r.

"Over three and a half billion eggs and small fish were distributed last
year, if I remember rightly," was the reply. "Of course, a large
proportion of these fish did not reach maturity, but perhaps half a
billion did so, and half a billion fish is an immense contribution to
the food supply of the world."

"But aren't there always lots of fish in the sea?" asked Colin. "When
you come to compare land with water it always looks as though there must
be so many that the number we catch wouldn't make any sort of impression
on them."

"Think a bit," said the professor. "You've just come down from the
Pribilof Islands. How did you find matters up there? Had the catching of
seals been harmful, or were there so many seals still in the sea that it
didn't matter what line of hunting went on?"

"Of course, pelagic sealing had nearly killed off the entire species,"
said Colin, "but, somehow, fish seem different. Oh, yes, I know why.
Seals only have one pup at a time and fishes have thousands of eggs."

"That's a very good reply," the professor agreed, "but why was it that
pelagic sealing was so bad? Was it done all the year round?"

[Illustration: MILLIONS OF THESE HATCHED YEARLY.

Brook Trout just hatching, showing fry with egg-sacs still attached.

_Courtesy of the National Geographic Magazine._]

"No," said Colin, "principally when the females were coming to the
spawning ground."

"And the Pribilof Islands are only a small place. Especially when
compared to the range of oceans the seal cover during the rest of the
year?"

"Very small."

"Then," said the other, "it is easy to see that the respective size of
land and water has very little to do with the general fishery question.
But if a seal or a fish must come to the land or to narrow rivers to
spawn, it follows that man possesses the power to determine whether
spawning shall continue or not, doesn't it?"

"Yes," agreed Colin, "I suppose it does."

"And if you protect the seals, the herd will increase."

"It ought to."

"Very good. That is just the work we are doing here. The salmon come
into fresh water to spawn--just like shad and a number of other species
of fish--and when you kill a salmon just about to ascend the river, you
destroy at the same time the thousands of eggs she bears."

"But I thought salmon were always caught running up a stream?" said
Colin in surprise.

"They are," was the quick response; "by far the larger number are caught
that w