zfs send compression query

[John]

Hello list,

I have a selection of zfs datasets that I'm snapshotting to a remote
freebsd server. Thing is, I want to use less bandwidth.

Here is an example incantation, from the server:

$ zfs send -R vms/132 at 2016-01-06.2122 | ssh backup@[remote_ip] \
zfs recv -Fdvu storage/snapshots

How do/would I use xz -9 to compress the stream over the wire? The
uncompressed snapshot is 57GB. 7zip (using lzma2 like xz) will
compress it to 12GB.

thanks
-- 
John