Observed impacts of derelict fishing nets on rocky reef habitats and associated species in Puget Sound
Presentation Abstract
Over 4,500 derelict fishing nets have been removed from Puget Sound since 2002. These derelict fishing nets cause harm to marine habitats and species. Nets are often found draped over rocky reef habitat and kelp, causing sedimentation, smothering habitat and cutting off access to valuable habitat for marine species. In Hood Canal, derelict nets were found draped across centuries-old cloud sponge (Aphrocallistes vastus) reefs, the reef scraped bare beneath. The 4,597 nets removed as of December 31, 2013 were degrading over 600 acres of marine habitats comprised of: mud; boulders on sand, mud and gravel; aquatic vegetation; and low and high relief rocky substrate. Approximately 44% or 2,027 of removed derelict nets were encountered in rocky reef habitats. Previous monitoring of derelict net removal sites showed that the habitats degraded by derelict fishing nets recovered within a single growing season after removal operations. Additional qualitative observations from derelict gear removal divers note the recovery of rocky habitats, such as those at Lawson Reef and South Lopez Island, with abundant fish and other sessile animals moving into the areas after derelict fishing gear removal. Animals become entangled and injured in the derelict nets and, unable to escape, perish. These animals attract scavengers, which become entangled as well. Sometimes, derelict nets stay suspended in the water column or are draped over reefs. Smaller fish hide behind the nets, attracting predators such as birds and fish, which become entangled and die in the nets. Of the 263 unique species observed in removed derelict fishing nets, 77% (203 species) have been found in rocky reef habitats, illustrating the importance of these habitats for multiple species. Using a catch rate model developed by researchers at UC Davis using our data, we can estimate the annual catch rate of these nets based on the animals found in them. We estimate that the 2,027 nets removed from rocky habitats were entangling 395 mammals, 10,445 birds, 41,143 fish, and 1,366,692 invertebrates annually each year the nets were derelict. While many species were have been found in derelict nets removed from a variety of habitats, some species of animals were observed more frequently in nets encountered in rocky habitats. Examples include: northern abalone, Haliotis kamtschatkana; Puget Sound king crab, Lopholithodes mandtii; greenling, Hexagrammos decagrammus or Hexagrammos sp.; lingcod, Ophiodon elongatus; and rockfish, Sebastes sp. or Scorpaenidae sp. Derelict fishing nets in rocky habitats have significant impacts on species associated with these habitats. For example, we can estimate that nets removed from rocky habitats were entangling 4,317 rockfish every year they were derelict.
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)
Fishing nets--Environmental aspects--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
Observed impacts of derelict fishing nets on rocky reef habitats and associated species in Puget Sound
Room 613-614
Over 4,500 derelict fishing nets have been removed from Puget Sound since 2002. These derelict fishing nets cause harm to marine habitats and species. Nets are often found draped over rocky reef habitat and kelp, causing sedimentation, smothering habitat and cutting off access to valuable habitat for marine species. In Hood Canal, derelict nets were found draped across centuries-old cloud sponge (Aphrocallistes vastus) reefs, the reef scraped bare beneath. The 4,597 nets removed as of December 31, 2013 were degrading over 600 acres of marine habitats comprised of: mud; boulders on sand, mud and gravel; aquatic vegetation; and low and high relief rocky substrate. Approximately 44% or 2,027 of removed derelict nets were encountered in rocky reef habitats. Previous monitoring of derelict net removal sites showed that the habitats degraded by derelict fishing nets recovered within a single growing season after removal operations. Additional qualitative observations from derelict gear removal divers note the recovery of rocky habitats, such as those at Lawson Reef and South Lopez Island, with abundant fish and other sessile animals moving into the areas after derelict fishing gear removal. Animals become entangled and injured in the derelict nets and, unable to escape, perish. These animals attract scavengers, which become entangled as well. Sometimes, derelict nets stay suspended in the water column or are draped over reefs. Smaller fish hide behind the nets, attracting predators such as birds and fish, which become entangled and die in the nets. Of the 263 unique species observed in removed derelict fishing nets, 77% (203 species) have been found in rocky reef habitats, illustrating the importance of these habitats for multiple species. Using a catch rate model developed by researchers at UC Davis using our data, we can estimate the annual catch rate of these nets based on the animals found in them. We estimate that the 2,027 nets removed from rocky habitats were entangling 395 mammals, 10,445 birds, 41,143 fish, and 1,366,692 invertebrates annually each year the nets were derelict. While many species were have been found in derelict nets removed from a variety of habitats, some species of animals were observed more frequently in nets encountered in rocky habitats. Examples include: northern abalone, Haliotis kamtschatkana; Puget Sound king crab, Lopholithodes mandtii; greenling, Hexagrammos decagrammus or Hexagrammos sp.; lingcod, Ophiodon elongatus; and rockfish, Sebastes sp. or Scorpaenidae sp. Derelict fishing nets in rocky habitats have significant impacts on species associated with these habitats. For example, we can estimate that nets removed from rocky habitats were entangling 4,317 rockfish every year they were derelict.
