Research Document 2018/003

Assessment of the Vulnerability of the Biological Components of the St. Lawrence to Ship-source Oil Spills

By Desjardins, C., Hamel, D., Landry, L., Scallon-Chouinard, P.-M. and Chalut, K.

Abstract

In Canada, assessing and mitigating the impacts of marine-transport-related oil spills is a major concern, driven by the increase in oil tanker size and in the density of marine traffic. The Government of Canada therefore reviewed and updated Canada’s Ship-source Oil Spill Response and Preparedness Regime to address this concern. This Canadian government need led to the implementation of the Area Response Planning Initiative (ARPI) by Transport Canada (TC) and the Canadian Coast Guard (CCG) in four pilot areas of the country. DFO National Capital Region was mandated to develop a methodology to assess the vulnerabilities of the biological components of the aquatic environment (the National Framework). This framework (Thornborough et al. 2017) was implemented regionally by DFO Quebec Region in the St. Lawrence Area Response Plan (ARP) pilot area.

This document aims to assess the vulnerability of biological components in the St. Lawrence— including marine and estuarine algae and plants; marine and estuarine invertebrates; marine, estuarine and diadromous fish; and marine mammals—to ship-source oil spills, as well as to assess the appropriateness and applicability of the changes made by the Quebec Region to the National Framework for the St. Lawrence ARP pilot area. The vulnerability assessment was performed using four criteria related to exposure potential and four criteria related to resilience in the juvenile and adult stages of the various taxa or taxa groups under evaluation.

The vulnerability assessment made it possible to identify 136 taxa groups (among the 323 taxa groups assessed) with a high level of vulnerability to oil spills. These highly vulnerable groups represent 42% of all taxa assessed, and include 28% of algae and plants, 56% of invertebrates, 23% of fish, and 23% of marine mammals. An overall uncertainty level of 25% was associated with the assessment: 20% for algae and plants, 34% for invertebrates, 9% for fish, and none for marine mammals. These uncertainties, which affected the accuracy of scoring, are mainly attributable to the population status criterion. The regional adaptation of the National Framework made it possible to fulfill the mandate and ensured that the methodology was applicable to the biological realities of the St. Lawrence ARP. This methodology could be used in other areas or regions.

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