Reading the conditions

The single most important variable in sea fishing: what moves the water, when it moves fastest, and why the same mark is a different place at every hour.

A literacy page rather than a mechanism page: what the numbers in a tide table mean, what they are measured from, what they do not tell you, and why the height matters as much as the time.

Not how tides work, and not how to read a table — which state of the tide fishes, and why the answer is a property of the mark rather than of the tide.

The period when the tidal stream stops before reversing. It behaves like neither the flood nor the ebb, it is frequently the worst fishing of the cycle, and on some ground it is the only fishable window there is.

Fish in current sit where the food arrives without the effort of holding in it, which makes eddies, seams and obstructions predictable rather than lucky.

In a running tide the problem is not finding fish but keeping a bait where you put it, and every part of the solution — lead, line, rig and timing — trades holding power against presentation.

An estuary is a salinity gradient that moves with every tide, and the fish move with it — which is why the same spot fishes like three different places over a tidal cycle.

The tide closes your exit long before it reaches where you are standing, and this is the commonest way a coastal session becomes a rescue.

A weather window is a period in which conditions are workable rather than merely forecast, and reading one means understanding wind, swell, tide and their interactions rather than a single number.

Wind moves the surface layer downwind, and everything floating in it goes too — which is why the uncomfortable bank is usually the productive one.

Surf stirs food out of the sand, colours the water and gives fish cover to feed in the shallows — and the features that make it productive are the same ones that make it dangerous.

Wind does not defeat a cast by being strong; it defeats it by exposing a slow, wide loop. The fix is line speed and loop shape, and the second fix is standing somewhere else.

There is no wind speed that is safe and no wave height that is not. What decides a kayak day is how wind, tide, swell, temperature, daylight and your own range combine — and the most useful answer this subject has is often that today is not the day.

Conditions deteriorate faster than divers notice, because the diver is absorbed, cold and progressively less capable of judging — which is why the decision is agreed on land before anybody has anything invested.

Anglers are certain that pressure affects fishing and the controlled evidence is thin. What is well supported is that fronts change light, wind, temperature and water — and those are enough to explain most of it.

Three different situations that are routinely collapsed into one question, with different mechanisms behind each — and in fresh water the largest effect of rain has nothing to do with the rain itself.

The moon has a strong, well-evidenced effect through tides and a real one on some spawning cycles — and a much weaker case as a general predictor of feeding.

An angler on open water or an open bank holding a long carbon rod is a poor place to be in a thunderstorm, and the decision that matters is made before the storm arrives.

Water removes colours in a fixed order with depth, so a lure's colour changes as it sinks — and that physics does not add up to a ranking of which colour to tie on, however much anglers would like it to.

Water absorbs light unevenly by wavelength, so red is effectively gone within the first few metres and every colour follows it — which means the character most people would name first is the one least available when it is needed.

Turbidity shortens the distance at which anything can be seen, which shifts the balance from sight-hunting to vibration and scent for fish and anglers alike.

Visibility decides the range at which fish are seen, the confidence with which they are identified, and — the part that matters most — whether a buddy can watch you at all.

Visibility, current, swell and thermoclines decide whether a dive happens and what it can achieve — far more reliably than skill does.

Fish are ectothermic, so water temperature sets their metabolic rate — and therefore how much they need to eat and how hard they will work for it.

A fish's body temperature is the water's temperature, so temperature sets its metabolic rate, its oxygen demand, its digestion speed and therefore how much and how often it needs to eat.

Light level, temperature, prey availability and digestion state explain most of what anglers call feeding windows — and they explain it better than the calendar-based systems that claim to predict it.

Above a certain water temperature the arithmetic of catch and release stops working, because the fish needs more oxygen to recover and there is less of it available. The honest response is to stop, and it is rarely said.

A genuine and mechanistic effect rather than folklore: at low light a predator that sees better than its prey has an advantage it does not have at either extreme, and the window is short.

Cloud is an optical variable rather than a mood: it changes how much light reaches a given depth, how exposed a fish in shallow water feels, and therefore where in the water column it is willing to be.

Darkness changes which sense the fish is using, how close it will come, and every single thing about the angler's own safety — and the third of those is the one that decides whether a night session is a good idea.

After dark vision stops being the dominant sense for both the fish and the angler, and lure choice changes for a reason rather than by convention: what the fish is detecting is displacement and silhouette rather than detail.

Squid fishing concentrates after dark not because squid prefer darkness, but because light creates a food chain in the water and the squid arrive at the end of it.

Darkness does not add new hazards so much as remove the cues that let anglers avoid the existing ones, and it does so at the time of day when help is furthest away.

A river coming up, at its peak, and falling are three different fisheries. Most of what is said about high water is true of exactly one of them, and knowing which is the whole skill.

A river is a repeating sequence of the same few features, and each one holds fish for a different reason. Learning the sequence means arriving at an unfamiliar river already knowing where to look.

Across most of the world's land area a river is a seasonal event rather than a permanent feature, and the fish that live in one are adapted to surviving in disconnected pools until the water returns.

One treatment of the seasonal round rather than four near-identical pages, written from the two things that actually change — temperature and day length — so that it works in either hemisphere.