Dawn, dusk and low light: why fishing often improves

What changes when the light changes

The difference in brightness between midday and a moonless night is enormous, and most of that change is packed into a short spell around sunrise and sunset. The eyes of fish adjust to it, but in many species the adjustment takes time.

One common explanation for the dawn and dusk bite follows from that. Predators whose eyes cope well with dim light may have an advantage over their prey while the light is changing. Twilight is also a changeover period: animals that are active by day are heading for shelter and those active at night are coming out, and both are exposed while they do it.

Anglers also commonly report that fish are less wary in dim light. They may move into shallow water they avoid under a high sun, and lines, boats and people on the bank are harder to see.

Under water the dim period lasts longer than it does on land. When the sun is low, more of its light reflects off the surface instead of entering the water, and depth and colour in the water reduce it further.

Temperature and feeding movements

In warm months, shallow water heats up through the day and loses heat overnight, so it is usually coolest around dawn. For fish that find summer shallows uncomfortably warm by afternoon, early morning can be the easiest time to use them. In cold months the pattern can reverse, and the mildest part of the afternoon is sometimes the better bet. How temperature affects fish is covered in the article on water temperature and fish activity.

Prey moves on a daily schedule too. In lakes and in the sea, many small drifting animals rise toward the surface around dusk and go deeper again around dawn. Small fish follow them, and larger fish follow the small fish. Many aquatic insects are also most active toward evening.

Civil twilight in plain terms

Twilight is the period when the sun is below the horizon but the sky is still lit. Civil twilight is the brightest part of it, defined as the time when the sun is between the horizon and six degrees below it. In the morning it runs from civil dawn to sunrise; in the evening, from sunset to civil dusk. In clear weather there is usually enough light during civil twilight to see what you are doing without a lamp.

How long civil twilight lasts depends on latitude and season. Near the equator the sun drops steeply and it is over in little more than 20 minutes. At middle latitudes it is nearer half an hour and longer around midsummer. At high latitudes in summer it can last for hours or continue through the night.

The practical point is that usable light arrives before the published sunrise and remains after the published sunset. An angler who reaches the water at sunrise has already missed part of the morning window.

Cloud, shade and other kinds of low light

Dawn and dusk are not the only source of dim light. Heavy cloud cuts the light reaching the water all day, and many anglers find that fishing stays steadier through the middle of an overcast day than a bright one. Wind ripple scatters light at the surface. Coloured or turbid water, depth, and the shade of banks, trees, weed and structures all do something similar.

Put simply, bright, calm, clear conditions tend to squeeze activity toward the ends of the day, and dull conditions tend to spread it out. There are plenty of exceptions. Some species feed mainly in full daylight and others mainly in darkness. On the coast, many anglers look for a dawn or dusk that coincides with a good stage of the tide rather than relying on either alone.

Preparing to fish in dim light

Fishing the ends of the day means arriving or leaving in the dark, so preparation matters more than it does at midday.

Carry a headlamp and a spare light or spare batteries. A dim or red setting is easier on your night vision and on the people around you.

Be visible. On a boat, show the navigation lights required where you are. Paddlers should carry a bright white light, and anyone near a road or a boat ramp benefits from reflective clothing.

Know the way back. Walk the route in daylight first and note steps, drops, soft mud and slippery rock. Afloat, know where unlit hazards lie and how to find the ramp or mooring in the dark.

Check the tide. A rising tide can cut off rocks, sandbanks and gullies, and it is much harder to notice in the dark.

Dress for the temperature after sunset, wear a life jacket on or near deep water, and tell someone where you are going and when you expect to return.

CatchWindow location pages show sunrise and sunset for each location, with tide predictions where a tide station applies, which makes it easy to see when the two line up.

The practical takeaway

If you can only fish for two hours, the two around first light or last light are a reasonable default on unfamiliar water. Arrive before civil dawn or stay until civil dusk, treat heavy cloud as a possible extension of the window, and prepare for the dark as carefully as you prepare your tackle.