Defining critical habitat for large whales in Newfoundland and Labrador waters: design and assessment of a step-by-step protocol

Abgrall, Patrick (2009) Defining critical habitat for large whales in Newfoundland and Labrador waters: design and assessment of a step-by-step protocol. Doctoral (PhD) thesis, Memorial University of Newfoundland.

[English] PDF - Accepted Version Available under License - The author retains copyright ownership and moral rights in this thesis. Neither the thesis nor substantial extracts from it may be printed or otherwise reproduced without the author's permission. Download (15MB)

Abstract

The aim of this study was to develop a procedure to define critical habitat for species at risk under the Species at Risk Act and apply it to blue, fin, and sei whales in an effort to increase our understanding of their habitat use and preference around Newfoundland and Labrador. To achieve this goal, a step-by-step protocol was developed to help scientists and decision makers achieve habitat protection goals for species at risk: Step 1 - natural history description; Step 2 - population concentrations as habitat ranking markers (Candidate Critical Habitats); Step 3 - assessing limiting resources and limiting factors (Protected Critical Habitats); and Step 4 - active monitoring. -- Areas of high population concentrations, including seasonal peaks, for blue, fin, and sei whales were identified through historical shore-based whaling records and the Department of Fisheries and Oceans' cetacean sightings database. These areas were labelled as initial candidate critical habitats and include: the south coast of Newfoundland during spring and summer and the Strait of Belle Isle/Gulf of St. Lawrence during spring for blue whales; coastal Labrador and northeast Newfoundland during summer for fin whales; and the south coast of Newfoundland during summer and coastal Labrador during summer and autumn for sei whales. These regions were demonstrated to have served historically as feeding habitats for all of these species. -- An Ecological Niche Factor Analysis (ENFA), using ecogeographical variables (water depth, seabed slope, sea-surface temperature, and chlorophyll concentrations), provided more precise models of habitat suitability and candidate critical habitats. Results of the ENFA indicated that blue whale distribution around Newfoundland and Labrador was found to be mainly correlated with areas of deep water and steep seabed slope, and particularly off the south coast of Newfoundland, with the steepness of the seabed slope. Fin whale and sei whale distribution were correlated mainly with deeper than average waters and colder surface waters. Season-specific critical habitat models were also generated, but were generally low in their predictive accuracy. When the models were challenged with a limited set of aerial survey sighting records that were not used in the ENFA, 64% of blue whale sigh lings (n = 11) and 60% of fin whale sightings (n = 10) were located within core habitat as defined by ENFA. Finally, potential limiting factors were summarized and conditions were highlighted under which these candidate critical habitats should become protected critical habitats.

Actions (login required)

View Item