Great South Channel Habitat Management Area Analysis. Committee tasking

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Kenneth Miller
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1 Great South Channel Habitat Management Area Analysis NEFMC Habitat Committee Meeting March 19, 2013 Salem, MA 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) 1

2 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) 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. 2

3 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. Selected Great South Channel (GSC) study area Study area selection necessary to compare original and new boxes* Encompasses original 4 adverse effects/habitat management areas (in blue) Encompasses Nantucket Shoals Federal waters only * for example, X% of the Great South Channel is boulder cobble 3

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

Some of this coastal current flows south around Nantucket Shoals, while some turns east and joins the northeastward flow along the

Right whale critical habitat area and shipping channel are prominent in the region.

GC 2009 0 79 Scallop LA 2009 0 391 Trawl 2009 0 8211 These are realized Z outputs from the SASI model.

4 Miller et al 1998 Oceanography 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 Belkin et al 2009 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 Lots of scalloping between meters, GC boats in shoaler water north of Nantucket. 4

Substrate polarmet.osu.edu GSC was near the southernmost extent of the glaciers in the last ice age.

the glacier melted. Every conceivable grain size is represented.

On top of the glacial deposits are reworked glacial deposits, including sand dunes. earthscience.

org Pratt & Schlee 1969 Bothner & Spiker 1980 Valentine 2002 Substrate This is a map focusing on the

5 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. earthscience.bcsdk12.org Pratt & Schlee 1969 Bothner & Spiker 1980 Valentine 2002 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? 5

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

6 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 Clusters of Hard Bottom This map highlights the largest areas of contiguous bouldercobble dominated seafloor Largest contiguous areas of cobble boulder dominated seafloor 6

7 Clusters of Hard Bottom LISA=local indicators of spatial association Shows where vulnerable seafloor is clustered P=0.05 is less clustered than p=0.01 LISA cluster (p 0.05) LISA cluster (p 0.01) 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 7

Less fishing of that gear type More fishing of that gear type These are the images side by side: LA GC Otter trawl Largest

8 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: LA GC Otter trawl Largest contiguous areas of b c The discussion with the scallopers led to the motion to consider a single box option with equivalent habitat value as the four boxes. 8

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

Nautical Miles (nm 2 ) 0 200 400 600 800 1,000 GSC Region 2,808 nm 2 590 nm 2 GSC 1 GSC 2 GSC 3 GSC 4 Sum GSC 1 4 136 nm 2 = 4.8% 144 nm 2 =24.4% 132 nm 2 = 54.

9 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 241 nm 2 Area in Sq. Nautical Miles (nm 2 ) ,000 GSC Region 2,808 nm nm 2 GSC 1 GSC 2 GSC 3 GSC 4 Sum GSC nm 2 = 4.8% 144 nm 2 =24.4% 132 nm 2 = 54.8% METHODS Sand Mud Silt Granule Pebble Boulder Cobble 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 9

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

the s polygon and experimented with building out from it to achieve equivalent habitat protection; also added a fourth single box option METHODS Largest contiguous areas of b c Combination Assessment

10 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 s, VIMS After the January meeting, I took the s polygon and experimented with building out from it to achieve equivalent habitat protection; also added a fourth single box option METHODS Largest contiguous areas of b c Combination Assessment proposal not equivalent habitat protection proposal Target 132 nm 2 (54.8%) Area of C B 98 nm 2 (40.6%) proposal Added on units, attempting to keep boundaries manageable and stay within the 50 meter contour 63 possible combinations, plus abcdef abcde abcdf. Removed complicated boundary options (such as abd), leaving 29 possible combinations METHODS 10

11 % cobbleboulder Boundary AND 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 proposal 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 e 42.7 iffy f 41.4 good Total in original boxes +cdef +adef +bcef +bcd +ac +acf +bcdef +acef +abc +acdef +abcef +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 Area NM 2 11

12 polygon polygon 12

13 polygon polygon 13

14 polygon Hard to pick best option : GOAL Maximum coverage of cobble boulder in 1 box Smallest total area that meets or exceeds b c target Stay shallower than 40 m contour Simplest boundary Least sand coverage Most representative (equal amounts sandgravelcobble/boulder) User conflict avoidance Targeting heavily fished areas BEST* OPTION + ABCDEF +AC +CDEF (can t get to target w/o D) + CDEF +AC + AC +CDEF (can t get to target w/o C) + ABC * Boundary modification specific to achieving the goal would add value polygon 14

Others Analyzed New Box A polygon 98 New Box B Total in original boxes 132 New Box D New Box C 106 129 Total Area Sand Mud Silt Granule Boulder Cobble New Box C New Box B 115 New Box A 106 0 100 200

15 Others Analyzed New Box A polygon 98 New Box B Total in original boxes 132 New Box D New Box C Total Area Sand Mud Silt Granule Boulder Cobble New Box C New Box B 115 New Box A Area NM 2 New Box D Conclusion There are roughly a dozen good single box options. Without more guidance on how to select the boundaries to meet certain goals, the PDT cannot determine which is the best option. 15

Great South Channel Habitat Management Area Analysis

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