One trick is to dip the paddle in the water till the wood fibers swell and fill the dinks. It works whith a 100% linseed oil finish, not with a turpentine-linseed mix as is often used by paddlers, particularly for the first layer to soak the wood deeper.
Btw, you'll get more dinks on the blades than on the shaft.
Oil is superior to varnish in the long run, but maybe paddle makers are reluctant to warn buyers they'll have to do an aftercare job using a smelly product they're not familiar with.
Also, you'll get a softer touch and a better grip with linseed than varnish that's too slippery.
Loosing one's paddle is a question in cold waters, with a GP that sometimes has no shouldering, especially when using the slide stroke.

: If you use enough linseed oil and it will last forever. I've done some work
: on a tall ship here in Philadephia (the Gazela) and the masts are covered
: in the oil. They don't use it often, but the masts are continuosly
: exposed. Note that they use numerous coats and really slather it on. With
: any oil you need to add it often and really keep the wood saturated. Also,
: I've found that the only thing to use for any wooden paddle that your
: hands will touch if linseed oil, it just feels good, like the finish on
: those carbon fiber paddle shafts. Yuo can probably use anything on the
: blades, though. Oil doesn't keep the wood protected from ding, and varnish
: and epoxy work as "sacrificial finishes." Use the ideas other
: people have said for that part.