Research Document 2018/003

Vulnerability assessment of 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 fuelled by the increase in oil tanker size and the density of marine traffic. The Government of Canada therefore reviewed and updated Canada's Marine Oil Spill Preparedness and Response 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. The DFO in the National Capital Region was mandated to develop a methodology to assess biological vulnerabilities in the aquatic environment (National Framework). This framework was enforced regionally by the Quebec region in the pilot area of the St. Lawrence Area Response Plan (ARP).

This document aims to assess the vulnerability of biological components: marine and estuary algae and plants, marine and estuary invertebrates, marine, estuary and diadromous fish, and marine mammals in the St. Lawrence against oil spills due to ships, as well as assess the adequacy and applicability of the changes made to the National Framework by the Quebec region for the pilot area of the St. Lawrence ARP. The vulnerability assessment was performed using four criteria relating to the exposure potential and the resilience of juvenile and adult stages of various taxa or groups of taxa that were assessed.

The vulnerability assessment made it possible to identify 136 taxa groups of 323 that were assessed with increased vulnerability in the event of spills. This represents 42% of all taxa assessed, including 28% of algae and plants, 56% of invertebrates, 23% of fish and 23% of marine mammals. The total uncertainty related to the assessment is 25%: 20% for algae and plants, 34% for invertebrates, 9% for fish and nil for marine mammals. These uncertainties affected ranking accuracy. They are attributable mainly to the population status criterion. The regional adaptation of the National Framework made it possible to address the mandate and ensure the methodology was applicable to the biological realities of the St. Lawrence ARP. This could be used in other areas or regions.

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