OYSTER PROPAGATION IN P.E.I. 75 
SESSIONAL PAPER No. 38a 
more frequently as their shell grows larger, yet we are inclined to place the responsi- 
bility for the reduction upon destructive agencies. It must not be forgotten, however, 
that the number of fry secured from the water is not a true index of the number 
present, because a large proportion of every brood of fry will be found near the surface 
on fine days, and deeper down, or at the bottom in bad weather. Hence, the number is, 
to a good extent, an index of weather variations. 
Although the water may show fry of spatting age, it does not always follow that a 
“set” will oceur; if it did, the task of foretelling the date for placing cultch would be 
relatively a simple matter; this act seems to require fine weather. Much work needs 
to be done in this connection before we shall learn all we ought to know, in order to be 
of the best practical use, although what is already known can now be applied to advant- 
age. From the table of fry sizes, it is evident that spatting was prophesied to occur - 
from mid-August onward to the close of September, whenever conditions were fayvour- 
able. It remains to study the cultch to fix those dates. We are not, however, in a posi- 
tion to state the exact date of “setting” from a measurement of the spat until we 
know their rate of growth. This in turn cannot be learned except from a knowledge of 
dates of setting, determined independently. As much, if not most, of the spatting 
occurred after we departed, our data will not be complete; but shell samples sent us 
later throw some light on this question. . 
We have seen from the table that fry, ready to set, were not abundant until mid- 
August. Examination of cultch on the 11th and on the 13th, as well as other dates 
previous to mid-August, failed to reveal the presence of spat. Experimental cultch 
was suspended from a buoy near Malpeque wharf on the 12th, and on a buoy farthest 
from the wharf on the 16th, on Reilley’s lots on the 23rd and on Curtain and Ram 
island shoals on the 21st. Part of the cultch consisted of plain, selected, hard shells, 
and partly of shells of a crumbly nature taken from weathered heaps of “ mussel 
riyud.” Each of the latter shells was coated for two-thirds of its area from the broad 
end, with coaltar varnish. The object of the experiment, was to compare the relative 
efficiency of such a surface with the plain part of the cultch. Coaltar varnish was 
chosen because this is used to cover the bottoms of boats, and a boat was shown on 
which a fine catch of spat had fastened the previous season, thus suggesting that 
this paint was attractive to spat. It is easily understood why this boat carried such 
-a set of spat. A bacterial slime will not form on the tar because of its antiseptic 
qualities; and other vegetable growths will likewise be prevented. Many of the spat 
of other animals, such as barnacles, might reasonably be supposed to avoid that 
surface, the coating being applied to boat bottoms to keep clear of such things. 
There is, however, another. factor to be considered as present in the case of the 
boat, which was not imitated with the tarred cultch. The hottom of the boat in the 
water is an “under” surface and not connected with the bottom. Being .an under 
surface, no silt or sediment ean settle upon it; and being unconnected to the bottom, 
the various crawling animals, snails, ete., would not be able to reach it and browse 
on its collection of spat. We note another fact of importance, viz., the paint was 
applied in the spring, several months before the spat set. Thus the tar had become — 
thoroughly seasoned and hard, its soluble parts, creosotes, etc., that might be offensive 
to spat, had largely soaked out, when spatting began. In the case of our experimental 
eultch, only a few days’ exposure to the water was admissible before the test occurred, 
and the tar was still soft where thickly applied. 
The earliest spat. observed were on shells taken on the 24th on MecNeill’s grounds, 
near Waites cove. Some of this cultch had been planted a week before, and some had 
lain a year on the beds. Several oysters were taken, and the outside of their shells 
was fairly well set with spat. The average spat was 1000 mu in diameter (which 
equals a millimeter or one twenty-fifth of an inch). These, like all young spat, 
showed the larval shell of the size it was when setting occurred, and also the later 
added spat-shell. The larval shell ranged from 320 to 400 mu, and the spat shell 
