The edge · 600 ft · shelf break and canyons

Bigeye Tuna

Thunnus obesus. Prime water reaches Cape Cod Bay in New England right now (74°F at the surface). Fish it around 186 ft down — that is where 70°F water sits off Cape Cod Bay.

LaneThe edge · 100 fa (600 ft)

Depth it holds656–9843 ft

Prime water66–81°F (workable 66–86°F)

Holds in the column164–820 ft down below the surface, over 656–9843 ft of water

Judged onsurface temperature (NASA MUR satellite)

Structurenone

The water column off Cape Cod Bay

The strip is the water itself, coloured by temperature from the surface down to the 600 ft surveyed bottom at that spot — one band per RTOFS model level. The outlined stretch is where Bigeye Tuna's temperature band (66–86°F) and the depth it holds actually overlap. That thickness is the number that matters: it is how much water you can work, not just whether the spot is warm enough somewhere. One model cycle, not a weekly archive — this holds still while the surface map scrubs.

In 3D

Drag to rotate, pinch or scroll to zoom. 3D model traced from a NOAA Fisheries / Jack Hornady, United States government work; public domain reference — source.

How it's fished

Troll the canyon edges at first and last light, or chunk overnight on the drop-off.

Region by region — right now

Region	Season	Prime water	Temp	Fish it at	Months
New England	in season	reaches Cape Cod Bay	74°F	~186 ft	J F M A
Mid-Atlantic	in season	reaches Montauk	75°F	164–209 ft	J F M A M J
Gulf of Mexico	in season	reaches Tampa	86°F	164–321 ft	J F M A M J J A S O N D

"Fish it at" is where this species' temperature band and its holding depth overlap in the water column, from the RTOFS profile (13 levels, 0–300 m) — the depth to actually put a bait, not just the place. "Prime water" is the furthest sampled station on the 100-fathom lane whose surface temperature sits inside this species' band. It is water, not a sighting report.

Charted grounds on the 100-fathom lane

Jeffreys Ledge