Jose A. Rivera, under contract to; NOAA Fisheries, Southeast Fisheries Science Center, Miami Laboratory, Miami, FL., Unpublished material, Hydroacoustic Biomass Assessment of Reef Fish Spawning Aggregations in Western Puerto Rico (CRCP ID# 1242-05/06/07)..
Horizontal positions are specified in geographic coordinates, that is, latitude and longitude. Latitudes are given to the nearest .01. Longitudes are given to the nearest .01. Latitude and longitude values are specified in Decimal Degrees.
The horizontal datum used is North American Datum of 1983.
The ellipsoid used is Geodetic Reference System 80.
The semi-major axis of the ellipsoid used is 6378137.
The flattening of the ellipsoid used is 1/298.257.
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.
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.
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.
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.
Are there legal restrictions on access or use of the data?
- Access_Constraints: None.
- Use_Constraints: Please cite contributors when using this data.
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.
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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. Fees None