Facilitation of rockfish by octopus in the Salish Sea
Presentation Abstract
Octopuses are generalist predators that feed by biting or tearing into prey, or by boring a small hole through the prey’s exoskeleton and injecting a cocktail of paralytic and digestive enzymes. These modes of feeding lead to leakage of prey tissues into the surrounding waters. Scavengers may be attracted to these clouds of prey tissue, or the remnant shells left by the octopuses in midden piles. Because octopuses tend to bring prey back to permanent den sites to feed, these dens could become relatively constant attraction points for scavengers. In the San Juan Archipelago, shrimp, especially Pandalus danae, are likely scavengers, and are also the preferred prey of copper rockfish (Sebastes caurinus). We used time-lapse photography to monitor occupied and unoccupied giant Pacific octopus (Enteroctopus dofleini) dens for evidence of rockfish responding to the presence of octopuses. Occupied dens had significantly higher copper rockfish abundance than unoccupied dens. Occupied dens appeared to host resident rockfish, as the same individuals were routinely observed resting in or near occupied dens. While rockfish and other demersal predatory fishes were occasionally observed at unoccupied dens, fish here were more transient, with the exception of small schools of Puget Sound rockfish (S. emphaeus) and one lingcod. If octopuses facilitate rockfish by attracting prey species, ecosystem-based management of rockfish in the Salish Sea could include the protection of octopuses, such as with the recently adopted octopus protection areas in Puget Sound.
Session Title
Session S-10E: Evaluation, Conservation and Restoration of Species Associated with High-Relief, Rocky Habitat in the Salish Sea
Conference Track
Species and Food Webs
Conference Name
Salish Sea Ecosystem Conference (2014 : Seattle, Wash.)
Document Type
Event
Start Date
2-5-2014 1:30 PM
End Date
2-5-2014 3:00 PM
Location
Room 613-614
Genre/Form
conference proceedings; presentations (communicative events)
Contributing Repository
Digital content made available by University Archives, Heritage Resources, Western Libraries, Western Washington University.
Subjects – Topical (LCSH)
North Pacific giant octopus--Salish Sea (B.C. and Wash.); Copper rockfish--Salish Sea (B.C. and Wash.)
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
Facilitation of rockfish by octopus in the Salish Sea
Room 613-614
Octopuses are generalist predators that feed by biting or tearing into prey, or by boring a small hole through the prey’s exoskeleton and injecting a cocktail of paralytic and digestive enzymes. These modes of feeding lead to leakage of prey tissues into the surrounding waters. Scavengers may be attracted to these clouds of prey tissue, or the remnant shells left by the octopuses in midden piles. Because octopuses tend to bring prey back to permanent den sites to feed, these dens could become relatively constant attraction points for scavengers. In the San Juan Archipelago, shrimp, especially Pandalus danae, are likely scavengers, and are also the preferred prey of copper rockfish (Sebastes caurinus). We used time-lapse photography to monitor occupied and unoccupied giant Pacific octopus (Enteroctopus dofleini) dens for evidence of rockfish responding to the presence of octopuses. Occupied dens had significantly higher copper rockfish abundance than unoccupied dens. Occupied dens appeared to host resident rockfish, as the same individuals were routinely observed resting in or near occupied dens. While rockfish and other demersal predatory fishes were occasionally observed at unoccupied dens, fish here were more transient, with the exception of small schools of Puget Sound rockfish (S. emphaeus) and one lingcod. If octopuses facilitate rockfish by attracting prey species, ecosystem-based management of rockfish in the Salish Sea could include the protection of octopuses, such as with the recently adopted octopus protection areas in Puget Sound.
