Deep dropping or deep chunking is another method for catching large bluefin tuna. The tactic involves drifting one or more rigged baits along areas known to hold large bluefin tuna.
Throughout much of their summer range, large bluefin congregate to feed on concentrations of bait on humps, hills and ridges of the 20 to 30 fathom lines. Once located, large bluefin tuna may continue to be caught by deep dropping for several weeks at a time.
Deep chunking techniques work when bluefin tuna are holding tight on structure and feeding on small hake, squid, and other baits that are found along the ocean floor. Deep chunking also works well in combination with jigging for tuna, surface chunking, or shark fishing. The technique is similar to deep trolling for bluefin tuna, a technique that can be productive in the same areas.
Tackle is surprisingly simple for this type of fishing. Bait varies; anglers report success with a variety of baits such as butterfish, whole squid, ballyhoo, and other small baits. A 50-80 lb class outfit is preferred and braided line can be a big asset in reaching the bottom. A simple 6-12 foot leader armed with a circle hook seems to work well.
The lighter lines used for surface chunking are actually not required at these depths, which makes the fishing a little more consistent in terms of boating hooked fish. The bait is fed out about 50-75 feet, then a 10-30 oz sinker is added on the line with a rubber band.
The rig is then lowered to the bottom, and cranked back up about 10-20 feet. Keeping the bait near the bottom seems to be the key, which warrants selecting the correct amount of weight to match the drift conditions.