How would you esplain it?

I noticed something interesting, I think.
Google has a lot of freely available statistics about
usenet traffic and usage patterns, on a group by group basis,
going back a long ways.

Some groups, like rec.woodworking, are statistically stable.
The average number of posts per day for rec.woodworking now
is roughly what it was seven years ago.

But traffic to rec.outdoors.fishing.fly is roughly 80% less
than it used to be.

Do we have fewer fly fishermen?
Or are they.....well. What is it?
How what why.