This is normal. Beets, of which Chard is but one variety, are HALOPHYTIC, which means they concentrate Sodium chloride in their tissue. Commercial sugar beet farmers actually spread rock salt on their fields to enhance growth. Asparagus and Land Seaweed are two other halophytic plants that I can remember. The salty taste would probably be more pronounced if grown in an area with naturally saline soils and lower rain, I would imagine.

i have noticed the salty taste in chard (and maybe arugula?) before but didn't know why-cool!

i am confused by the first post though, i thought chard was biennial?

Yes they are Biennial and don't produce flowers until the second season , even here in Southern CA.
And the Ruby Red Chard has more of a salty taste than the Fordhook Giant or the Winterby

over here(sub-tropics they are our winter crop planted late summer early autumn) one would be very lucky to get 2 years out of chard/silverbeet, we grow fordhook variety. i'll pay more attention the next meal i have of it which will be tonight as our plants are in prime right now just before their season ends (may be due to our drier hot long summers). have never had plants bolt they just get less than healthy looking and that is when i pull them. but would imagine also eating leaves from plants that have bolted could infuence the taste like in lettuce etc.,.

len

Here is a link that might be useful: lens garden page