Freeze Fish: Cooling the Catch

Far too many fishermen freeze fish improperly. They
end up ruining their catch by not giving it proper field
care. Instead of freezing fish, or letting it sit in
a slushy mixture of ice and water, you should superchill
your catch, and ice it in a way that lets the water
drain off. That will assure high quality meals when
you get home.

It’s an all too common occurrence. You spend a few days at a fishing camp, where the operator graciously freezes your catch for you. On the drive home you dutifully add ice to the cooler, occasionally draining off the melt water.

Then, when you get home, you discover that the fish has defrosted despite your best efforts. You cannot refreeze fish without a loss of quality and flavor. Which means you have to use it right away, share it with friends and neighbors, or dispose of it.

The last time this happened to me we’d been on an Atlantic salmon fishing trip in New Brunswick. Atlantics are too rare, and fishing for them too expensive, to let them go to waste. When we got home, despite being exhausted from the drive, we had to first cook the fish to assure it’s quality.

There had to be a better way to freeze fish. Turns out there is.

What you need to understand is that water ice exists in a steady-state solution at 32 degrees, when it can be both liquid and solid. When you ice-down frozen food, the ice actually defrosts it as it brings it up to the 32 degree mark.

If you have a large amount of frozen fish, enough to actually fill a cooler, you’d be better off not putting ice in it at all. After you freeze the fish, put the frozen fish in the cooler, seal the lid seam with tape, and go about your business. Wrapping the cooler in some insulation, such as a sleeping bag, helps as well.

But there’s an even better way to freeze fish. If you superchill your catch, you can keep it safely for at least a week before it has to be frozen. Here’s how to go about it:

First off, one of the cardinal rules about fish is to never allow it to sit in plain water for any length of time. That’s a surefire way of promoting bacterial growth and deterioration. This is easy enough at a fishing camp; you merely leave the drain open on your cooler. Do that in your car, on the drive home, however, and you’ll have quite a mess.

The alternative is to build a drain rack that sits in the bottom of the cooler. This is merely a series of spaced wood slats, nailed to a couple of cross members. The whole thing sits two to three inches high. Be sure and cut some groves in the support pieces, so that water can flow freely.

With such a rack, your fish remains above the melt water, which can be drained off periodically.

In order to freeze fish using the superchilling method there are two phases. In phase one you immerse the fish in a slurry made of ice and brine. If you’re fishing in the ocean, merely use sea water. If not, make a brine consisting of one cup course salt (I like canning salt for this) dissolved in one gallon of water.

Fill a washtub or a second cooler with crushed ice, and pour the brine in just to the level of the ice. Bury the fish in this slurry, and let it sit for a half hour. Whole fish can go directly into the mixture (be sure that their body cavities are filled). Filets, steaks, and seafood such as shrimp, scallops and crab should first be put in sealed plastic bags.

After the quick chill, transfer the fish to a second cooler that uses a mixture of salt and ice to maintain the superchill. Again, using a washtub or second cooler, combine 20 pounds of crushed or shaved ice with one pound of course salt. Put a four inch layer of this mix in your cooler, then push the drain rack down into it, adding more ice to assure that the rack is covered.

Lay the fish down on that ice, in one layer, keeping them separated by at least two inches. Cover with four inches of salted ice, and add another layer of fish. Continue layering in that manner until the chest is full, finishing with a layer of ice.

Shrimp, scallops, and picked crab can be transported the same way. These should be put in plastic bags first, in single layers, and laid flat between the layers of salt ice.

For the trip home, you might need a second cooler filled only with the salted ice, so you can replenish it to keep the fish covered at all times. This beats having to mix the salt and ice while on the road and is a much more efficient method to freeze fish for transport.

Every time you stop, be sure and drain any melted water so that it never goes above the level of the rack, replacing it with an equal volume of salt ice. You’ll find, however, that the salt ice melts much more slowly than plain ice, because it’s actually colder.

According to the Georgia Sea Grant, even the initial superchill isn’t necessary to freeze fish if you use the layered, salted-ice system. As you amass your catch, merely add them to the cooler, covering with more salt ice each time. The Sea Grant people recommend that you leave the drain cock open if possible. And that you keep the cooler in the shade, if you can.

How effective is superchilling to freeze fish? Gutted and gilled fish, merely kept on ice, will stay fresh for from 48 to 72 hours. Using salted ice, they’ll remain wholesome for up to a week. Quite a difference. And well worth the extra effort it takes.