CRED Towed-Diver Fish Biomass Surveys at Howland Island, Pacific Remote Island Areas in 2008

Description

Towed-diver surveys (aka. Towboard surveys) are conducted by the Coral Reef Ecosystem Division (CRED) of the NOAA Pacific Islands Fisheries Science Center (PIFSC) as part of biennial Pacific Reef Assessment and Monitoring Program (RAMP) Cruises. These cruises support NOAA Coral Reef Conservation Program (CRCP) long-term goals for sustainable management and conservation of coral reef ecosystems. 9 towboard surveys (23.7238 km in length), were conducted at Howland Island in the Pacific Remote Island Areas from 24 January - 14 February 2008 as part of RAMP Cruise HI0801. Towboard surveys are a good method for obtaining a general description of large reef areas, assessing the status of low-density populations of large-bodied reef fish, large-scale disturbances (e.g., bleaching), general distribution and abundance patterns of macro-invertebrates (e.g., COT, giant clams), and for assessing trends in these populations and metrics. A pair of scuba divers (1 fish and 1 benthic diver) are towed 60 m behind a small survey launch at a speed of 1-2 knots and a depth of approximately 15m. Each survey is 50 min long, covers about 2 km of habitat, and is divided into ten 5-minute survey segments. The fish diver records, to the lowest possible taxon, all large-bodied reef fishes (>50cmTL) seen within 5m either side and 10m in front of the towboard. Length of each individual is estimated to the nearest cm. The fish towboard is also outfitted with a forward-facing digital video camera to record the survey swath. The benthic diver records percent cover of coral and macroalgae, estimates benthic habitat type and complexity, and censuses a suite of benthic macroinvertebrates including Crown of Thorns sea stars and sea urchins. The benthic towboard is equipped with a downward-facing digital still camera which images the benthos at 15 second intervals. These images are analyzed for percent cover of coral, algae, and other benthic components. Both towboards are equipped with SEABIRD SBE-39 temperature/depth sensors set to record at 5 second intervals. Latitude and longitude of each survey track is recorded at 15 second intervals using a Global Positioning System (GPS) receiver onboard the tow boat. A layback algorithm is applied to more accurately map the position of the divers with respect to the reef environment. This algorithm calculates the position of the divers based on the position of the tow boat taking into account the length of the tow rope, the depth of the divers, and the curvature of the survey track. This metadata applies to the fish biomass observations.

Resources

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Tags

  • reef fishes
  • united states of america
  • reef monitoring and assessment
  • coral reef
  • marine ecosystem
  • corals
  • the united states
  • biosphere
  • pacific remote island areas
  • oceans
  • towed diver surveys
  • pacific reef assessment and monitoring program (pacific ramp): biennial monitoring for the u.s. paci
  • numeric data sets
  • biology
  • howland island
  • earth science
  • pria
  • reef fish census
  • benthic habitats
  • howland island (00s176w0001)
  • central pacific ocean
  • usa minor outlying islands
  • coral reef ecology
  • ocean basin
  • reef assessment and monitoring program (ramp)
  • coastal processes
  • 1221
  • zoology
  • coral reefs
  • coris_metadata
  • pacific ocean
  • hi0801
  • country/territory

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