Event Title

Rockfish surveys in the Strait of Juan De Fuca and Puget Sound 2005-2017

Presentation Abstract

Since the early 1980s, biologists from the Seattle Aquarium have been informally monitoring bottom fish on rocky reefs in Neah Bay, Washington. These observations have produced an intimate knowledge of these reefs, and an informal record of abundance and distribution. Based on increasing concern over the long term stability of bottom fish populations in this area by both state and federal agencies, the aquarium formalized monitoring in 2005 with diver based video surveys to quantify bottom fish (rockfish and lingcod) diversity and abundance over time. Divers performed 100 m video transects devised to be non-invasive and repeatable for assessing diurnally active and sessile bottom fishes over time. Four transects were conducted each year in August from 2005-2015 at four permanently marked sites with a fifth site added in 2010. Surveys were all 100 m long and were surveyed in both the forward and reverse direction to gather information about fish disturbance or attraction to divers and gear. Species were qualified and quantified by biologists counting fish off of the archived video on large screen monitors. Statistical difference between numbers of fish observed during forward vs. reverse passes of surveys was not significant. Thus only fish counted on the forward transect pass were included for further statistical analyses. Over thirteen years there was an increase in diversity of adult rockfish and a decrease in density of adult schooling rockfish such as blacks and blues. There were several significant young of the year (YOY) rockfish recruitment “jackpot recruitment” events that occurred in 2006, 2008, 2011, 2012, 2014 and 2106. Numbers of adult and YOY rockfish densities were not significantly correlated with any environmental variables measures such as sea surface temperature (SST) and chlorophyll. This study may elucidate trends in rockfish diversity and abundance to advise management plans for rockfish conservation.

Session Title

Recovery and Monitoring for ESA-listed Rockfish and Habitats in the Salish Sea

Conference Track

SSE11: Species and Food Webs

Conference Name

Salish Sea Ecosystem Conference (Seattle, WA : 2018)

Document Type

Event

SSEC Identifier

SSE11-17

Start Date

4-4-2018 3:45 PM

End Date

4-4-2018 4:00 PM

Type of Presentation

Oral

Contributing Repository

Digital content made available by University Archives, Heritage Resources, Western Libraries, Western Washington University.

Geographic Coverage

Salish Sea (B.C. and Wash.)

Rights

This resource is displayed for educational purposes only and may be subject to U.S. and international copyright laws. For more information about rights or obtaining copies of this resource, please contact University Archives, Heritage Resources, Western Libraries, Western Washington University, Bellingham, WA 98225-9103, USA (360-650-7534; heritage.resources@wwu.edu) and refer to the collection name and identifier. Any materials cited must be attributed to the Salish Sea Ecosystem Conference Records, University Archives, Heritage Resources, Western Libraries, Western Washington University.

Type

text

Language

English

Format

application/pdf

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Apr 4th, 3:45 PM Apr 4th, 4:00 PM

Rockfish surveys in the Strait of Juan De Fuca and Puget Sound 2005-2017

Since the early 1980s, biologists from the Seattle Aquarium have been informally monitoring bottom fish on rocky reefs in Neah Bay, Washington. These observations have produced an intimate knowledge of these reefs, and an informal record of abundance and distribution. Based on increasing concern over the long term stability of bottom fish populations in this area by both state and federal agencies, the aquarium formalized monitoring in 2005 with diver based video surveys to quantify bottom fish (rockfish and lingcod) diversity and abundance over time. Divers performed 100 m video transects devised to be non-invasive and repeatable for assessing diurnally active and sessile bottom fishes over time. Four transects were conducted each year in August from 2005-2015 at four permanently marked sites with a fifth site added in 2010. Surveys were all 100 m long and were surveyed in both the forward and reverse direction to gather information about fish disturbance or attraction to divers and gear. Species were qualified and quantified by biologists counting fish off of the archived video on large screen monitors. Statistical difference between numbers of fish observed during forward vs. reverse passes of surveys was not significant. Thus only fish counted on the forward transect pass were included for further statistical analyses. Over thirteen years there was an increase in diversity of adult rockfish and a decrease in density of adult schooling rockfish such as blacks and blues. There were several significant young of the year (YOY) rockfish recruitment “jackpot recruitment” events that occurred in 2006, 2008, 2011, 2012, 2014 and 2106. Numbers of adult and YOY rockfish densities were not significantly correlated with any environmental variables measures such as sea surface temperature (SST) and chlorophyll. This study may elucidate trends in rockfish diversity and abundance to advise management plans for rockfish conservation.