South Pacific humpback whales were devastated by commercial whaling in their
Antarctic feeding areas during the 20th century. Understanding migratory
connections and current abundance of these isolated breeding stocks is crucial
for the allocation of historical Antarctic catches in population dynamic models
used to assess current recovery. However, only a small number of migratory
connections have been documented between Oceania breeding stocks within the
South Pacific and feeding areas in the Antarctic. In addition, little is known about
abundance of these stocks which encompass a vast oceanic region. For this
thesis I first used mixed-stock analysis (MSA) to allocate migratory connections
from four Antarctic feeding areas (n=142) to seven South Pacific breeding stocks
(n=1,373), including four in Oceania, based on genetic marker frequencies. The
use of this method was justified by the breeding stocks showing genetic
differentiation at the haplotype level with an F[subscript ST] value of 0.027 (p-value <0.001).
The results showed a relatively strong connection of Western Australia to
Antarctic Area IV, Tonga to the border of Antarctic Area VI/I, Colombia to the
Antarctic Peninsula, and a split allocation of Eastern Australia and New
Caledonia to Antarctic Area V. This study provides the first population-level
information supporting previous individual-based studies that humpback whale
migration may not necessarily be direct north south. Next, utilizing capture-recapture
methodology of unique humpback whale fluke photographs, I
estimated abundance of one of the least studied Oceania breeding stocks,
French Polynesia, a stock which also showed no significant migratory allocation
using MSA. Taking into consideration the possible advantages of using Quality
Control (QC) photographs to minimize bias in matching, estimates were
generated using the complete photo catalogue and also using only photographs
adhering to QC criteria. I found that the choice of using QC has an effect on the
abundance generated and discuss the implications of this finding. Despite the
photo catalogue used, the French Polynesia stock is estimated to number less
than 1,900 individuals. Lastly, to provide additional information on the French
Polynesia stock I used photo-identification to compare French Polynesia whales
to whales in the Antarctic Peninsula and Strait of Magellan (Antarctic Area I), a
possible migratory connection suggested by previous microsatellite genotyping.
No conclusive matches were found. Although this does not discount the
possibility of a few migrants traveling between these regions it does indicate the
Antarctic Peninsula and the Strait of Magellan are not primary feeding areas of
French Polynesia. This new information regarding abundance and migration of
French Polynesia whales is important for the Comprehensive Assessment of
Southern Hemisphere humpback whales. This document is currently being
completed as the International Whaling Commission considers the next critical
steps in recovery for Oceania humpback whales stocks. / Graduation date: 2010
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/11995 |
| Date | 09 July 2009 |
| Creators | Gibb, Giselle Renee |
| Contributors | Baker, C. Scott |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
Page generated in 0.0101 seconds