Ask a room of surfcasters what the tide does to fish and you will get confident, detailed, contradictory answers. They ride the flood up onto the flat. They drop into the hole on the ebb. They come up in the column as the current builds.
Somebody put receivers in one of the most extreme tidal passages on earth and measured it.
The measurement
The Minas Passage in the inner Bay of Fundy is a reasonable place to look for a tidal effect on depth, on the grounds that if it exists anywhere it exists there. Two analyses came out of that one tagging project: a multi-year baseline report, and a paper focused on striped bass overwintering in the passage.
One asked whether depth changes between ebb and flood. The other asked whether fish are detected more at some water levels than others. Neither found a tidal effect.
The baseline report, comparing detections across ebb and flood:
Striped bass showed no difference in depth distribution during ebbing or flooding tides.
Behind that sentence: 3,289 ebb and 4,324 flood detections on one array, 556 and 1,026 on another. The report shows the two depth distributions side by side rather than running a statistical test, but it rests on thousands of detections, not an absence of data.
The paper, testing detection against water level directly, returned a chi-square of p = 0.93 on 13 degrees of freedom — the ratio sitting at roughly 1 in every bin — and concluded that the likelihood of detecting a striped bass is independent of water level.
Two looks at the same project's fish. Same answer.
They do move vertically — just not with the tide
The same paper found a clear vertical rhythm on a different clock, from the six tagged fish detected in the passage over more than one day:
| 90% of detections | |
|---|---|
| Day | 20–37 m |
| Night | 6–28 m |
Deeper by day, shallower at night. That is a real, measured, substantial diel migration in adult striped bass — and it is temperature-modulated on top.
So the picture is not "striped bass hold their depth". It is that light moves them up and down, and the tide moves them side to side. Those are different mechanisms on different schedules, and the folk version blends them.
Where the data come from
Detection in the passage drops away once the current passes about 2 m/s (4 knots), so the result describes the water you can usually fish, not the top of the flood.
The measurements come from the Minas Passage in the Bay of Fundy, one of the strongest tidal passages anywhere, in winter.
What to do with it
Keep reading tide for position, not for depth. The tide is doing something enormous — it moves the water, sets up the rip, decides which side of the bar has current on it, determines when a flat is even fishable. All of that is horizontal, and none of it is in question.
Let light drive your depth thinking. If you want a rule of thumb about how deep to work, the measured signal is diel, not tidal. Shallower after dark, deeper in bright daylight.
And be suspicious of the compound story. "They ride the flood up shallow" is really two claims — that they move with the flood, which the classic accounts describe consistently (Bigelow and Schroeder 1953), and that moving with it takes them up in the column, which neither analysis found. The first can be true while the second is not.
How StripedLines uses this
StripedLines is built for striped bass. It shows what the tide demonstrably drives: current speed and direction, and the water level over structure.