Great South Channel Habitat Management Area Analysis

Size: px

Start display at page:

Download "Great South Channel Habitat Management Area Analysis"

Ross Shields
6 years ago
Views:

1 Great South Channel Habitat Management Area Analysis NEFMC Habitat Committee Meeting March 19, 2013 Salem, MA Note that this is the version presented at the meeting modified from version previously posted online

2 Committee tasking MOTION 5, (McKenzie, Alexander) from meeting Move that the Committee request the PDT develop an alternative for the Great South Channel proposed habitat management area consisting of a single area of roughly equivalent habitat protection value to the cumulative value of the four proposed sub-areas, as identified by SASI cluster/pdt analysis. (5/1/2)

3 Previous recommendations and motions 6/8/2011 PDT Recommends consideration of GSC for a habitat management area, specifically various areas to encompass gravel features; these areas are smaller than the Z LISA cluster 7/20/2011 The AP supports consideration of a closed area or gear restricted area in the Great South Channel; one recommendation was to use LISA cluster at 0.01 level 7/21/2011 Committee motion 9: (Goethel/Grout) Analyze possible gear restrictions, including no gear restrictions, in the four polygons identified in the Great South Channel on Map 8 (7/0/0)

4 Previous recommendations and motions 8/15/2011 PDT recommends a single area in GSC as either a closure or a gear modification area (the PDT did not intend the boxes to be directly used as management options; they were draft boundaries; PDT seeking guidance regarding goals to encompass certain amounts of habitat) 8/30/2011 The Committee reiterated support for the approach proposed in July: possible gear restrictions in the four polygons (each of the four areas separately and combined) identified in the Great South Channel on Map 8 of the July decision document. Combined was intended to mean analyzing the four separate boxes in combination, not that a large area be developed. 12/4/2012 The Committee revisited this issue and asked the PDT to develop a single HMA for the GSC that has equivalent habitat value to the four individual areas.

5 Goal of this Analysis Identify a single box in the GSC area that encompasses seafloor vulnerable to the adverse effects of fishing. The single box should have equivalent habitat value as the existing four boxes.

6 Selected Great South Channel (GSC) study area Study area selection necessary to compare original and new boxes* Encompasses original 4 adverse effects (AE) areas (in blue) Encompasses Nantucket Shoals Federal waters only * for example, X% of the Great South Channel is boulder cobble

Oceanography Miller et al 1998 The Great South Channel (GSC) is an undersea channel between shallower Nantucket

A fairly steady coastal current flows south along the east coast of Cape Cod s forearm and into the GSC.

flow along the northern flank of Georges Bank. Also, strong currents are driven by winds and tides.

7 Oceanography Miller et al 1998 The Great South Channel (GSC) is an undersea channel between shallower Nantucket Shoals and Georges Bank. A fairly steady coastal current flows south along the east coast of Cape Cod s forearm and into the GSC. Some of this coastal current flows south around Nantucket Shoals, while some turns east and joins the northeastward flow along the northern flank of Georges Bank. Also, strong currents are driven by winds and tides. Three LME persistent fronts are located in GSC. Right whale critical habitat area and shipping channel are prominent in the region. Valentine 2002 Woods Hole Oceanographic Institution Belkin 2009 Right Whale sitings BACKGROUND Belkin et al 2009

Fishing in GSC (2009) Scallop GC 2009 0 79 Scallop LA 2009 0 391 Trawl 2009 0 8211 These are

These images demonstrate approximately where fishing with adverse effects on the seafloor

8 Fishing in GSC (2009) Scallop GC Scallop LA Trawl These are realized Z outputs from the SASI model. See how different the scale ranges are. These images demonstrate approximately where fishing with adverse effects on the seafloor occurred in Lot s of scalloping between meters, GC boats in BACKGROUND shoaler water north of Nantucket.

There was a huge amount of rock and mud and sand at the end of the glacier, under it,

Outcrops in this area are most likely dominated by till deposits, not bedrock.

9 Substrate polarmet.osu.edu GSC was near the southernmost extent of the glaciers in the last ice age. There was a huge amount of rock and mud and sand at the end of the glacier, under it, and deposited as the glacier melted. Every conceivable grain size is represented. Outcrops in this area are most likely dominated by till deposits, not bedrock. On top of the glacial deposits are reworked glacial deposits, including sand dunes. BACKGROUND earthscience.bcsdk12.org Pratt & Schlee 1969 Bothner & Spiker 1980 Valentine 2002

10 Substrate This is a map focusing on the substrate types in GSC. This is the substrate model in SASI. These are Thiessen/Voronoi polygons, so there is one polygon for each data point. The smaller the polygon, the higher the data density. You ll be looking at this substrate data a lot. Do you have any questions? BACKGROUND

11 Clusters of Hard Bottom Thiessen polygon boundaries removed for ease of viewing This is based on Figure 6D from Harris & Stokesbury 2010 It shows spatial clustering of dominant grain sizes (Sd) High grain size relative to survey area mean Very high grain size relative to survey area mean BACKGROUND

12 Clusters of Hard Bottom This map highlights the largest areas of contiguous bouldercobble dominated seafloor Largest contiguous areas of cobble-boulder dominated seafloor BACKGROUND

13 Clusters of Hard Bottom LISA=local indicators of spatial association Shows where vulnerable seafloor is clustered How strong (significant) is the clustering P 0.01 very strong P 0.05 strong LISA cluster (p 0.05) LISA cluster (p 0.01) BACKGROUND

14 Original 4 Adverse Effects Areas LISA clusters only used to guide identification of GSC as an area with seafloor vulnerable to the adverse effects of fishing The original 4 AE areas correspond closely to both the Harris & Stokesbury analysis and the contiguity analysis Original AE areas Largest contiguous areas of cobble-boulder dominated seafloor Higher than average grain size Much higher than average grain size BACKGROUND

Each gear type is 50% transparent so you can see all 3.

15 Original 4 boxes raised the attention of GC and LA scallopers. The big map shows GC, LA, trawl fishing in 2009 (i.e. the corrected realized Z for 2009). Each gear type is 50% transparent so you can see all 3. Less fishing of that gear type More fishing of that gear type These are the images side-by-side: BACKGROUND LA GC Otter trawl Largest contiguous areas of b-c

16 The discussion with the scallopers at the last Committee meeting led to the motion to consider a single box option with equivalent habitat value as the four boxes.

Habitat Value of Original 4 AE areas bottom is the most vulnerable to the adverse effects of fishing Goal was to find an option that most closely matched the area cobble-boulder Used grain size

17 Habitat Value of Original 4 AE areas bottom is the most vulnerable to the adverse effects of fishing Goal was to find an option that most closely matched the area cobble-boulder Used grain size coverage of the existing 4 boxes Also looked at proportionality compared to entire GSC region GSC Region GSC 1 GSC 2 GSC 3 GSC 4 Sum GSC 1-4 Area in Sq. Nautical Miles (nm 2 ) , nm nm 2 = 4.8% 144 nm 2 =24.4% 132 nm 2 = 54.8% 590 nm 2 2,808 nm 2 Sand-Mud-Silt Granule-Pebble Boulder-Cobble METHODS

18 Single Box Options Hand drew boundaries Focusing on contiguous C-B bottom Did not use an optimization routine Too many irregular edges Regular edges limited to trapezoids, circles Many options, how to proceed? METHODS Largest contiguous areas of b-c

19 Prior to the Jan 2013 PDT meeting Bill and Jason Amaru provided a modification to northern-most box Three single-box options analyzed for January PDT meeting to explore the approach At the January PDT meeting Drew Minkiewicz provided a single box option and requested that single box options not extend beyond the 40 meter contour; polygon drawn by David Rudders, VIMS After the January meeting, I took the Rudders polygon and experimented with building out from it to achieve equivalent habitat protection; stayed within meter contour; also added a fourth single box option METHODS Largest contiguous areas of b-c

20 Combination Assessment Rudder proposal not equivalent habitat protection Rudder proposal Area of C-B 98 nm 2 (40.6%) Target 132 nm 2 (54.8%) METHODS Contiguous C-B

21 Combination Assessment Rudder proposal not equivalent habitat protection Rudder proposal Area of C-B 98 nm 2 (40.6%) Target 132 nm 2 (54.8%) Added on units, attempting to keep boundaries manageable and stay within the 50 meter contour 63 possible combinations, Rudder plus abcdef abcde abcdf. Removed complicated boundary options (such as abd), leaving 29 possible combinations METHODS Rudder proposal Contiguous C-B

22 Rudder AND % cobbleboulder Boundary assessment abcdef 67.9 good abcef 64.9 good 12 combinations meet or exceed the target acdef 63.7 good abc 62.1 iffy acef 60.7 good bcdef 59.2 good acf 58.6 iffy ac 57.9 good bcd 56.3 good bcef 56.2 good Target is 54.8% cobble-boulder cover adef 55.2 good cdef 55.0 good cde 54.2 good bc 53.3 good ad 52.3 iffy aef 52.2 good cd 52.1 iffy cef 52.0 good af 50.1 iffy cf 49.9 good a 49.4 iffy c 49.1 good def 46.5 good de 45.7 iffy b 44.8 iffy d 43.6 iffy ef 43.5 good RESULTS e 42.7 iffy f 41.4 good Rudder 40.6 good Contiguous C-B

23 Rudder Total in original boxes Rudder+cdef Rudder+adef Rudder+bcef Rudder+bcd Rudder+ac Rudder+acf Rudder+bcdef Rudder+acef Rudder+abc Rudder+acdef Rudder+abcef Rudder+abcdef These are the combinations that meet or exceed the amount of cobble-boulder in the original 4 AE areas. Total Size Sand-Mud-Silt Granule-Pebble Boulder-Cobble RESULTS Area NM 2

24 RESULTS Contiguous C-B

25 RESULTS Contiguous C-B

26 RESULTS Contiguous C-B

27 RESULTS Contiguous C-B

28 RESULTS Contiguous C-B

29 Hard to pick best option GOAL BEST OPTION Most similar C-B coverage as original 4 boxes Rudder + CDEF Stay shallower than 40 m contour Rudder + CDEF (can t get to target w/o D) User conflict avoidance Rudder + CDEF (can t get to target w/o C) Most representative (equal amounts sandgravelcobble/boulder) Rudder + AC Targeting heavily fished areas Rudder + ABC Maximum coverage of cobble-boulder in 1 box Rudder + ABCDEF Smallest total area that meets or exceeds b-c target Rudder + AC Contiguous C-B

30 Hard to pick best option GOAL BEST OPTION Most similar C-B coverage as original 4 boxes Rudder + CDEF Stay shallower than 40 m contour Rudder + CDEF (can t get to target w/o D) User conflict avoidance Rudder + CDEF (can t get to target w/o C) Most representative (equal amounts sandgravelcobble/boulder) Rudder + AC Targeting heavily fished areas Rudder + ABC Maximum coverage of cobble-boulder in 1 box Rudder + ABCDEF Smallest total area that meets or exceeds b-c target Rudder + AC Contiguous C-B

31 Hard to pick best option GOAL BEST OPTION Most similar C-B coverage as original 4 boxes Rudder + CDEF Stay shallower than 40 m contour Rudder + CDEF (can t get to target w/o D) User conflict avoidance Rudder + CDEF (can t get to target w/o C) Most representative (equal amounts sandgravelcobble/boulder) Rudder + AC Targeting heavily fished areas Rudder + ABC Maximum coverage of cobble-boulder in 1 box Rudder + ABCDEF Smallest total area that meets or exceeds b-c target Rudder + AC Contiguous C-B

32 Hard to pick best option GOAL BEST OPTION Most similar C-B coverage as original 4 boxes Rudder + CDEF Stay shallower than 40 m contour Rudder + CDEF (can t get to target w/o D) User conflict avoidance Rudder + CDEF (can t get to target w/o C) Most representative (equal amounts sandgravelcobble/boulder) Rudder + AC Targeting heavily fished areas Rudder + ABC Maximum coverage of cobble-boulder in 1 box Rudder + ABCDEF Smallest total area that meets or exceeds b-c target Rudder + AC Contiguous C-B

Boundary modification specific to achieving a goal could add value Move northern boundary a bit north to capture more hard bottom without affecting the eastern 40/50 m contour?

33 Boundary modification specific to achieving a goal could add value Move northern boundary a bit north to capture more hard bottom without affecting the eastern 40/50 m contour? Move western boundary a bit east to minimize coverage of non-target bottom (how does this affect representativeness)? Any movement east captures hard bottom that is heavily scalloped RESULTS

Great South Channel Habitat Management Area Analysis. Committee tasking

Great South Channel Habitat Management Area Analysis NEFMC Habitat Committee Meeting March 19, 2013 Salem, MA Committee tasking MOTION 5, (McKenzie, Alexander) from 12 4 12 meeting Move that the Committee