being carried from one tank to another as required. With three 
tanks of the dimensions given above, six or seven hundred pike perch - 
of average size can be transported. 
For coating these tanks inside, as well as all tanks and troughs 
about the hatcher y, coal tar with about one-third its bulk of good 
spirits of turpentine, free from benzine, is applied as hot as it can be 
made. This forms a smooth, hard, strong, impervious coat, which 
lasts well and is cheaper than’ asphaltum varnish. 
The use of a proper dip net in handling the fish is of great impor- 
tance. The splitting of fins and removing of scales is to be avoided 
as far as possible where any species of fish is to be penned. ‘The 
scales of the pike perch are not so easily abraded as those of the 
S hitetich, but it suffers even more as the result of i injuries, owing to 
the higher temperature of the water at the time it is penned. The 
ideal net would be made of cofferdam rubber of suitable thickness, 
perforated at frequent intervals so as to permit the free discharge 
of the water—that is, a rubber ne e necessarily 
in use and subject to rough handling especially a in freezing weather, 
their expense would be considerable. The hoop of the net used at 
the Put in Bay station is of three-eighths-inch spring steel wire, that 

