Hummingfrog is absolutely correct the shortage is of experienced SAR drivers.
What is happening is that the transition from BHL to CHC and the new aircraft requires a slip crew. So effectively CHC require the same number of SAR crew for the slip crew as they would for a new base. They need 4 SAR Captains, 4 SAR P2's and 4 SAR crewmen. Obviously there isn't this sort of experience hanging around on street corners so my guess is that they'll start digging up old SAR S61 drivers to cover (defib on standby)!
To all the wanabees out there I would say that SAR is the future get in there if you can....