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Wildlife Science

Fish Science

Habitat Science

Lead Scientists: Robert Pacunski
  Dayv Lowry
Ecoregion: Puget Trough

Picture of juvenile Yelloweye Rockfish
Juvenile Yelloweye Rockfish

  Map of ROV survey locations
  Picture of ROV
SeaEye Falcon ROV
  Picture of ROV
ROV with cover removed

Marine Fish Monitoring

Population Assessment of Puget Sound Bottomfish Using a Small ROV

Project Description

Puget Sound is home to a diverse range of fishes that live on or near the bottom, generally referred to as groundfish or bottomfish, which includes species groups such as flatfish, rockfish, greenling, cod, and sculpins.  Due to current and historic commercial and recreational exploitation of many of these species, effective and timely management actions are required to ensure continued species diversity and sustainability.  Rockfish in particular were once a popular target of recreational fishers in Puget Sound, but continued declines in their numbers since the 1970s forced the Washington Department of Fish and Wildlife (WDFW) to prohibit fishing for rockfish in Puget Sound in 2010.  Also in 2010 the National Oceanic and Atmospheric Administration (NOAA) listed yelloweye and canary rockfish as "Threatened" species and bocaccio as an "Endangered" species under the provisions of the Endangered Species Act.  The conservation and recovery of rockfish and other bottomfish in Puget Sound ultimately depends on accurate species distribution and abundance estimates in order for fishery scientists to provide the best possible advice to fishery managers.

Since 1987 the WDFW has conducted regular trawl surveys to assess Puget Sound bottomfish populations, but this technique is not practical in the rocky habitats and areas of high-relief inhabited by many species, including rockfish, lingcod, cabezon, and kelp greenling.  Scuba-diving can be used to survey untrawlable habitats but is limited to depths of 100 feet or less, which only encompasses a portion of many species' depth distributions.  Because of these limitations, population estimates for bottomfish in untrawlable areas have been either imprecise or unavailable, making effective management of these species problematic and leading WDFW marine fish scientists to explore the development of new survey methods to obtain this vital information.

In 2004, WDFW began using a small remotely-operated vehicle (ROV) to conduct quantitative visual surveys of bottomfish inhabiting high-relief seafloor habitats.  Unlike trawling, which can damage habitat and result in fish mortality, the ROV is generally non-destructive and non-lethal.  The ROV is easily deployed from a small research vessel and can be operated at depths up to 1,000 feet and in all seafloor habitats.  ROV video data can be used to produce precise population estimates for the most commonly encountered species and allows WDFW scientists to describe and quantify the relationships between fish and their preferred habitats.   Analysis of ROV video data has also revealed the locations of many pieces of derelict fishing gear, which has been used to facilitate their removal from Puget Sound waters.  Since 2004, WDFW has conducted four ROV surveys in the San Juan Islands and completed a year-long survey in April 2013 that encompassed all of Puget Sound.  WDFW staff are currently reviewing ROV video collected during the most recent survey, and the results should be available to managers by November 2014.

New tools have recently been added to the ROV that will enhance future surveys:  a high-definition camera to improve the ability to detect and identify many of the small and cryptic fishes, and a conductivity-temperature-depth (CTD) meter to collect data in real-time that will be used to examine linkages between physiochemical water quality parameters and fish distribution/abundance.  These tools, in combination with advanced spatial analysis techniques, will allow WDFW scientists to expand their understanding of the ecosystem and improve the management of Puget Sound bottomfish populations.
Watch the ROV survey the depths of Puget Sound in this video clip:



  • Jim Beam
  • Jen Blaine
  • Andrea Hennings
  • Lisa Hillier
  • Erin Wright

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