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Apr05NEIT Nichols presentation

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Published on November 6, 2007

Author: Elliott

Source: authorstream.com

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Slide1:  A simple two-dimensional model of ship encounter risk for right whales in Cape Cod Bay: Final results and management implications Owen C. Nichols1, Hauke L. Kite-Powell2, Robert D. Kenney3, Moira W. Brown4      1) Center for Coastal Studies, PO Box 1036, Provincetown, MA 02657, USA 2) Marine Policy Center, Woods Hole Oceanographic Institution, MS 41, Woods Hole, MA 02543, USA 3) Graduate School of Oceanography, University of Rhode Island, Bay Campus Box 41, Narragansett, RI 02882, USA 4) New England Aquarium, Central Wharf, Boston, MA 02110, USA Slide2:  Objectives: Provide a baseline estimate of risk to right whales from collisions with shipping traffic in Cape Cod Bay Evaluate potential management measures designed to reduce collision risk Slide3:  Aerial Surveys 1998-2002 Slide4:  Sightings Per Unit Effort (SPUE) The sampling season was defined as December through mid-May and divided into twelve two-week periods (1 December – 17 May) Study area partitioned into 117 3-minute quadrats (23 km2) 14 quadrats completely over land; thus 103 quadrats sampled Standardized aerial survey effort: visibility  2 nm, sea state ≤ 3, altitude < 325 m (1066 ft), observers on watch Only sightings and effort meeting the above criteria used in analysis Slide5:  Sightings Per Unit Effort (SPUE) Total effort and total sightings within each quadrat summed by year and separated into two-week periods SPUE = right whales sighted/1000 km survey effort / Kriging interpolation algorithm* used to estimate SPUE at twice the geographic resolution (1.5 minute quadrats) * GLOBEC Kriging Software Package, Dezhang Chu, WHOI Number of whales sighted divided by effort to generate SPUE index Slide18:  Density Estimates SPUE converted to density estimate (whales/km2) for each 1.5 min quadrat over 2-week periods - assuming 3 km effective survey swath Slide19:  Data provided by USACE Cape Cod Canal Field Office 6 routes based on origin/destination in USACE dataset ~ 7 vessel movements/day: 4 - Boston, 2 - Gulf of Maine 75% of the traffic is tug-barge combinations Vessel Transits Slide20:  Routes (based on origin/destination in USACE dataset) Slide22:  Calculation of Expected Ship/Whale Encounters For each route and 2-week period, the expected number of ship/ whale encounters was calculated based on the passage of a known number of vessels through quadrats of estimated right whale density Effective beam (width of path “swept” by vessels) estimated based on vessel type: tug = 10m; tug-barge, dry cargo, passenger = 15 m; tanker = 20m Routes divided into 1 km segments – right whale density is assumed based on the 1.5 min quadrat over which most of the segment lies Assumptions: whales always at surface and neither whales nor vessels attempt to avoid collision # of ship/whale encounters = area of path “swept” by vessel (beam x 1 km) x density (whales/km2) Slide24:  Expected Ship/Whale Encounters Results of model = 1.5 ship/whale encounters/year Boston traffic contributes ~ 46% of expected encounters, while Gulf of Maine traffic contributes ~ 35% - the latter poses high risk despite relatively low volume - transects areas of high whale density Slide25:  Two proposals incorporated into model Proposal A: Simple demonstration exercise Effects of Rerouting Proposal B: Draft routing option presented at ANPR meetings Both proposals involved shifting Boston, Gulf of Maine, and Provincetown traffic to the west Slide28:  Expected ship-whale encounters reduced by about 60% on the Gulf of Maine route and by about 40% on the Provincetown and Boston routes Effects of Rerouting Across all routes, reduction of 37% (Proposal A) to 45% (Proposal B) in the overall ship-whale encounter risk for Canal traffic in Cape Cod Bay (from ~ 1.5 encounters/year to ~ 0.9) Slide29:  Model results allow identification and comparison of areas of risk to right whales – baseline estimate that can be used to inform management decisions Expected encounters calculated based on several assumptions – Model can be refined with additional data as it becomes available: detection probability for density estimates, surface/dive and avoidance behavior, addition of subsequent years of right whale and traffic data Summary Routing existing vessel traffic away from known concentrations of right whales will cause a quantifiable reduction of the potential number of ship/whale encounters Slide30:  Acknowledgements Funding provided by the NOAA Fisheries North Atlantic Right Whale Competitive Grant Program Aerial surveys supported by the Massachusetts Division of Marine Fisheries as part of the Commonwealth of Massachusetts Right Whale Conservation Plan – funding sources include National Fish and Wildlife Foundation, NOAA Fisheries, Massachusetts Environmental Trust, and the Northeast Consortium – Special thanks to Dan McKiernan Vessel traffic data provided by the US Army Corps of Engineers Cape Cod Canal Field Office – Scott Barr, Bill Norman and Fran Donovan - Guidance and advice on routes: Pat Gerrior, Bruce Russell

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A simple two-dimensional model of ship encounter risk for right whales in Cape Cod Bay: Final results and management implications Owen C. Nichols1, Hauke L ...
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