User Guide 

Different species of fish need different sets of environmental conditions.

Many factors affect fishing, and this may vary based on where and what species you are fishing.

Fishing is not an exact science as there is no lack of speculation about the “best” and “worst” conditions depending on who you talk to. Depending on the species and the development stage in their life cycle, fish can be found in many different locations. There is usually a consensus as to what conditions fish prefer to exist in; however, fish can tolerate a wider range of conditions and can be found throughout this range.

 

Example:

Spotted seatrout, also known as speckled trout, have been found in salinities ranging from 0.2 ppt to 75 ppt but studies estimate their ideal salinity being roughly 20 ppt. Favorable spawning temperatures range from 77 °F to 86 °F and favorable spawning salinity levels range from 17 to 35 ppt. Approximately 28 ppt is the ideal salinity for their eggs and larvae to survive. They move throughout their home range during the year, typically spending the summers close to the Gulf in higher salinity waters and spending the winters in the upper estuary in lower salinity waters.

 

Sunrise/ Moonrise/ Sunset/ Moonset

Every fisherman knows that the best fishing times are when the fish are feeding. Fish tend to feed during the sunrise, moonrise, just before sunset and the hour or so after, and during the set of the moon. It’s just a matter of knowing ahead of time exactly when the sun and moon will rise and set.

 

Moon Phase

Moon phase is the shape of the directly sunlit portion of the moon as it is viewed from the earth. This is measured by the moon’s position in its cycle and the percent illumination. The moon has a very powerful impact on Earth in many ways. For example, it creates and regulates tidal cycles by which many marine organisms survive. Some people think that specific lunar phases, such as a new moon or full moon, cause fish to be more active while others think it has more to do with the moonrise and moonset. One thing we do know is that full moons and new moons result in *spring tides and that can affect how brackish and inshore species act. Everyone knows there is a good chance that the lunar cycle has an impact on fishing, but there is no certainty as to how.

 

Additional info

Studies done on moon effects on fish behavior have shown how factors such as fish spawning, migration, activity, and feeding may be linked to the lunar cycles. Some studies showed that more fish were caught around new moons and full moons than at other times. These studies were based on the experience of expert anglers such as professional fishing guides.

*Spring tide is a tide just after a new or full moon, when there is the greatest difference between high and low water.

 

Altimetry

Altimetry is the altitude of the ocean or sea surface height and is measured in centimeters (cm). This tells us if there are high spots or low spots in the ocean surface column. High spots, called downwelling zones, are not good for fishing and are associated with positive values. Low spots are called upwelling zones and are better for fishing. Upwelling zones are associated with negative values. Transitional areas are shown by neutral values and are neither good nor bad for fishing. You should judge these values based on other conditions.

 

Additional info

Click here to view a map of updated altimetry-derived products in the Gulf of Mexico.

Altimetry data can be one of the most important conditions to consider, especially when fishing offshore for *pelagic fish. The value is a radar-based satellite product, meaning that its measurement is not affected by cloud cover.  Downwellings are usually associated with nutrient-poor waters and upwellings are nutrient-rich areas, ideal for attracting food for pelagic fish and other predators at the top of the food chain. Transitional areas are many times found between upwelling and downwelling zones and can form “oceanic highways” for species you might be targeting.

*Pelagic fish inhabit the water column (not near the bottom or the shore) of coasts, open oceans, and lakes.

Salinity

Salinity is the concentration of salt in water and is measured in practical salinity units (psu) or parts per thousand (ppt). The numeric difference between psu and ppt is small as these values are nearly equivalent. It’s beneficial to know what salinity levels your target species are known to inhabit. The salinity of the open ocean and the Gulf of Mexico averages about 35 ppt; inshore brackish waters of coastal Louisiana range from almost 0 ppt to almost 35 ppt and can change with tide, weather, and other factors.

 

Additional info

Stenohaline: marine organism that can only tolerate a narrow range of salinity.

Euryhaline: marine organism that can tolerate a wide range of salinities.

 

SST (Sea Surface Temperature)

SST is the skin temperature of the ocean surface water and is measured in degrees Fahrenheit (°F).

This factor can cause an increase or decrease in the activity level of fish and can influence feeding. Because fish are unable to regulate their body temperature, they are influenced by the surrounding temperature. If water is warm, there is generally an increase in fish movement as their metabolism accelerates and feeding increases. If water is cooler, fish tend to be inactive and become lethargic.

 

Additional info

Water depth is a major factor influencing water temperature. Heat comes from the sun and therefore, water tends to be warmer near the surface and cooler with increasing depth. Much discussion of how water temperature influences fish behavior centers on the surface and the immediate area underneath. However, currents bring water of differing temperatures together, called oceanic fronts, and these areas can have intense fish activity. The sudden temperature changes in these areas encourage plankton growth which attracts fish who feed on plankton or other fish that consume it.

Air Temperature

Air temperature is a measure of how hot or cold the air is and is measured in degrees Fahrenheit (°F).

Because fish are very sensitive to passing fronts and pressure changes, they have very good senses about the weather. Good fishing conditions tend to be during the weather ahead of a cold front due to lower pressure. Fish will often increase their activity in the days before the cold front moves in. 

 

Additional info

After a cold front passes and for a few days after, fishing conditions will remain poor due to the high pressure that follows. Fish tend to be lethargic during this time and are less likely to feed as frequently. Warm fronts can also be ideal fishing conditions. Lower pressure and weaker winds will bring fish closer to the surface and liven them up for swimming longer distances.

 

Wind Speed & Direction

Wind speed describes how fast the air is moving past a certain point and is measured in knots (kn). Wind direction describes the direction from which the wind comes from and is measured by the direction on a compass. Both can have a large impact on your fishing. There is an old saying that states, “Wind from the West, fish bite the best. Wind from the East, fish bite the least. Wind from the North do not go forth. Wind from the South blows bait in their mouth,” which is mostly true. The wind can also stir up the food chain and provide more cover from the sun due to wave action. It’s beneficial to know these variables because it is better to fish in a position where your bait moves with the wind, similar to other food in the water.

 

Additional info

Reference: 1 mph = 0.87 knots

 

Wind Gust

A wind gust is a brief increase in wind speed and measured in knots (kn).

Wind gusts occur essentially anytime the wind is blowing but they more noticeable when the speed of wind increases. It is unknown as to whether wind gusts specifically affect fish/fishing but see additional info for what causes wind gusts and why they occur.

               

Additional info

Wind gusts occur because air is not able to move along the ground at an even rate. Vegetation, land, elevation changes cause surface friction that can slow the wind in some places more than others. Air that is closer to the ground is more influenced by friction than higher up air, creating more turbulent winds along the ground and this is when you experience wind gusts.

               

Atmospheric Pressure (barometric pressure)

Atmospheric pressure is the weight or mass of an entire air column on a unit of surface area at sea level and is measured in inches of liquid mercury (inHg). Fish are affected by atmospheric pressure because they sense pressure changes through their air bladders. At a stable high pressure, fish are more comfortable and tend to actively feed throughout most of the water column. When pressure drops before a storm system, fish can sense the high pressure beginning to dissipate and they respond with a change in their feeding patterns. Fish tend to feed heavily right before this pressure drop.

 

Additional info

When evaluating your pressure, it’s better to assess the reading’s trends instead of focusing on the actual number reading. A reading of 30 inHg is considered normal; a steadily falling reading usually signals an approaching storm; and a rising reading usually signals clearing weather.

Fish that have large air bladders sense when pressure is dropping due to there being less pressure squeezing their bladder. This causes their air bladders to expand making fish uncomfortable and tend to move deeper in the water column to relieve the discomfort. Note that fish with small air bladders aren’t as affected by pressure changes as much as those with large air bladders. However, forage fish that they feed on also have air bladders and that could impact on where you might find fish.

 

Pressure Tendency

Pressure tendency is the character and amount of atmospheric pressure change during a specified period of time and is measured in millibars (mb). The speed at which air pressure increases or decreases can determine what type of weather you can expect, which can in turn help you make decisions about when to go fishing. Refer to Atmospheric Pressure.

 

Dew point

Dew point is the temperature at which condensation begins and is measured in degrees Fahrenheit (°F). Knowing the dew point can help you predict the probability of rain or fog, which can help you decide when you want to fish. Dew point tells us how much moisture the air is able to hold and if the air temperature drops below this value, the water vapor has to condense out of the atmosphere in the form of precipitation or fog. When fishing during a light rain, it allows you to cast your line more discreetly. During a light rain or immediately following one, insects are more likely to be out near the water surface potentially bringing fish closer to the surface as well.

 

Visibility

Visibility is a measure of the horizontal opacity of the atmosphere at the point of observation and is expressed in terms of the distance at which a person is able to see and identify a prominent dark object against the sky at the horizon. Visibility is measured in nautical miles (nmi). Our ability to see color and detail at a distant can be impacted by several factors such as air pollution or fog. It is unknown how or whether fog affects fish or not; however, it does cut down light penetration which can limit your visibility to locate the fish. Thick fog can also affect your ability to navigate your boat easily through waters.

 

Additional info

1 nautical mile = 1.1508 miles

 

Current

Currents are continuous and directed movements of water, measured in knots (kn) and by the direction on a compass in which they are flowing. Many factors drive currents such as winds, water density, and tides. Fish prefer to conserve energy and therefore, will usually not fight to swim against the current. Because of this, fish tend to swim with the current or they will stay in *eddies or behind structures to stay out of the current’s flow. When you are fishing in currents, you should cast up-current so that the presentation of your bait flows naturally.

 

Additional info

                *Eddies are small whirlpools that are caused by the circular movement of water.

 

Tide

Tide is the rise and fall in sea level resulting from the gravitational attraction of the moon and sun. Tide level is measured in feet (ft). Generally, the best time to fish is during a moving tide, when the water is in movement. High tides and low tides are the worst times to fish because water is not moving, and fish are less likely to feed.

               

Additional info

A falling or outgoing tide occurs when the tide is changing from high tide to low tide. It’s common for game fish to take advantage of outgoing tides to feed on the smaller bait fish being pushed out to sea. A rising or incoming tide occurs when the tide changes from low tide to high tide. When the tide is flowing in, fish move into the estuaries and search for food in places such as tidal flats.

SOURCES

 

Speckled trout example intro sources: (USM Gulf Coast research) (ASMFC)

Sunrise/moonrise/sunset/moonset sources: (Old Farmer's Almanac)

Moon phase sources: (Karl's Bait & Tackle ) (Peer reviewed journal)

Altimetry sources: (20echo)

Salinity sources: (NOAA) (NOAA)

SST sources: (NOAA) (Fish Research)

Air temperature sources: (AccuWeather)z

Wind speed & direction sources: (Environmental monitor) (SIERRA)

Wind gust sources: (theweatherprediction)

Atmospheric pressure sources: (The Weather Channel) (Arkansas Stripers)

Pressure tendency sources: (NOAA)

Dew point sources: (Decoded science) (AccuWeather)

Visibility sources: (NOAA) (NPS)

Current sources: (NOAA) (Sport Fishing Magazine)

Tide level sources: (NOAA) (Fishing Sun) (Cast away anglers club)

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