A clear guide to fishing and oceanographic terms you'll encounter in FishRadar and the angling world. Each definition is practical and rooted in how these conditions affect fish behavior and your catch.
A safety feature that uses GPS to detect if your boat is drifting beyond a set radius, then sends a critical alert to wake you if you've anchored to rest while fishing. Useful in strong currents or overnight anchoring.
The maximum number of fish of a given species you're legally allowed to catch and keep in a single day. Regulations vary by region, season, and water type. FishRadar's regulations feature shows bag limits for your location.
The weight of air pressing down on the water surface. Fish are sensitive to pressure changes; falling pressure (storm approaching) typically increases feeding activity, while rising pressure (clearing weather) can suppress it. FishRadar forecasts pressure trends to pinpoint bite windows.
The underwater topography — depth contours, drop-offs, ridges, valleys, and seafloor structure. Fish congregate on structure (depth changes, hard bottom, vegetation). FishRadar's maps show bathymetric detail worldwide, and detailed regions can be downloaded for offline use.
A forecast time period when conditions (solunar phase, pressure, temperature, current speed) align to maximize fish feeding activity. FishRadar calculates bite windows hourly and sends push alerts (Pro/Captain) when conditions optimize.
The period when fish are actively feeding and willing to strike bait or lures. Fish bite at specific times tied to solunar phases, tides, barometric pressure, and water temperature. Predicting bite windows is FishRadar's core function.
A green pigment in phytoplankton (tiny marine plants). High chlorophyll means abundant food; fish congregate where productivity is high. Satellite sensors measure surface chlorophyll in milligrams per cubic meter (mg/m³). FishRadar uses chlorophyll as a key condition signal.
The directional movement of water caused by tides, wind, or underwater features. Fish prefer moderate currents (0.1–0.5 m/s) where food drifts to them without exhausting effort. Strong currents can push fish into slack-water refuges. FishRadar measures and forecasts current speed and direction from satellite and model data.
A steep change in water depth, like a continental shelf edge or underwater cliff. Fish stage on drop-offs to ambush prey moving between shallow and deep water. Drop-offs are visible on bathymetric maps and scored higher by FishRadar's algorithm.
A circular ocean current that forms behind an obstacle (island, headland, submarine mountain) or where two currents collide. Eddies trap nutrient-rich water and concentrate fish. FishRadar detects eddies from satellite currents and flags them as high-potential zones.
A coastal area where a river meets the ocean, mixing fresh and salt water. Estuaries are breeding grounds and nurseries for many fish species. Tidal exchange and nutrient influx make estuaries highly productive. FishRadar identifies estuaries and weights them as likely good fishing zones.
The distance wind travels over open water, which determines wave height and roughness. High fetch means large, rough waves; low fetch means calm conditions. Fish behavior varies: some species bite better in calm water, others in churned water where prey is displaced.
A visible line in the water where two water masses of different temperatures meet. Thermal fronts concentrate plankton and small fish, attracting larger predators. Satellite sea-surface temperature (SST) imagery reveals fronts. FishRadar detects and scores thermal fronts as high-opportunity zones.
The pattern of a fish's movement (cruising, foraging, resting). Fish gaits change with water temperature and season. Warmer water energizes fish; cold water slows them. FishRadar's temperature-based scoring indirectly factors fish gait through SST thresholds.
A pair of latitude and longitude values (e.g., 41.20°N, 29.10°E) that pinpoint a location on Earth. FishRadar scores any coordinate 0–100 and returns a detailed forecast, making GPS your entry point to the app.
The physical and biological environment a fish species requires: depth, structure, temperature, food availability, light. Fish seek specific habitats. FishRadar's multi-signal scoring recreates habitat preferences algorithmically.
A sudden emergence of aquatic insects (mayflies, caddisflies) from the water, usually tied to temperature and daylight. Hatches trigger intense feeding. Predicting hatches requires knowing insect life cycles and local water temperatures. FishRadar's temperature forecasts are a starting point.
The position of the moon (new, waxing, full, waning) in its monthly cycle. Solunar theory predicts that new and full moons create peak feeding periods (major feeding times). FishRadar calculates exact moon phase and forecasts solunar activity.
A tide with the smallest range (lowest high tide, highest low tide) occurring when the sun and moon are at a 90-degree angle. Neap tides create weak water movement and can result in slower fishing. Opposite of spring tide.
Microscopic marine plants (diatoms, dinoflagellates) that form the base of the ocean food web. High phytoplankton density is detected via chlorophyll satellite measurements and indicates productive fishing grounds. FishRadar uses satellite chlorophyll as a productivity signal.
Tiny organisms (plant and animal) drifting in water. Fish feed on zooplankton; zooplankton feed on phytoplankton. Areas rich in plankton attract fish. Satellite chlorophyll provides a proxy for phytoplankton presence.
The change in barometric pressure over time: falling (low pressure system approaching), stable, or rising (high pressure, clearing). Fish often bite more aggressively when pressure is falling. FishRadar tracks pressure trends in hourly forecasts.
The concentration of dissolved salt in water, measured in parts per thousand (ppt). Freshwater is 0 ppt; seawater is ~35 ppt. Fish have salinity preferences (euryhaline fish tolerate wide ranges; stenohaline fish are salt or freshwater specialists). Estuaries have variable salinity.
The degree to which a gas (oxygen, carbon dioxide) is dissolved in water. Low dissolved oxygen (hypoxia) creates dead zones where fish cannot survive. FishRadar factors oxygen availability into habitat scoring where data is available.
A hypothesis that fish feeding peaks occur at specific times tied to the position of the moon and sun relative to the angler's location. "Major" feeding times occur when the moon is directly overhead or underfoot; "minor" times occur at 90-degree angles. FishRadar calculates solunar theory and forecasts bite windows.
A period of 20–30 minutes at the turn of the tide (between flood and ebb) when tidal current is near zero. Fish behavior changes during slack tide: some species bite better; others suspend. FishRadar forecasts tidal slack periods as secondary bite windows.
A fishing regulation specifying that you may keep fish within a certain size range (e.g., 14–18 inches) but must release fish smaller or larger. Slot limits protect breeding stock. FishRadar's regulations reference includes slot limits for your region.
A specific time (major or minor) when solunar theory predicts elevated fish activity. The two major solunar times per day align with the moon's transit overhead and underfoot; minor times are 6 hours offset. FishRadar calculates exact solunar times and alerts you to bite windows.
A tide with the largest range (highest high tide, lowest low tide) occurring when the sun and moon are aligned (new or full moon). Spring tides create strong water movement and often result in excellent fishing. Opposite of neap tide.
The temperature of the top layer of ocean or lake water, measured in degrees Celsius or Fahrenheit. Fish are ectothermic and sensitive to temperature. Each species has an optimal temperature range. FishRadar sources SST from satellite (MODIS) and models, with seasonal thresholds per region.
A distinct layer in the water column where temperature drops rapidly with depth. Fish often congregate at the thermocline because it concentrates food and provides comfort. Identifying the thermocline requires depth and temperature data; FishRadar scores areas with likely thermoclines based on depth and seasonal SST.
An instrument that measures water temperature. Traditional anglers use submersible thermometers; modern apps use satellite and model data. FishRadar provides hourly SST (surface temperature) and historical seasonal patterns.
The rise and fall of water level caused by the moon's and sun's gravitational pull. Tides create currents that move water, expose and hide structure, and trigger feeding. FishRadar forecasts tide times and heights, with solunar corrections for optimal bite windows.
The difference between high and low tide water level at a given location. Large tidal range means strong tidal currents and exposed/submerged structure; small range (neap tide) means weaker currents. FishRadar shows tidal range in hourly forecasts.
A feature that lets you see how conditions were on a past date or will be on a future date, and what your chosen spot would have scored then. Useful for planning trips or analyzing past successful days. FishRadar Captain tier includes time-travel re-scoring.
A process where deep, nutrient-rich water rises to the surface, usually caused by wind pushing surface water offshore or colliding currents. Upwelling creates highly productive fishing grounds (e.g., Peru Current, California Current). FishRadar detects upwelling signatures in chlorophyll and current data.
The warmth of the water, measured in °C or °F. Fish activity, metabolism, and location are temperature-dependent. Warm water speeds digestion; cold water slows it. FishRadar tracks SST as a primary scoring signal and forecasts temperature trends.
The vertical distance from wave trough to crest, measured in meters or feet. Calm water (small waves) favors sight-feeders; rough water (large waves) favors ambush predators and can dislodge prey, triggering feeding frenzies. FishRadar forecasts wave height in hourly conditions.
Atmospheric conditions including wind, pressure, precipitation, cloud cover, and visibility. Weather affects surface wave height, water temperature (via heating/cooling), and fish behavior (barometric pressure drops often trigger feeding). FishRadar integrates weather forecasts into condition scores.
Air movement measured in direction (cardinal compass) and speed (km/h, knots, m/s). Wind drives surface currents and creates waves. Light wind (ideal <15 km/h) keeps water calm and reduces fatigue; heavy wind creates rough conditions and can limit boat safety. FishRadar forecasts wind speed and direction hourly.
Tiny animal organisms (copepods, larval fish, krill) that drift in water and feed on phytoplankton. Fish feed on zooplankton. High phytoplankton density (detected via chlorophyll satellite) supports abundant zooplankton, creating a productive food web. FishRadar's chlorophyll signal indirectly indicates zooplankton abundance.