For a quick fix you should try rock salt. Cover them completely in the salt and that should pull away a lot of the moisture and toughen them up. If you don't have rock salt you can try kosher salt or sea salt - I wouldn't use iodized table salt though. Longer term you could try a commercial bait brine maybe with some color and "bit enticer" but for the short term try rock salt. Good luck.
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purpledog