A couple of things I wrote:
Water Visibility and Light — How clear the water is and the amount of light can also affect fishing. Water that has some debris in it, or that is a little cloudy, does not seem to hurt fishing. In fact, water that contains some sediment usually offers better angling than crystal clear water. In addition, fresh water flows into bays and the ocean can also bring considerable food, usually in the form of detritus (although this can also mean a lower oxygen level in the water). However, if the water is too muddy it will affect those fish that use sight more than smell for their meal. Heavy debris can also make fishing nearly impossible. Most fishermen have encountered days when they spent more time removing seaweed from their line than they did in fishing, usually reaching the point where they throw up their hands in disgust and go home.
The effects of light itself are harder to define, but my records show clearly that fishing mid-day, when the sun is bright and water is clear, yields the poorest results. This may be due in large part to the fact that fish eyes are different than human eyes. The eyes of many fish lack irises and their eyes do not adjust to changes in light; eyes in other fish may take as long as an hour to adjust. Because of this, many fish are uncomfortable in strong sunlight and move into shady areas (like under a pier) and others are less active even when feeding. Not surprisingly, dawn and dusk, as well as overcast days, are often the best times to fish.
Another explanation for the mid-day doldrums relates to food and safety. Fish are primarily motivated by one thing, their own survival, and for most this means they are both predator and prey. To do this requires that they look for meals while avoiding becoming a meal themselves. In regards to safety, many fish are less active during the mid-day, sunny, clear-water hours when they may be more easily spotted by bigger fish. As for food, plankton in the ocean tends to move upward at night and downward during the middle of the day. Since plankton attract the smaller baitfish, and these attract larger fish, it seems reasonable that early morning and early evening hours will see more active fish. At the same time, it should be admitted that planktonic effects are somewhat less important in the shallow waters found around most piers than in deeper water areas.
I like to fish between 5 a.m. and 9 a.m. and between 6 p.m. and 9 p.m. These hours are usually the optimum hours when you will have your best success. Early arrival may also yield that highly coveted “hot spot” on the pier, while an evening arrival can often avoid the overcrowding found during the mid-day (tourist) hours. A forth rule is to fish the early morning or early evening hours if possible. Of course, there are many days when the tide or current is wrong or other commitments impact the hours you can fish. If so, simply go, as they say, with the flow; knowledgeable anglers will catch fish throughout the day.
Fish Biology 101—Eyesight and Smell — An interesting and relevant fact when it comes to fish and angling concerns fish eyes. Put simply, most fish cannot focus their eyes (due to the shape of the eyes themselves). The result is a fish world in which nearly all fish are nearsighted. Correspondingly, most fish cannot really identify an object until they are fairly close to it. (Even when a fish comes to a lure from a distance they may be reacting more out of curiosity or changes in the water rather than attacking the lure. Of course when they get close to the lure they can see it, and if the angler’s presentation is correct, they may attack it.) However, since water often has poor visibility to begin with, eyesight is not as important to fish as their other senses in locating food (their prey). Instead, most fish tend to use their sense of smell to hone in or track where the food is, use their eyesight to pinpoint the location of the food, and then use their sight together with taste to determine the desirability of the food.
Of course, not all fish rely on smell as much as others just as the eyesight of fish can vary. As a general rule, fish that use sight to locate their food primarily feed during the day. Fish that use smell to locate their food feed primarily at night. Of interest, fish anatomists have found that fish that have two nostrils on each side of their snout have excellent odor perception; those with only one nostril cannot perceive smells as efficiently. So what? Well, species that dwell on the bottom, where light levels are low, tend to have two nostrils and typically feed by smelling out their food. Natural bait would be best for these species and when I say natural bait I mean bait that is in good condition and does not have an off smell to it.
In addition, almost all fish have excellent night, or low-light vision (approximately 6-7 times more sensitive to light than humans). When the ability to seek out food by smell is combined with some ability to see during the hours of darkness it is easy to understand why many fish bite better at night. Croakers, rays and sturgeon are just a few of the fish noted for biting best at night and striped bass fisherman can certainly attest to the fact that nights are often the best time for Mr. Linesides.
Sharks of course are probably the best illustration of night feeders that rely on their osmic senses to locate prey. Studies have shown that in some sharks two-thirds of their brain is used in the mechanics necessary to achieve an exceptional ability to smell. Most sharks and rays also have something called a tapetum lucidum located behind their eyes, a device whose purpose is to reflect light back through the eye, thus allowing the cornea two chances to use available light. However, even with this interesting device (which enhances vision in the dark or murky waters), most, but not all, sharks have very poor eyesight. It isn’t needed.
