"How To Cut Bluefin Tuna"
Quite a few people on the FLA forum have asked for a "how to" showing cutting up and steaking a Blue Fin Tuna. As promised, we will shoot a video of cutting up a BFT on the Karen Lynn this summer. In the mean time I have put together a description and some pictures of how we do it on the Karen Lynn. All the pictures are of Blue Fin, but some are southern BFT and fish from the Mediterranean some they might look a little different to those of you who notice details like that.
I am sure that people on the forum who have experience cutting up BFT's will have some other ways of doing it and I would welcome you to post your tips and idea's. Like most things that require some practice and skill, there is probably no one "right way" to do it. There are however, easier ways to do it and I have tried below to show you one way we have found that is relatively easy. Like most things, the more you do it the better you will get. That said, we have a great resource in our BFT fishery so close to shore and relatively plentiful. Please be conservative about taking fish especially as more and more people get hooked on this fishery. Tuna doesn't keep particularly well in the freezer, so I would urge you to take only fish you intend to eat and do that with prudence.
Please post the inevitable questions and please point out parts below that need clarification. I will edit the post as I get feedback and questions from people on the forum.
Karen Lynn Charters
TUNA ANATOMY 101
The Basic Steps
1. First you want to Gut, Clean and Prep the Tuna as per my previous post "Dressing and Handling of Medium and Large Blue Fin Tuna" that you can find above in the announcements.
You also need to have a good set up to cut the fish. Big fish over 150 pounds will likely have to be cut on the deck. Having a piece of cheap carpet or some burlap sacks can really help. With last years 57"+/- BFT's at the bank, I would often cut them on top of a large Icey-tek cooler with a cheap Home Depot walk off mat underneath them. I'm an old guy and I don't like to work kneeling any more if I can help it.
Having at least one really good large knife is crucial. We have a large 16" butchering knife we bought from a restaurant supply house. I also like to use relatively inexpensive mild steel fillet knives (those ones with the wooden handles) as they hold an edge better than the stainless knives.
2. One of the keys to making it easier to cut up a BFT is too get it really cold before attempting to cut it. Ideally we will leave it in a brine of sea water, kosher salt, and lots of ice for a couple of hours before cutting it. The firmer the meat the easier to cut and by minimizing bacteria the longer it will keep and taste really good.
3. First you have to remove the head, tail, and fins. It is my understanding that this is prohibited by HMS regulations to do at sea. This should probably be done in your harbor, or if you are in Gloucester, maybe at the breakwater. You should make sure you understand the regulations as the penalties for even minor infractions can be severe.
Atlantic tunas, Bluefin, bigeye, and yellowfin tuna must be landed round with fins intact, or eviscerated with the head removed, but with one pectoral fin and the tail remaining attached through offloading. Tunas harvested from the management unit cannot be filleted or cut into pieces at sea."
You want to cut off the Pectoral Fin on the side you start on with a "scalping" shallow cut like you were peeling off the skin on a piece of fruit so you do not cut into the meat below it.
You should now have a clean carcass ready to cut up.
5. Next you want to make the first longitudinal cut. You need to pay careful attention to cutting on the blood line and right down to and along the Tuna's backbone.
6. The Second Cut is when having the right knife will really help. Cut along the Tuna's backbone into the stomach cavity to create a large "quartered" chunk.
After the second cut you should be able to cleanly remove a quartered section of the tuna as below.
7. What I am calling the third cut, actually requires two cuts to complete. First Cut down the middle of the tuna's belly just missing the gristle where the ventral and anal fins attached. Then fold the tuna carcass open as in the picture below and cut along the spine to remove the second quartered section. It will be hopefully a little more clear when you are actually doing it than it sounds here.
8. The fourth cut is again one where a big sharp knife really helps. You now have essentially half a tuna carcass and you are looking down at the backbone intact as below in the picture.
You want to carefully cut out the backbone in one large piece if possible, taking as little meat with it as possible. Below these guys have just made that cut and have lifted off the entire backbone very cleanly.
9. You now have half a tuna carcass with hopefully no backbone. For your last longitudinal cut you simply split the half carcass into two quarters by cutting through the indentation where the backbone was. This will result in you know having four quarters that look something like this.
10. Now for the easiest part which is steaking up the quartered carcass. There are many ways to do this but the way I prefer is to cut across the quartered section through the meat but not through the skin, then take a smaller sharp knife and make a perpendicular cut to free the steak from the large piece of skin on the quartered carcass.
Keeping the quarters in the brine until you are ready to steak each one will real help with fighting bacteria and maintaining freshness. Left in the hot sun for only a short time will really speed up decay.
You now can bag the steaks, and then have some Sashimi and Cold beer!