Strong currents can sometimes overwhelm the swimming ability of baitfish and concentrate them, even if there are no plankton for them to feed on. This strong association of plankton, baitfish and gamefish with currents frequently explains why fishing will slow down or even stop when the current ceases. During slack water there is no current to concentrate either the plankton or baitfish, and they will be dispersed. Generally the stronger the current, the more the possibility of concentration and disorientation of baitfish. Thus the increased opportunity to catch the larger fish who feed on the baitfish.
Tides can cause problems for the fly fisher.
During spring tides, the water will reach higher up on the beach essentially cleansing it and carrying seaweed and other debris into the surf zone and then further seaward. A storm or strong period of onshore winds could produce the same cleansing effect on a beach. Tides are especially important for beach fishing. Their effects will vary depending on the character of the beach, especially its slope, the tidal range, and weather and sea conditions such as wave height and direction of the wind. Beach characteristics will be the subject of another article.