Step 4 – Eliminate areas outside preferred temperature range
Now take your updated chart and use the Chesapeake Bay Temperature map provided and the temperature information found on the following links to begin shading out areas that are outside avoidance level temperatures for your target fish using the information you gathered in Step 1.
- Temperature Pattern Stability (Eyes on the Bay) - General temperature patterns will remain stable unless there are prolonged periods of substantial rain (cools water) or extreme heat (warms water).
- If the preferred temperature range for your target fish is cooler than existing surface water, look for the coolest water available.
- Fish down-tide of underwater grass beds - During warmer months, in nearshore areas, waters near underwater grass beds are often cooler than surrounding waters due to the shading effects from the underwater grasses.
- Fish deeper during the day - During warmer months, in deeper waters, the coolest water is often found at deeper depths.
- Fish surface waters near deeper waters at night - During the summer, surface waters often cool 3 to 4 F⁰ overnight. Surface waters are coolest just prior to sunrise.
- Fish downwind nearshore areas at night – cool surface waters will get stacked up on the downwind shore providing large, cool water areas containing abundant food for forage fish, forage fish and hungry predator fish.
- If the preferred temperature range for your target fish is warmer than existing surface waters, look for the warmest water available.
- Fish deeper areas protected from current - During cooler months in deeper waters, the warmest water is often found at deeper depths. Several types of bay fish will overwinter in these areas if there is adequate protection from current.
- Fish surface waters near deeper waters in mid-afternoon - During the winter, surface waters often rise 3 to 4 F⁰ during the day. Surface waters are warmest during the mid-afternoon. Shallow, dark bottom creeks near deeper water will also warm quickly and attract gamefish.
- Fish downwind nearshore areas in mid-afternoon – warm surface waters will get stacked up on the downwind shore providing large, warmer water areas containing abundant food for forage fish, forage fish and hungry predator fish.
- Fish near warm-water discharges - During cooler months in nearshore areas, waters near warm-water discharges often draw Bay fish.
- An event called the "Striped Bass Squeeze" occurs in the summer when rockfish (striped bass) try to move to deeper water in search of cooler water, but are prevented by poorly oxygenated waters. Striped basevent up being squeezed into a small layer of barely suitable water at the extremes of their maximum suitable temperature (84°F) and their minimum dissolved oxygen requirements (~3 mg/L.)
- Note: For your convenience, we have included temperature information for some popular Bay gamefish.
- Chesapeake Bay Temperature map (Eyes on the Bay) – (view in Step 4 on main page) This composite map includes temperature data over all Maryland Bay waters from surface to bottom and will provide a good overview of general temperature conditions.
- Current vs. historical temperature comparison (Eyes on the Bay) –
This site will help you determine if the surface water is much warmer or colder than normal in your general fishing area. When water temperatures are warm, cooler than normal temperatures may increase activity of gamefish. When water temperatures are cool, warmer than normal temperatures may also increase gamefish activity.
- 'Water Temperature by Depth' Map (Eyes on the Bay) –
This site will help you identify where to find the depth of the best water temperature (and adequate oxygen levels) for your target fish. During warmer months, the deeper waters will often be cooler than surface waters. During the cooler months, the deeper waters will often be warmer than surface waters. In shallower locations and deeper locations during spring and fall turnovers, the water temperature will often be uniform from surface to bottom. So depending on the conditions and time of year, your target fish may move up or down, or may even be able to move throughout the entire water column to find their preferred water temperature.
If you click a station on the map, a plot of water temperature and oxygen by depth will appear. This feature will help you determine the depth where major changes in water temperature occur, as well as where oxygen is most available. Fish in water depths with preferential temperature for your target fish species, but where oxygen levels are above 3 mg/L.
||Surface water temp = Max Fishing Depth water temp
||Water column is well mixed, water temperature is uniform from surface waters down to maximum fishing depth or DO NOT FISH BELOW THIS DEPTH layer.
||Surface water temp warmer than Max Fishing Depth water temp
||Surface waters are at least 2°F warmer than water temperatures at maximum fishing depth or DO NOT FISH BELOW THIS DEPTH layer. Note: These cooler, oxygenated, deeper waters can be key locations during warmer months.
||Surface water temp colder than Max Fishing Depth water temp
|| Surface waters are at least 2°F cooler than water temperatures at maximum fishing depth or DO NOT FISH BELOW THIS DEPTH layer. Note: These warmer, oxygenated, deeper waters can be key locations during cooler months.
- Temperature monitoring stations (Eyes on the Bay) –
This site will help you determine the specific temperature at the stations nearest to your general fishing area.
- Use the "Filter station" dropdown to select continuous monitoring, long-term monitoring, and/or partners/other data providers.
- The long-term monitoring sites ( red squares) are generally located in deep water and can be selected and will show you how current year temperature conditions compare to the long-term average.
- The continuous monitoring sites ( orange and light green circles) are generally located in shallow waters and show oxygen conditions at real, or near real time. Because these sites collect data every 15 minutes you are able to see the temperature changes that occur in response to local rainfall (cools water) or shallow, poorly flushed areas (warms water). Temperature data can be plotted numerous ways.
- The Partners/Other Data Providers sites ( orange and yellow crosses) are additional sites that show water temperature conditions at real or near real time. Because these sites collect data every 15 minutes you are able to see the rapid temperature changes that occur in response to local rainfall (cools water) or shallow, poorly flushed areas (warms water).
- Temperature monitoring buoys (Chesapeake Bay Observing System [NOAA CBOS]) –
This real-time site will help you verify your temperature conditions at several mainbay/main river sites. Select the station nearest to your general fishing location, and select "Water Temperature." For convenience, you can plot out temperature information from 1 to 30 day periods.
Now that you have eliminated areas that are outside avoidance level temperatures of your target fish on your chart, you are ready to move to: Step 5 – Eliminate areas with poor water clarity