Properly caring for your catch not only will make it taste better, it can keep you from getting sick. When catching and eating tuna, mackerel, bluefish, mahi, and other related species, special attention is needed to prevent scombroid poisoning. Also, referred to as histamine toxicity, these fish contain high levels of histidine, which in this form is harmless. However, if bacteria are allowed to thrive, they can convert histidine into histamine. When consuming fish with histamine your body may respond with symptoms typical of an allergic reaction. Cooking, smoking, or freezing does not eliminate the histamine once it has been converted. It may kill the bacteria, but once histidine is created it does not change back.
Properly caring for your catch in important. Don’t slam any fish onto your deck or into your cooler. Prevent meat bruising by gently handling your catch. Many commercial boats have rubber “landing mats” to accept the fish as it is laid on the deck. Grab a hose and your camera and take a quick picture. Better yet take the picture of the fish while it’s still in the water. Putting the saltwater washdown hose into a tuna’s mouth will help calm the fish down and prevent a chemical reaction known as “burn.” Down south they actually swim and revive their fish before boating. This procedure can reduce and reverse the burn effect.
The next step is to quickly and humanely dispatch the fish. There are 2 primary tools that are a must for this process. Others can be used, but these allow consistent and seamless results. The first is the ice pick by Cuda. This is a large heavy duty, stainless steel tool. The oversized handle is rubber coated to ensure a good grip. The tool is used for spiking the fish. This will dispatch the fish, preventing it from thrashing around. This preserves the meat and allows you to work on your prize without incident. Find the soft spot on the top of the tuna’s head. Insert the spike on approximately a 30-degree back angle. The depth will vary with the size of the fish. The fish is now brain dead but metabolic systems are still functioning. Remember this is a prized catch for consumption, so using a rusted screw driver or nasty bait knife will result in wasted meat. The second tool is a blood drop knife. This is a special knife that severs the blood line perfectly every time. No guessing, searching and subsequently ruining meat. A quick poke immediately behind each pectoral fin is all that is needed. Another cut at the tail to the bone, but not through it, should be made as well. If done properly this will prevent lactic acid build up and the burning of the meat. Allow the fish to completely bleed out. This is best done in a padded empty tuna bag or large barrel which allows you to control the fish and makes for a quick cleanup. A big mistake many anglers make is they ice their catch as it is bleeding out in an ice slurry. The fish is brain dead, but the nervous system is still intact and functioning. Icing it then will cause the fish to shiver since it is warm blooded. Shivering will cause burn as lactic acid builds up, deteriorating the meat’s taste and quality. Waiting until the fish is in rigor prevents this. Japanese processing goes one step further by tapping the entire spine in an effort to completely prevent any shivering and induce rigor. The process is called “ike jime.” Once rigor sets in make a circular cut around the anus. Sever the gill, which allows you to remove them and the guts together as one piece. Leaving the inside membranes and outside skin intact prevents any damage from contact with ice or freshwater.
Hose off the fish with a saltwater washdown. Either slip the fish into a salt ice slurry (preferred) or pack them out in ice. Be sure to get ice down into the body cavity. If using insulated fish bags fill them and seal them. Air is the enemy of ice.
Proper core temperatures are a must in preventing bacteria. When you are cutting them back at the dock and the meat closest to the bone is cold to your touch, you did it right. With attention to detail you will see a dramatic difference in quality and possibly prevent food poisoning.