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Seafood Safety -
A Guide to Handling Your Saltwater Catch

Anglers sometimes wonder why the fish they catch don’t taste as fresh as the fish served in their favorite restaurants. Fish is highly perishable food, and storing or processing is improperly can cause serious problems. Good handling practices (techniques for keeping fish fresh after they are caught) are based on the principles of fish biology.

Fish Biology 101
Although saltwater finfish come in many shapes, sizes and colors, they do have several things in common. They all have some type of backbone, they all breathe through gills, and they are all cold-blooded. Recreational anglers most frequently encounter two classes of fish.

Bony fish have a backbone and a skeleton made of bones. These include groupers, snook, mullet, and snapper. Cartilaginous fish, or Elasmobranchs, have a skeleton made of cartilage instead of bones. These include sharks, rays, and skates.

The part of the fish generally consumed is the muscle. Fish muscle is actually small blocks of fibers bound together by connective tissues. Fish use darker muscle for steady, continuous swimming. Lighter muscle serves as an energy reserve for sudden bursts of speed.

What Happens When Fish Are Caught?
Changes take place to a fish that is caught as a result of its biological composition and its environment. These changes begin as soon as the fish is hooked and continue after it dies.

When a fish is hooked, it engages in a struggle for its life. It gets energy for this struggle from the glycogen (starch) in its muscles. The longer the fish struggles, the more it depletes its energy reserve. The depletion can cause the fish’s flesh to lose some of its natural sweetness, and metabolic products that can affect its flavor and texture begin to accumulate. These changes begin even before a fish is landed. Therefore, even though a good fight can be a lot of fun, fish used for food should be landed quickly.

As soon as a fish dies, an irreversible spoilage process begins. This process occurs through the activity of enzymes and bacteria. Enzymes that normally regulate a fish’s metabolism can work unchecked after it dies. Digestive enzymes may begin to digest the fish itself, causing belly burn or softening of the flesh around the gut. This is especially likely if a fish is caught while feeding, since its digestive enzymes are already active. Other enzymes in fish muscle can also begin to affect the flavor and texture of the fillet. They enzymes work rapidly at warm temperatures.

Fish are also subject to bacterial degradation after death. Natural barriers that protect fish while they are alive break down when they die. Bacteria from the environment and the
gut can grow and multiply in fish tissue. This activity diminishes fish quality and eventually causes spoilage. Bacteria also grow rapidly at warm temperatures.

Finally, the high unsaturated fat in fish is also affected by oxygen in the air. Oxygen reacts with this fat to produce rancidity. Fat oxidation can be a serious problem if the fish are to be frozen or stored for very long. This is one reason why fattier fish like bluefish do not remain in good condition during frozen storage as long as leaner fish like flounder.

How to Handle a Fish to Minimize Spoilage
Many fish are wasted because of mishandling. The quality of the fish you bring home depends on how far the normal spoilage processes have progressed. Although you cannot stop these processes, by handling your catch properly you can control the rate at which they occur.

The factor that’s easiest and most important to control is temperature. Try to keep the internal temperature of fresh, unfrozen fish as close as possible to 32˚ F. The best way to do this is to pack fish in ice or ice water. Make an effort to store fish on ice as soon as possible for complete and rapid cooling. The table below gives the shelf life of lean fish at various storage temperatures (“Shelf life” means the amount of time before fish is judged unacceptable by those who taste it).

Temperature control is even more important if you plan to refrigerate fresh fish for several days or freeze it. At summer temperatures about 80˚F, fish can lose most of its shelf life in a few hours. Cool your catch quickly to keep it from deteriorating to an unacceptable level of quality before it is refrigerated or frozen.

If possible, avoid bruising, gaffing, or puncturing the fish as you land it. Breaks in the skin can cause bruises and bloodspots and allow bacteria to enter the fish. Bruised flesh looks bloody, and bruises and bacterial growth cause soft spots resulting in a reduced-quality fillet.

Gut fish as soon as possible after you catch them. Keep the entrails intact if possible. The stomach and intestines contain enzymes and bacteria that can contaminate the edible part of the fish and accelerate spoilage. Bile from the gall bladder will also taint any part of the fish it touches, and it is very difficult to wash away. Rinse the gut cavity to remove blood, slime, and bits of viscera.

Keep your work area clean and avoid contaminating other fish with the gut contents. Wash your work area and knives after each gutting operation. Finally, do not allow your fish to become tainted by coming into contact with oily or dirty areas of a boat or dock. Immediately store the fish on ice.

To preserve the quality of the fish you catch handle them as little as possible. If you do a good packing job while you are fishing, your cooler of iced fish can go right into your vehicle. Check to make sure there is enough ice left to keep the fish cool until you get home.


Resource:

Handling Your Catch: A Guide for Saltwater Anglers by Ken Gall, NewYork Sea Grant Extension Program.