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Research Document - 2012/149

An Ecological and Oceanographic Assessment of the Beaufort Sea Region: Evaluation of the Risks Associated with Ballast Water Exchange

By D. Fissel, W. Cross, and K. Howland

Abstract

This work considers the ecological risks of non-indigenous species introductions associated with ballast water exchange in the Beaufort Sea region of the Canadian Arctic. Normally foreign vessels are required to conduct mid-ocean ballast exchange outside the Canadian Exclusive Economic Zone, however in the event that this is not possible due to safety concerns, ships may conduct emergency ballast exchange in one of two designated alternate ballast water exchange zones (ABWEZs) within Canadian Arctic waters. To date, ABWEZs have been identified in the Hudson Strait and Lancaster Sound regions of the eastern Arctic for vessels traveling westbound to the Port of Churchill or the Northwest Passage, respectively. A need for a third zone in the western Arctic has been identified, and is considered a priority given the renewed interest in hydrocarbon development in this region.

Information on the ecology, oceanography, and shipping patterns in the Beaufort Sea region were reviewed to assess the potential risks of non-indigenous species introductions associated with ballast water exchange.

In the Canadian Beaufort Sea there are extensive areas of ecological significance associated with upwelling in the Mackenzie Trough and the outer shelf and slope regions of the Mackenzie, as well as over the middle and inner portions of the Mackenzie Shelf due to the influence of the Mackenzie River plume and frontal features. Based on these features, ballast water exchange should be avoided from the longitude of Herschel Island (139°W) eastward to the entrance to Amundsen Gulf (125°W) and from the coastline to approximately the 1000-m water depth contour.

Given the spatial constraints related to water depths and ecologically important areas, the potential locations for an ABWEZ are very limited, given the need to accommodate a linear ship track of 200–400 km long. Within these constraints, the waters to the west of Herschel Island at depths of 20–100 m along the route of most transiting vessels are incompatible with a potential ABWEZ because the distance from the Canada/US border is <100 km. Farther offshore at water depths of 100–1000 m, starting from the Canada/US border there is an area that extends in a WSW to ENE orientation, however, travel eastward along this track is limited in early August by the presence of significant ice concentrations. Although a sufficient linear transit track (> 200 km) becomes feasible in this location by mid-September, this is well beyond the entry dates of most commercial shipping in August.

Under present ice conditions combined with the water depths and ecologically sensitive area constraints, there are presently no feasible ABWEZ sites in the Canadian Beaufort Sea.

In the event that future sea ice conditions are reduced and ice retreats farther offshore in early to mid-summer, an ABWEZ site from the Canada/US border east-northeastward in water depths of 1000 m or more north of the Mackenzie Trough would become possible. This area would be reasonably feasible for ships that may be travelling to far offshore oil and gas license areas for which exploration is presently getting underway, and for transit to McClure Strait north of Banks Island, which represents the deepwater northern route of the Northwest Passage through the Canadian Arctic Islands.

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