
I have friends in BC Canada who own have a spawn on Kelp fisherie (they grow Herring roe on kelp sea weed and farm it)
Their dogs (Malamutes) get fresh roe and Ive known them for 15 years.
A tip I picked up from them (as often the roe we get over here has been shipped and stored in Brine) is To test the salinity level, simply taste the roe or place it between your teeth and inhale a bit of air through the little egg.Rinse thoroughly with water.
HTH :)
(I'll email them and see if I can get nutritional info from them for you)