Those are quick disconnect fittings. You need a tool that fits around the small hose, and slides into the larger fitting to release the clip. You can get cheap ones at your local auto parts store... and they look like this:
I think the automotive and other industries have gone to these types of connectors to eliminate the potential problems of technicians dealing with high pressure fittings that could leak or cause a hazard as in the case of fuel lines.
When making my pressure gauge tool (like shown in the Seadoo manual), the hardest part to find was the male connector. I had to cut the male end off a purchased one foot piece of metal fuel line. I have also acquired these parts from a Seadoo dealership, by just asking them to give you one of the bad fuel modules that they just throw away.