How to pressure cook seafood stock
Unfortunately, we don't have tested instructions to can seafood stock, either fish or shrimp. I don't think it's ever been tested for safety.
It would be possible to can the stock by processing for the same length of time as the fish or shrimp itself would be processed. While we realize that would be excessive for a liquid, we don't know how long would be necessary to safely process the stock.
Freezing is certainly a good option.