The data set consists of two products. The first product are maps that represent fish average densities collected by active hydroacoustic survey technique in the water column along a transect for each monthly sample. These data are also compiled by location by year. The fish density data is plotted over a bathymetric map. The second product are Excel spreadsheets with a summary of the integration of fish echoes over a sampling period that is used to produce the first product by location.
The purpose for which these data were collected was to help find areas of high fish density within a coral reef environment. Other reasons to collect the data was to help locate reef fish spawning aggregation sites, obtain target strength values for different reef fish species and determine size frequency distribution of some of these species.
Currentness_Reference: Ground condition.
Maintenance_and_Update_Frequency: None planned
Bajo de Cico, Desecheo and Mona Islands, off West Coast of Puerto Rico. U.S. Virgin Islands.
Theme_Keyword: EARTH SCIENCE > Oceans > Marine Biology > Fish
Theme_Keyword_Thesaurus: ISO 19115 Topic Category
Place_Keyword_Thesaurus: CoRIS Place Thesaurus
OCEAN BASIN > Atlantic Ocean > Caribbean Sea /North Atlantic Ocean > Puerto Rico > Puerto Rico (18N066W0000)
COUNTRY/TERRITORY > United States of America > Puerto Rico > Puerto Rico (18N066W0000)
COUNTRY/TERRITORY > United States of America > Puerto Rico > Isla de Mona (18N067W0002)
OCEAN BASIN > Atlantic Ocean > Caribbean Sea /North Atlantic Ocean > Puerto Rico > Isla de Mona (18N067W0002)
COUNTRY/TERRITORY > United States of America > Puerto Rico > Isla de Desecheo (18N067W0007)
OCEAN BASIN > Atlantic Ocean > Caribbean Sea /North Atlantic Ocean > Puerto Rico > Isla de Desecheo (18N067W0007)
COUNTRY/TERRITORY > United States of America > U. S. Virgin Islands > U. S. Virgin Islands > U. S. Virgin Islands (17N064W0000)
OCEAN BASIN > Atlantic Ocean > Caribbean Sea > Virgin Islands > Lesser Antilles > U. S. Virgin Islands (17N064W0000)
Place_Keyword_Thesaurus: CoRIS Region
Use_Constraints: Please cite contributors when using this data.
Prior to the survey period, the hydroacoustic system used in this study was calibrated relative to a US Naval standard transducer of known sensitivity. Throughout the survey period, field calibrations utilizing a tungsten sphere standard target were accomplished. All water column echoes selected were assumed to be fish echoes based on the echo grouping pattern and target strength. If doubtful about the echo characteristics, then the echo signal tracking across the split beam transducer quadrats record was studied to help determine if such an echo was generated by a fish, since such tracking between transducer quadrats indicates echo movement. Echo movement is a strong indicator of a fish echo, although not the only option. Also, echo target strength was a second variable considered to determine if the signal was likely to be a fish echo. Echo target strength usually correlates with size of object being detected. Preliminary echo data editing permits the selection of echo regions and target strengths. This enables the investigator to eliminate echoes due to ocean surface and bottom return and other signals caused by reflective interference. All collected acoustic data was recorded to a digital tape ensuring that the sampled record is available for future re-examination if need be.
During data analysis echo target strength in dB can be used as a data selector. One can also filter echo data by geographical position, depth or time stamp. Echo signal transducer beam incidence angle can also be used to filter and select data. These search strategies enables the exclusion of undesired echo values for the sought analysis. Most of these echo data analyses will be done using Microsoft's Access database software or similar software such as Excel.
The fish hydroacoustic survey data is only for ocean continental shelf drop-off areas of 40-100m in depth, although most of the data is between 50-90m depth. The main collection location is Bajo de Cico, a submerged bank off the West coast of Puerto Rico. Additional collection areas are Desecheo and Mona Islands, also off the West coast of Puerto Rico, but the data collection is not as extensive as for Bajo de Cico. The USVI were also sampled, but only one time.
A split-beam hydroacoustic system (Model 244, Hydroacoustic Technology Incorporated, Seattle, WA) operating at 120 kHz (Transducer Model 541S) with a 6o beam was used for the hydroacoustic survey(HAS). Data were recorded to computer and DAT tape (Sony Model PCM-M1) during field collection, utilizing HTI's DEP data acquisition program and later analyzed using ECHOSCAPE, an HTI data entry and analysis program and Microsoft Access, a database analysis program. The transducer was oriented straight down in the water column and mounted on a 1m long aluminum dead-weight towing vehicle. The transducer was usually towed from a davit or cleat on the starboard side gunwale of the vessel at amid-ship or just aft of amid-ship position to ensure pitching movement stability. The transducer lateral distance from the vessel hull was usually 1m and the transducer depth was 1-2m. The maximum sampling depth was approximately 100 m. The hydroacoustic system collected the data files directly to a laptop computer. All data were also concurrently recorded to DAT tape, providing an ultimate data backup of the unfiltered digital samples for later reprocessing as digital samples. Differential or WAAS-enabled (Wide Area Augmentation System) Global Positioning System (GPS) receivers (Garmin 76) were interfaced with all hydroacoustic systems to provide position to within approximately 3 m. The GPS receiver was connected to an external antenna which was positioned with a PVC pipe on the transducer davit and oriented to be directly over the transducer. During 2009, the GPS positioning data was obtained from a ComNav Marine, Ltd (Richmond, British Columbia, Canada) Model Navigator G4 to provide position to within approximately 1m. All school density data were successfully collected within 4 days following the full moon for both Puerto Rico and the USVI. Surveys in the USVI consisted of a series of predetermined transects following the continental shelf break area and the region just inshore of this break. Survey transects generally zigzagged along the edge of the continental shelf break approximately 50 m deep. Transects were traversed at a boat speed of approximately 4-5 knots. In the USVI, the overall acoustic repetition (ping) rate of the hydroacoustic system was 2 pings/sec. One minute echo integration sampling intervals were used to define the minimum spatial areas of resolution over which to estimate school biomass during field data collection at Bajo de Cico, Puerto Rico in order to replicate 2002 sampling instrument parameters used in a previous project. This strategy would ensure data comparison compatibility. A 12 second interval (.2 minute) interval was used to collect the USVI data. Once the data was collected, a backup of all files written to the laptop and track files stored in the GPS was accomplished to a portable hard disk. The DAT tapes were archived inside a cardboard box after verifying it was labeled correctly.
Process_Date: Not complete
Geographic_Coordinate_Units: Decimal Degrees
Horizontal_Datum_Name: North American Datum of 1983
Ellipsoid_Name: Geodetic Reference System 80
All HTI output files are in ASCII format, and can be easily edited and imported into most spreadsheet and database programs. A combination of six different types of output files can be selected; *.RAW,*.ECH,*.FSH,*.SUM,*.INT,*.BOT. RAW files have unaltered individual echo data. ECH files contain only those echoes that make up the individual tracked fish. FSH files have records of all tracked fish which met the fish tracking criteria for the sample period. SUM files summarize sample time and total tracked fish. INT files estimates fish density, or biomass based on the mean of the squared voltage of the echo returns from fish over a set spaced interval. BOT files provide the GPS positioning data to the individual echoes and the bottom depth. ECHOSCAPE is the HTI program that permits you to visualize the collected data on the computer screen as a water column perspective for post processing. Once a *.RAW file is opened by ECHOSCAPE the program stores the data as a *.mdb file. The *.mdb file can be analyzed using Microsoft Access database program. Copy of the Access data columns can be imported into EXCEL and other spreadsheet programs for further analysis and graphing. The main fields of the most used file (RAW) are: Ping number, Range to target (in meters), Amplitude of target echo (in volts), Pulse width at 1/2, 1/4, and 1/8, amplitude points (in digital samples), Target angle off-axis in the "left/right" plane, target angle off-axis in the "up/down" plane, Bottom (in meters), Overall beam pattern factor, Target strength (in dB), Tracked fish number, Transducer mux channel number, Sequence number and Sample period number.
Entity_and_Attribute_Detail_Citation: Hydroacoustic Technology Incorporated, Seattle, WA
These hydroacoustic data are water column echo data and have not been screened for absolute accuracy. NOAA cannot be held liable for use of these data in a manner other than for perusal of preliminary hydroacoustic data for scientific research on coral reefs ecosystems. Disclaimer - NOAA makes no warranty regarding these data, expressed or implied, nor does the fact of distribution constitute such a warranty. NOAA cannot assume liability for any damages caused by any errors or omissions in these data, nor as a result of the failure of these data to function on a particular system.
Please contact the distributor .
Data Format Name: *.RAW,*.ECH,*.FSH,*.SUM,*.INT,*.BOT also *.MDB and *.XML. DAT tape data is being converted to *.SMP files but task is not complete.