I do not have the answer you want, but as it it your first post and no one else answered i will try anyway.
There is no good reason I am aware of based on public information.
There has been 2 substantial investors trading recently and they may have contributed. Global factors have only a minor affect IMO.
Since your post there have been negative announcements regarding the EPA demanding Tassal destock some of their leases and that may have caused the drop in price. It was reported by 7:30 report and Landline. I think the price is currently too high and agree with Morningstar's estimate copied below.
"Fair Value Estimate
4.20
TGR is trading above its Morningstar Fair Value Estimate."
Cheers
TGR Price at posting:
$4.42 Sentiment: None Disclosure: Held