The clue to all of this is in the Job spec on the Gama website. Without going into too much detail have a look as to the type of flying that this position is asking for. I agree the hours for a Caravan F/O are a bit high in response to he inital post about this, but it suggests there is a reason for it. Aerial survey work takes on many forms from geographical mapping to fisherie protection to double 0's in the sky.
Gama are a business/corporate outfit flying jets. We may have to think deeper as to the fact that this could be a contract that they have undertaken on behalf of someone and that someone could be setting the ''bar'' on hours.
To be fair that job has been up on their website for a while and with the website updated today as mentioned above, and the job still there, it may suggest that the role/roles aren't fulfilled yet. Worth sticking in an application regardless because they may not find candidates with the correct pre requisites. You never know. Plus if you're starting out and you manage to get in, there may be that possibility of transfering across onto their jet fleet in the future and start your jet career.
All that said..........good luck