BUTTE Montana Fish, Wildlife and Parks is investigating a report of people joyriding side-by-side vehicles in the Big Hole River at a fishing access site in Melrose.A person wishing to remain anonymous posted video of a group of people cheering as at least two side-by-side vehicles were driven into the river and spinning out in the water at the Salmon Fly Fishing Access site late Saturday afternoon.WATCH THE VIDEO HERE: FWP investigating video that shows side-by-sides joyriding in Big Hole RiverFWP Fish Biologist Jim Olsen told KXLF that this is not just a violation of Montana law to drive motorized vehicles in rivers and creeks, but that area is also where brown trout are currently spawning.The Big Hole Watershed Committee also shared the video on Facebook, stating in the post: Folks, the Big Hole is precious. It is unique. It has immense value- the kind you make a living from and much more that you cant put a price on. This access site is ground zero for brown trout spawning. This is not an ok activity, in fact its a violation of 310 laws.The Big Hole River has been struggling with decreased trout numbers in recent years, and Olsen said activities like the ones recorded Saturday can make this issue worse.No citations have been issued in this matter as of Tuesday and it remains under investigation.