benthic trawl studies in the south sound: 1987 vs. 2014/2015
TRANSCRIPT
• Interagency program • Open-water disposal sites • Evaluation procedures
• Disposal site monitoring
Anderson/Ketron Disposal Site
Non-dispersive
Established in 1989
360-480 feet deep
Relatively few biological resources
Dredged material stays on-site
A/K site now within the Reserve boundaries, though allowed under
management plan
DMMP determined additional monitoring important for future
disposal decisions
Disposal site
! Disposal site selection process included a benthic trawl study in 1987 ! Repeat the study using the same methodology ! Again focus on invertebrate species of potential “commercial and sport concern”
1. Evaluate biological resources in vicinity of site for any important changes since 1987
2. Compare invertebrate community at on-site stations to off-site stations
3. Compare on-site Dungeness crab and Pandalid shrimp densities to commercially viable thresholds used in 1987
Same 30 stations as 1987
PLUS
8 additional on-site stations
July 1987
October 1987
February 1987
May 1987
July 2015
October 2015
February 2016
May 2016
Water depth (a)
Distance behind vessel (b)
Beam trawl
Placeholder for video file
Crab Pandalid Shrimp Sea Cucumbers
Sea Stars “Other”
• Crabs • Dungeness (Cancer magister) • Red rock (C. productus) • Graceful (C. gracilis) • Tanner crab (Chionoecetes bairdi)
• Pandalid shrimp • Spot prawn (Pandalus platyceros) • Dock shrimp (P. danae) • Pink shrimp (P. jordani and P. eous)
• Sea cucumber • Giant California sea cucumber
(Parastichopus californicus) • “Other” invertebrates
• Including other genera of shrimp and crabs
Nearly 50 species of (mostly) demersal fish Most common: ◦ Blackbelly eelpout ◦ Roughback sculpin ◦ Plainfin midshipman
Many different flatfish
NO endangered species
CO Sole Pygmy poachers
Blackbelly eelpouts
Cancer gracilis
Cancer productus
Cancer gracilis
Cancer productus
Relative abundance of
“rock crab” species by depth
• 85% graceful rock crab (Cancer gracilis)
• C. gracilis too small for harvest
July 2014
0
1
2
3
4
0 20 40 60 80 100 120 140 160 180 200
No.
Obs
erve
d
CW (mm)
Cancer magister Dungeness crab
0
1
2
3
4
5
6
0 20 40 60 80 100 120 140 160 180
CW (mm)
Cancer productus Red rock crab
Male Female
0
2
4
6
8
10
12
14
16
18
0 20 40 60 80 100 120 140 160 180
CW (mm)
Cancer gracilis Graceful crab
Mostly pink shrimp
on-site
February 2015
dock shrimp
coonstripe shrimp
pink shrimp
The disposal site is at this depth
spot prawn
February 2015
Biological Resource (Full Study Area)
Objective 1: Observed Change from
1987 to 2014-2015
CANCER CRAB
Dungeness Crab 2.5 times greater numbers in 2014-2015
Combined “Rock Crab” (C. productus and C. gracilis) Much more abundant in 2014-2015
Red Rock Crab (C. productus only)
Approximately 10 times more abundant in 2014-2015
PANDALID SHRIMPRecreational Pandalid Shrimp
(excluding Pink Shrimp) Much more abundant in 2014-2015
Pink Shrimp Much more abundant in 2014-2015
ECHINODERMS
Sea Cucumbers Only half the number in 2014-2015
Sea Stars Roughly equal numbers in both surveys
Biological Resource
Objective 2: Difference between On-Site
Stations and Off-Site Stations in 2014-2015?
Mean #/hectare over all seasons
On-Site Off-Site Dungeness Crab 1.1 9.4
Combined “Rock Crab” (C. productus and C. gracilis) 154.8 448.5
Pandalid Shrimp (all species) 834.1 5,154.6 Sea Cucumbers 0 88.9
Sea Stars 12.1 263.2
Biological Resource
Objective 3: On-site Density Exceeds the 1987 Commercial/Recreational Viability
Threshold?
CANCER CRABDungeness Crab No
Combined “Rock Crab” (C. productus and C. gracilis) No
Red Rock Crab (C. productus only) No
PANDALID SHRIMP
Recreational Pandalid Shrimp (excluding Pink Shrimp) No
Pink Shrimp Yes; but unlikely commercially viable according to WDFW
ECHINODERMSSea Cucumbers No
Chris Hunt NewFields Jasper Boas NewFields Charlie Eaton BioMarine Tom Putnam BioMarine Don Rothaus WDFW Don Velasquez WDFW George Peterson WDFW Mark O'Toole WDFW Laura Inouye Ecology Tom Gries Ecology
Celia Barton DNR Jamie Kligo DNR Betty Bookheim DNR Dawn Swanstrom DNR Birdie Davenport DNR David Fox USACE Lauran Warner USACE Kelsey van der Elst USACE Madelyn Martinez USACE Heather Fourie USACE Greg Jensen UW Shandra O'Haleck NMFS Erika Hoffman EPA Justine Barton EPA
http://www.nws.usace.army.mil/Missions/Civil-Works/Dredging/
Full report available:
Celia Barton [email protected]
Lauran Warner [email protected]