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Layer: SEAMAP_Reef_Fish_Effort_by_10SQGrid (ID: 0)

Name: SEAMAP_Reef_Fish_Effort_by_10SQGrid

Display Field: GRIDID

Type: Feature Layer

Geometry Type: esriGeometryPolygon

Description: Fishery independent catch data from annual Southeast Area Monitoring and Assessment Program (SEAMAP) Reef Fish Surveys (1995 to 2017) are used to map the distribution of sampling effort. The primary objective of the survey is to provide indices of the relative abundances of fish species associated with topographic features (natural reefs, banks and ledges) located on the continental shelf of the Gulf of Mexico in from Brownsville, Texas to the Dry Tortugas, Florida. The total reef area surveyed is approximately 1771 square km; 1244 square km in the eastern and 527 square km in the western Gulf.The offshore reef fish survey was initiated in 1992, with sampling conducted during the months of May to August from 1992-1997, 2001-2002, and 2004 through present. Due to budget constraints, no surveys were conducted from 1998 to 2000 and in 2003. The 2001 survey was abbreviated due to ship scheduling, and only completed sampling in the western Gulf of Mexico. The survey area is large. Therefore, a two-stage sampling design is used to minimize travel times between sample stations. The first-stage or primary sampling units (PSUs) are blocks 10 minutes of latitude by 10 minutes of longitude. The first-stage units are selected by stratified random sampling. The blocks are stratified, with strata defined by geographic region (4 regions: South Florida, Northeast Gulf, Louisiana-Texas Shelf, and South Texas), and by reef habitat area (Blocks = 20 square km of reef, Blocks > 20 square km of reef). There are a total of 7 strata. The ultimate sample sites (second stage units) within a block are selected randomly. However, stratum 1 (South Florida, small blocks) and stratum 7 (south Texas, small blocks) are not consistently sampled.The SEAMAP Reef Fish Survey has employed several camcorders in underwater housings since 1992. Sony VX2000 DCR digital camcorders mounted in Gates PD150M underwater housings were used between 2002 and 2005, and Sony PD170 camcorders between 2006 and 2007. In 2008, the survey started using a stereo camera system. This was assembled at the NMFS Mississippi Laboratories Stennis Space Center Facility, and consists of a digital stereo still camera head, a digital video camera, CPU, hard drive and connectors mounted in an aluminum housing. The stereo cameras are mounted orthogonally and a height of 50 cm above the bottom of the pod. A chevron fish trap with 1.5-inch vinyl-clad mesh is used to capture fish for biological samples. The camera pod is baited with squid.One video tape from each station is selected out of the four for viewing. If all four video cameras face reef fish habitat and are in focus, the viewed tape is selected randomly. Tape viewers examine 20 minutes of the selected video tape, identify, and enumerate all species for the duration of the tape. Identifications are made to the lowest taxonomic level. In 1992, each fish was counted every time it came into view over the entire record time. The total of all these counts was the Maximum Count. From 1993-2007, the time when each fish entered and left the field of view was recorded. This is referred as a time in - time out procedure (TITO). From these data, the Minimum Count was calculated. The Minimum Count is the maximum number of a taxa in the field of view at one instance. The 1992 video tapes were destroyed during Hurricane Katrina and cannot be reviewed. The 2008 digital data are not viewed using the TITO procedure. The digital video viewing records the frame number or time stamp of the image where the maximum number of a fish taxon occurs along with the number of the fish taxon in the image. Both the TITO and current viewing procedure result in the Minimum Count estimator of relative abundance. Minimum Count prevents counting the same fish more than once. Videos are viewed from the time when the view clears from any silt plume raised by the gear when it landed. Less than 20 minutes may be viewed if the duration when water is not clear enough to count fish is less than 20 minutes, or if the camera array is dragged. If a tape contains a large amount of fish, it is sub-sampled. There are four cases for sub-sampling: 1) when there is generally a large number of fish of a given species present throughout the tape so that following individual fish is difficult; 2) large number of fish occur in pulses periodically during the tape; 3) a single school of fish; and, 4) multiple schools of fish.SEAMAP Reef Fish Survey catch and effort data from 1995 to 2017 were extracted for analysis. Effort (number of camera sets) is summarized by 10 minute longitude by latitude blocks in which sampling occurred. The final summary is represented as a 10 minute longitude by latitude polygon layer. The layer attributes include the central longitude (LON_GRIDC) and latitude (LAT_GRIDC), a polygon identifier (GRIDID) and the number of video camera sets (N) for each 10 minute longitude by latitude block in which at least one set was made.

Copyright Text: David Hanisko, Research Fisheries Biologist, National Marine Fisheries Service, Jeff Rester, SEAMAP Coordinator, Gulf States Marine Fisheries Commission, Adam Pollack, Fisheries Biologist III, Riverside Technology, Inc. National Marine Fisheries Service

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