Event Title
Relative Abundance of Sixgill Sharks (Hexanchus griseus) in Elliott Bay, Seattle, Washington
Presentation Abstract
The Sixgill Shark Research Project is designed to address gaps in the body of scientific knowledge on bluntnose sixgill sharks (Hexanchus griseus) in Puget Sound. This project utilizes three interwoven techniques: (1) genetics research, (2) visual marker tagging, and (3) video analysis. Seattle Aquarium biologists monitor sixgill shark sightings reported by local divers (since 1999) and study their relative abundance in Elliott Bay under the Aquarium’s pier (since 2003). Here we report on our findings of relative abundance.
Bluntnose sixgills are a species of conservation concern. Sixgills are listed as “near threatened” on the IUCN Red List. Living mainly at abyssal depths but also in the shallow waters of the Salish Sea, sixgills are thought to be long-lived and slow-growing, and appear to have established movement corridors and home ranges that remain relatively fixed over time. As apex predators they are important members of marine communities; and, owing to their life history characteristics such as a slow rate of maturity and low reproductive rates, are thought to be extremely vulnerable to exploitation.
Here we present our findings of relative abundance of sixgill sharks in Elliot Bay during the two time periods that the research was conducted: 2003-2005 and 2008-2015. We present the number of individual sharks seen each night, number of sharks tagged, number of returning tagged sharks, sex ratios, estimated number of sixgills residing in Elliott Bay (using capture-mark-recapture techniques), and seasonal and long-term trends in abundance.
Session Title
General species and food webs
Conference Track
Species and Food Webs
Conference Name
Salish Sea Ecosystem Conference (2016 : Vancouver, B.C.)
Document Type
Event
Start Date
2016 12:00 AM
End Date
2016 12:00 AM
Location
2016SSEC
Type of Presentation
Poster
Genre/Form
conference proceedings; presentations (communicative events); posters
Contributing Repository
Digital content made available by University Archives, Heritage Resources, Western Libraries, Western Washington University.
Subjects – Topical (LCSH)
Hexanchus--Counting--Washington (State)--Elliott Bay; Hexanchus--Washington (State)--Elliott Bay--Genetics
Geographic Coverage
Elliott Bay (Wash.); 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
Relative Abundance of Sixgill Sharks (Hexanchus griseus) in Elliott Bay, Seattle, Washington
2016SSEC
The Sixgill Shark Research Project is designed to address gaps in the body of scientific knowledge on bluntnose sixgill sharks (Hexanchus griseus) in Puget Sound. This project utilizes three interwoven techniques: (1) genetics research, (2) visual marker tagging, and (3) video analysis. Seattle Aquarium biologists monitor sixgill shark sightings reported by local divers (since 1999) and study their relative abundance in Elliott Bay under the Aquarium’s pier (since 2003). Here we report on our findings of relative abundance.
Bluntnose sixgills are a species of conservation concern. Sixgills are listed as “near threatened” on the IUCN Red List. Living mainly at abyssal depths but also in the shallow waters of the Salish Sea, sixgills are thought to be long-lived and slow-growing, and appear to have established movement corridors and home ranges that remain relatively fixed over time. As apex predators they are important members of marine communities; and, owing to their life history characteristics such as a slow rate of maturity and low reproductive rates, are thought to be extremely vulnerable to exploitation.
Here we present our findings of relative abundance of sixgill sharks in Elliot Bay during the two time periods that the research was conducted: 2003-2005 and 2008-2015. We present the number of individual sharks seen each night, number of sharks tagged, number of returning tagged sharks, sex ratios, estimated number of sixgills residing in Elliott Bay (using capture-mark-recapture techniques), and seasonal and long-term trends in abundance.
