Research Document - 2009/008

An Ecological and Oceanographical Assessment of the Alternate Ballast Water Exchange Zone in the Hudson Strait Region

By D.B. Stewart and K.L. Howland

Abstract

This work considers the ecological risks of non-indigenous species introductions associated with ballast water exchange in the Hudson Strait region of Arctic Canada by vessels enroute to Hudson Bay and the Canadian eastern Arctic. Under the Canada Shipping Act (P.C. 2006-495 June 8, 2006) Ballast Water Control and Management Regulations, ballast water can be exchanged within Hudson Strait east of 70°W longitude where the water is at least 300 m deep. This Alternate Ballast Water Exchange Zone (ABWEZ) is used by ships that have not conducted a mid-ocean ballast water exchange outside Canada’s Exclusive Economic Zone (EEZ).

Very little is known of the oceanography and ecology of Hudson Strait and the Hudson Bay complex in general. Even less is known of potentially invasive biota being carried there in ballast water.  Based on information that is available, there are a few physical parameters that can be used to consider where best to locate an alternative ballast water exchange zone for the region.  These include depth, temperature, salinity, distance from shore, currents, tidal range, and ice cover. Within Hudson Strait, each of these parameters offers a range of possibilities that can make it easier or harder for invasive species from warmer coastal waters to establish.

The deep, cold, relatively saline and seasonally ice-covered waters of the existing ABWEZ are removed from shore and subject to strong eastward currents. They remain the preferred exchange zone within Hudson Strait. These same characteristics also mean that the biota taken up during the exchange may be less likely to establish in the shallower, warmer, less saline coastal waters near Churchill.

All vessels entering the Canadian Eastern Arctic via Hudson Strait should follow the same procedures as transoceanic vessels, namely ballast water exchange for vessels with ballast on board and saltwater flushing of ballast tanks for ships with no ballast on board. This precautionary approach should be followed until ballast water treatment is implemented for these vessels or research demonstrates that the risk is acceptable. Otherwise the spread of non-indigenous species from domestic coastal waters is uncontrolled.

Further research is recommended to assess the risk of species introductions associated with ballast water exchange in Hudson Strait and with its release by foreign and domestic vessels within the Hudson Bay complex. The relative merits of conducting ballast water exchange east of Hudson Strait in the Labrador Sea, rather than within Hudson Strait, should also be considered.

Complete document (PDF, 3325 KB)

Accessibility Notice

This document is available in PDF format. If the document is not accessible to you, please contact the Secretariat to obtain another appropriate format, such as regular print, large print, Braille or audio version.