FLOE Field Programs


In December, 2000, the NOAA Fish Lidar went to Tampa, Florida to look for schooling fish in the shallow waters off the east coast of Florida. On the left is a photograph of a school of mullet that was taken from the aircraft. We made several passes over this school. The echo grams are two consecutive passes over the same school from different directions. In the photograph, the school looks darker than the surrounding water. The lidar clearly shows the fish as a region of enhanced reflection.

In this experiment, the lidar measured a number of schools. A small boat equipped with a scientific echosounder was directed to each school and made acoustic measurements. In all, seven schools were captured both by the lidar and by the echosounder. More schools were targeted by the lidar, but it proved impossible to get the boat to most of these to obtain the acoustic measurements. The correlation between lidar and acoustics for the seven schools was almost perfect (99.6%). There was also a professional fish spotter on the plane with us. He was able to identify the species of the schools very reliably from the air.

James H. Churnside, David A. Demer, and Behzad Mahmoudi, A comparison of lidar and echosounder measurements of fish, ICES Journal of Marine Science, 60: 147 154. 2003.

Alaska 2000

The NOAA lidar FLOE has flown along with a digital camera in the waters off of southern Alaska in the summer of 2000. This is program is funded by the North Pacific Marine Research Initiative. The Principal Investigator is Dr. Evelyn Brown of the Institute of Marine Science of the University of Alaska at Fairbanks.

We evaluated airborne remote sensing, using lidar and color digital video, in the North Pacific in 2000. Specific objectives were (1) to determine lidar depth-penetration range, (2) to develop ocean color indices as a proxy for depth penetration and Chl a, (3) to compare lidar with acoustic and net-sampling data, (4) to define diurnal variability over large areas, and (5) to evaluate strengths and weaknesses. Depth penetration ranged from 18 to 50 m in non-silty water, with lowest values observed inshore by day and highest values on the continental shelf at night. A green index, derived from the three- band video data, was significantly related to depth penetration and was in general agreement with SeaWiFS satellite Chl a values. Significant correlations with acoustic data were obtained in an area with a high concentration of capelin, Mallotus villosus.

Evelyn D. Brown, James H. Churnside, Richard L. Collins, Tim Veenstra, James J. Wilson, and Kevin Abnett, Remote sensing of capelin and other biological features in the North Pacific using lidar and video technology, ICES Journal of Marine Science, 59: 000 000. 2002.
FLOE image of rising fish school


In August and September of 1999, the FLOE flew on the Spanish Casa aircraft as part of the European project on Experimental Surveys for the Assessment of Juveniles (JUVESU).  Flights were made off of the northwest coast of Spain and in the Bay of Biscay.  The map below shows the relative distribution of fish (in segments of about 1 nautical mile) off of the west coast of Spain seen during one evening flight.  The plot is a histogram of the depths of the fish densities.  These show a strong concentration of fish within the bay (Ria de Vigo) that is mostly between 5 and 10 m.  There is also a band of fish offshore that is mostly between 5 and 25 m in depth.

Typical "echogram" images are presented below.  The one on the left is about 1 nautical mile of data taken offshore during midday of Julian day 243.  Several small, dense schools are seen.  The other is an image taken in the evening of the same day in the same area. The schools are larger, but more diffuse in the evening than at midday.  High-resolution images can be downloaded by clicking on left image or right image.

The map below is a typical map from the Bay of Biscay.  A larger area was flown on this day, and one can see patches of fish distributed throughout the survey area.  The depth distribution shows a peak in the 5 - 10 m bin with fish detected down to about 30 m.

California Squid 1999

In January 1999, ETL and the State of California Department of Fish and Game conducted an experiment with FLOE in California to see if we could detect squid. FLOE was reinstalled on the King Air and we flew around the southern California coast. The squid were plentiful as were the squid fishermen.

The following images are graphs of data. The X axis is time in seconds and the Y axis is depth in meters. The laser fires 30 shots per second. There are 60 seconds worth of data plotted, so these graphs represent 1800 shots from the laser. The aircraft we used was flying at about 75 m/s (meters per second), so 60 seconds represents about 4.5 Km in distance. To learn more about FLOE's hardware, go to the Instrument Page.

You may click on the image to see a slightly bigger image(800x600) or if you click the link you will get a high resolution image(2400x1800). The high resolution images will show the full detail of the data and will print out very nice.

Image1 - 1/11/99, 21:49 PST, 34 degrees 3 minutes N, 119 degrees 0 minutes W. The thick line at about 25 m is the bottom. The lighter areas above the bottom at 10-15 and at 50-55 s are squid. For a high resolution image, click here. Image2 - 1/11/99, 21:07 PST, 33 degrees 55 minutes N, 119 degrees 59 minutes W. There is a group of squid at 10 -12 s that is a few m from the bottom. A much larger group is at 30-35 s, and extends up to 10 m below the surface.  For a high resolution image, click here.
Image3 - 1/12/99, 19:47 PST, 33 degrees 54 minutes N, 119 degrees 58 minutes W. The group here, at around 30 s, is clearly separated from the bottom. The bottom just under the school is at 50 m. For a high resolution image, Click here. Image 4 - 1/12/99, 19:40 PST, 33 degrees 53 minutes N, 120 degrees 00 minutes W. The main group here is at 30-33 s, and extends from about 10 to 20 m above the bottom. There is a second group at about 37 s that is just a little higher. Above both groups is a plankton layer. For a high resolution image, Click here.


In August and September of 1998, the FLOE flew on the Spanish Casa aircraft as part of the European project on Experimental Surveys for the Assessment of Juveniles (JUVESU).  Flights were made off of the northwest coast of Spain, off of the west coast of Portugal, and in the Bay of Biscay.

The "echogram" images below show typical data from these flights.  The first is an image of a number of small schools of sardines in just off of the west coast of Galicia in Spain.  Time relates to distance by the aircraft speed, which was about 150 kts, or 75 m/sec.  The second image is of a much larger school off of the west coast of Portugal.  Clicking on the image brings up a larger image on the screen.  To see the full detail, click on small schools or large school to bring up the full resolution.  This can be printed out with full resolution.

We can also obtain calibrated distributions of fish in depth and by location.  As an example, the following plot shows the depth distribution for one particular flight.  Each horizontal line represents an integral over a 5-m depth bin and an average over 30 seconds of flight (about 2 km).   We can see that the fish were generally located between 20 and 40 m in depth.

Washington State Herring Survey

We found out that the Washington State Department of Fish and Wildlife was going to do a herring survey in May, so we contacted Norm Lemberg, Steve Burton and Mark Otoole and arranged to fly FLOE over their survey operations. Later we would compare data to see how the different survey methods worked.During the day and evening of May 5, 1997 we collected lidar data over the Puget Sound off of the western coast of Washington State using FLOE in the Cessna. In addition to the lidar there was an acoustic survey ship below that was from the State of Washington Department of Fish and Wildlife also mapping the area for herring. They would chart the acoustic signal and if they detected fish, would trawl and sample them. We overflew the same area and will compare the lidar data with the acoustic data. Because the water of Puget Sound is so turbid, the lidar can only see about 15 meters (50 feet) deep. In clear water we can usually see to 40 meters (130 feet) deep. The trawl ship found the biggest concentration of fish along the 48 degree North, 50.5 minute latitude track. The fish were at between 22 to 27 fathoms (132 to 162 feet). Below is a map of the transects that the ship traversed (Heavy Black Lines) and where we flew (lighter black lines). The red spots over the black lines are where we detected fish schools.

California 1997

Lidar Results

The maps below show some of the processed data for the flight of April 6. The first map shows the flight track and fish schools that were located along the track. The black line is our flight track according to the Global Positioning System (GPS). The red squares indicate fish schools. The second map shows the beam attenuation coefficient of the lidar for the same flight track. Attenuation coefficient is a measure of how clear the water is. Smaller spots indicate the water is more clear and bigger spots indicate the water is less clear. The third map is a plot of the ship track of the David Starr Jordan. The Jordan collected "egg pump" data for the days of April 5 and 6. Egg pump data are where seawater is pumped through a set of filters and then the fish eggs are counted. In this case anchovy eggs were counted.

102 101

Here are some examples of the processed data from these flights. In the following graphs, the Y axis is depth. The 0 line is the ocean's surface. There is a blank section from the surface to 5 meters deep. We don't look for fish in this region because of the laser pulse reflection from the surface. The X axis is time. There are 30 shots of the laser in one second, so 30 seconds represents 900 laser shots of data. In the data field, darker tint indicates a stronger return signal. Click on any graph to get a larger more detailed graph (800x600). If you want high resolution graphs that show all of the detail and are suitable for publication, click on the High Resolution link below the graph. These files are 2400x1800. They display much bigger than the screen, but will print out very nicely and can be saved using the File and Save As commands in your browser. Hit your back button to return.

In the first graph there are two distinct schools of fish with the suggestion of a third. They range from about 7-8 meters deep to about 22 to 23 meters flight speed was about 75 meters per second. (~140 Kts). The fish schools cover about 7 seconds worth of data which gives total fish school length of about 525 meters. For a graph of 800x 600 click on the picture. For a high resolution graph, 2400x1800, click here. The second graph shows a group of dolphins.  For a high resolution graph, deep. Our 2400x1800, click here.
The third graph shows a school of anchovy. For a high resolution graph, 2400x1800,  click here. The fourth graph shows what a layer of plankton looks like. For a high resolution graph, 2400x1800, click  here.

Fish Lidar Cruise '95

The 1995 cruise was conducted off of the Southern California coast for three weeks during September 1995. The purpose of Cruise95 was to collect FLOE (Fish Lidar, Oceanic, Experimental) data, acoustic data, and in situ data from the water and then compare the performance of FLOE with the acoustic instruments. Acoustic instruments have been used for a number of years to detect fish schools.

The picture at the left shows the David Starr Jordan. At the right, the Fish Lidar optics package (arrow) is shown mounted on the flying bridge.

If you would like to know more about the system hardware, check out the Fish Lidar hardware page.



The picture on the right shows the sonar data for one of the schools of fish seen from the ship. The picture on the left is FLOE (lidar) data, collected at the same time. The vertical scales show depth in meters, and both data sets were acquired in one minute. The white blob on the right side of each picture is a school of fish. The left sides of each picture are a single ping for the acoustic and a single laser pulse from FLOE. It takes 600 laser pulses to give us one minute of data. While the details are different because the two instruments are not looking at exactly the same part of the school, the general features are very similar.