Humpback, finback, minke and pilot whale distributions in Newfoundland and Labrador, 1976-1983

Lynch, Katherine Dayrell (1987) Humpback, finback, minke and pilot whale distributions in Newfoundland and Labrador, 1976-1983. Masters thesis, Memorial University of Newfoundland.

[English] PDF (Migrated (PDF/A Conversion) from original format: (application/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 (41MB) [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. (Original Version)

Abstract

An increase in the incidence of whale entrapments in fixed fishing gear in the late 1970s in Newfoundland and Labrador led to the establishment of a network of observers in April 1979, to monitor annual changes in inshore whale abundance. This thesis presents humpback, finback, minke and pilot whale sighting records, and evaluates the observer network both as a means of determining the spatial and temporal distribution of whales, and as a means of monitoring annual fluctuations in their relative abundance. -- An analysis of the sighting records (from land-based observers: 1979-1982 and from shipboard observers: 1976-1983) indicated similarities in the summer distributions (June-September) of the three species of baleen whales. Humpback, finback and minke whales shared an affinity for the east coasts for Newfoundland and Labrador. Minkes, however, were rarely seen offshore and appeared to be more dispersed than humpback and finback whales. Pilot whales were found to be distributed further south than the baleen whales. They frequented bays on the east, south and west coasts of Newfoundland. -- The temporal distributions resulting from this study indicated that all four species were most abundant during the months of historically high prey availability (capelin and squid). However, the monthly distributions of humpback, finback and pilot whales suggested that portions of each summer population arrived off the north coast of Newfoundland in May and June, apparently preceding the main inshore migration of capelin and squid to this area. -- The observer network appeared to provide an effective means of determining whale distribution. The reliability of whale identifications was checked through tests and field notes. The spatial and temporal distribution of observer effort was not correlated with the spatial and temporal distribution of the whales. Furthermore, the distributions resulting from this study overlapped with historical records of sightings and whaling catches for all four species. -- The shipboard observer network appeared to provide a more accurate means of monitoring annual changes in whale abundance than the land-based observer network. The land-based network failed to detect the post-1980 decrease in humpback whales in the inshore waters of east and southeast Newfoundland (as indicated by a decline in entrapment in fixed fishing gear). This was attributed mostly to the land-based network’s tendency to under-report observer effort during the periods of infrequent sightings.

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