Aerial surveys of cetaceans in the Gulf of St. Lawrence in 1995 and 1996

1998 ◽  
Vol 76 (8) ◽  
pp. 1529-1550 ◽  
Author(s):  
MCS Kingsley ◽  
R R Reeves
Keyword(s):  
Humpback Whales ◽  
Delphinapterus Leucas ◽  
Line Transect ◽  
Balaenoptera Acutorostrata ◽  
North Shore ◽  
The North ◽  
Minke Whales ◽  
Fin Whales ◽  
Pilot Whales ◽  
Blue Whales

Aerial line-transect surveys of cetaceans were flown in the Gulf of St. Lawrence in late August and early September of 1995 and in late July and early August of 1996. Systematic north-south transects were spaced 15prime of longitude apart. In 1995, the study area comprised the entire Gulf, divided into three strata for analysis; 69% was flown. In 1996, a single stratum covered only the north shore shelf; 75% of the design was flown. The survey platform was a light high-winged aircraft with bubble windows flown at 213 m (700 ft). Ten species were seen. Minke whales (Balaenoptera acutorostrata), Atlantic white-sided dolphins (Lagenorhynchus acutus), and harbour porpoises (Phocoena phocoena) yielded enough sightings to support good estimates, while fin whales (Balaenoptera physalus), humpback whales (Megaptera novaeangliae), white-beaked dolphins (Lagenorhynchus albirostris), and long-finned pilot whales (Globicephala melas) yielded few sightings and unreliable estimates. Blue whales (Balaenoptera musculus) and belugas (Delphinapterus leucas) were seen too rarely to support any analysis. The tenth species was a small delphinid, not positively identified. Minke whales were ubiquitous, but more common in the northern strata. We estimated about 1000 in the whole Gulf in 1995 and about 600 in the northernmost stratum in 1996 (these numbers, and those following, are uncorrected for visibility bias). We estimated about 12 000 Atlantic white-sided dolphins in the Gulf in 1995, but in 1996 saw hardly any, perhaps because we flew the survey earlier. Harbour porpoises (12 000 in 1995 and 21 000 in 1996) were most numerous in the northern stratum, but were also widely distributed at lower densities in the central and southern Gulf. White-beaked dolphins (2500 in 1995 and 2500 in 1996) occurred only in the Strait of Belle Isle and the extreme northeastern Gulf. We estimated a few hundred fin whales in the northern and central strata and about 100 humpbacks, mostly in the northeast. Long-finned pilot whales were only seen in the southeastern Gulf, surveyed only in 1995 (about 1500).

scholarly journals Trends in the distribution and abundance of cetaceans from aerial surveys in Icelandic coastal waters, 1986-2001

2009 ◽  
Vol 7 ◽  
pp. 117 ◽  
Author(s):  
Daniel G Pike ◽  
Charles GM Paxton ◽  
Thorvaldur Gunnlaugsson ◽  
Gísli A Víkingsson
Keyword(s):  
Relative Abundance ◽  
Minke Whale ◽  
Humpback Whales ◽  
Line Transect ◽  
Survey Area ◽  
Balaenoptera Acutorostrata ◽  
The North ◽  
Aerial Surveys ◽  
Minke Whales ◽  
Abundance Estimates

Aerial surveys were carried out in coastal Icelandic waters 4 times between 1986 and 2001 as part of the North Atlantic Sightings Surveys. The surveys had nearly identical designs in 3 of the 4 years. The target species was the minke whale (Balaenoptera acutorostrata) but all species encountered were recorded. Sighting rate and density from line transect analysis were used as indices of relative abundance to monitor trends over the period, and abundance estimates corrected for perception biases were calculated for some species from the 2001 survey. More than 11 species were sighted, of which the most common were the minke whale, humpback whale (Megaptera novaeangliae), dolphins of genus Lagenorhychus, and the harbour porpoise (Phocoena phocoena). Minke whales anddolphins showed little change in distribution or abundance over the period. There were an estimated 31,653 (cv 0.30) dolphins in the survey area in 2001. Humpback whales increased rapidly at a rate of about 12%, with much of the increase occurring off eastern and northeastern Iceland. In 2001 there were an estimated 4,928 (cv 0.463) humpback whales in the survey area. The relative abundance of harbour porpoises decreased over the period, but estimates for this species were compromised by uncorrected perception biases and poor coverage. The ecological and historical significance of these findings with respect to previous whaling activities and present-day fisheries is discussed.

Occurrence and general behavior of balaenopterid cetaceans summering in the St. Lawrence Estuary, Canada

1987 ◽  
Vol 65 (6) ◽  
pp. 1363-1376 ◽  
Author(s):  
Peggy L. Edds ◽  
J. Andrew F. Macfarlane
Keyword(s):  
Abundant Species ◽  
Humpback Whales ◽  
Lawrence Estuary ◽  
The Past ◽  
North Shore ◽  
The North ◽  
Minke Whales ◽  
Field Season ◽  
St Lawrence Estuary ◽  
Blue Whales

Baleen whale movements were monitored from a hillside on the north shore of the St. Lawrence Estuary from 28 June to 27 September 1979. No diurnal or tidal relationships were apparent for the two most abundant species, the minke and finback. Single minke whales were seen almost daily. Adult pairs were only seen on four dates, and no adult-calf pairs were observed. Twenty-two small minkes were observed; three were possibly 1st-year calves. Finbacks occurred singly and in groups, particularly later in the field season. Resightings of distinctive finbacks indicate that adult pairings are temporary. One finback had been seen in the area in 1973–1975. Adult–calf pairs and seven single juveniles were also seen. Observations of finbacks pursued by whale watchers provide evidence that some regulation of the rapidly growing whale-watching industry may be warranted. Blue whales and humpback whales were seen far less frequently than minkes and finbacks. The relative abundances of minke, finback, and humpback were similar to 1973–1974 in the same area: however, blue whales were seen far more frequently in the past.

scholarly journals Distribution and Abundance of Cetaceans in Icelandic Waters over 30 Years of Aerial Surveys

2020 ◽  
Vol 11 ◽  
Author(s):  
Daniel Pike ◽  
Thorvaldur Gunnlaugsson ◽  
Johann Sigurjonsson ◽  
Gisli Vikingsson
Keyword(s):  
Relative Abundance ◽  
Humpback Whales ◽  
Line Transect ◽  
Balaenoptera Acutorostrata ◽  
Aerial Surveys ◽  
Minke Whales ◽  
Abundance Estimates ◽  
Ecosystem Changes ◽  
Common Minke Whale ◽  
Icelandic Waters

Beginning in 1986, 7 aerial surveys covering the coastal waters of Iceland have been conducted up to 2016. In addition, several partial surveys covering portions of the same area and at different times of the year have been flown in the same 30 year time span. We present previously unpublished abundance estimates, corrected to the extent feasible for known biases, for common minke whales (Balaenoptera acutorostrata), humpback whales (Megaptera novaeangliae), white-beaked dolphins (Lagenorhynchus albirostris) and harbour porpoises (Phocoena phocoena) from some or all of the 2007, 2009 and 2016 surveys. The relative abundance of most species was comparatively low in the spring and fall, and peaked June and July when all of the main surveys have been carried out. An analysis of changes in line transect density as an index of relative abundance from all surveys indicates that common minke whale abundance decreased by 75% after 2001 and has remained at a relatively low level since then. Relative abundance of humpback whales and white-beaked dolphins has increased over the period 1986-2016. We place these observed changes in context with oceanographic and ecosystem changes documented over the same period.

scholarly journals Temporal Variability of Cetaceans near Halifax, Nova Scotia

2006 ◽  
Vol 120 (1) ◽  
pp. 93 ◽  
Author(s):  
Peter Simard ◽  
Jennifer L. Lawlor ◽  
Shannon Gowans
Keyword(s):  
Nova Scotia ◽  
North Atlantic ◽  
Humpback Whales ◽  
Eubalaena Glacialis ◽  
Balaenoptera Acutorostrata ◽  
Minke Whales ◽  
North Atlantic Right Whales ◽  
Early Fall ◽  
Large Groups ◽  
Blue Whales

Annual and seasonal trends in sightings of coastal cetaceans near Halifax, Nova Scotia, were studied using observations from whale watching and dedicated research vessels from late spring to early fall of 1996 to 2005. Four species of cetaceans routinely used the area during the summer: White-beaked and Atlantic White-sided dolphins (Lagenorhynchus albirostris and L. acutus), Harbour Porpoises (Phocoena phocoena), and Minke Whales (Balaenoptera acutorostrata). The dolphin species were temporally separated, with White-beaked Dolphins being common earlier in the summer than White-sided Dolphins. White-sided Dolphins were unusually abundant in 1997, and were found in larger groups (mean = 46.5 ± 46.19 sd) than Whitebeaked Dolphins (mean = 9.1 ± 5.19 SD). The area also appears to be an important habitat for dolphin calves and juveniles of both species. Fin Whales (B. physalus) were commonly observed in relatively large groups in 1997, but were uncommon or absent in other years. Humpback Whales (Megaptera novaeangliae), Blue Whales (B. musculus) and North Atlantic Right Whales (Eubalaena glacialis) were uncommon in the area, although Humpback Whales were sighted frequently in 1997. Increased numbers of White-sided Dolphins, Fin and Humpback whales in 1997 may be explained by increased prey abundance and decreased sea-surface temperatures.

Accounting for responsive movement in line transect estimates of abundance

2001 ◽  
Vol 58 (4) ◽  
pp. 777-787 ◽  
Author(s):  
D L Palka ◽  
P S Hammond
Keyword(s):  
Animal Movement ◽  
Generalized Additive Models ◽  
Radial Distance ◽  
Additive Models ◽  
Line Transect ◽  
The North ◽  
Minke Whales ◽  
Orientation Density ◽  
Using Data ◽  
Animal Orientation

A method is developed to account for effects of animal movement in response to sighting platforms in line transect density estimates using data on animal orientation. Models of expected distributions of animal orientation show that presence of responsive movement is determined by the ratio of animal sightings with angles of orientation in the third quadrant relative to the first quadrant. The distance at which response began is estimated using logistic generalized additive models of the relationship between radial distance and orientation. Density corrected for responsive movement is estimated by applying the Buckland and Turnock two-team analysis method to data poststratified into regions "close" to and "far" from (beyond the distance that responsive movement began) the observation platform instead of the original stratification by observation team. For data collected in the North Atlantic, white-sided dolphins, harbor porpoises, and minke whales responded by avoiding the survey ship, and white-beaked dolphins were attracted to the ship. For these populations, our method to correct for responsive movement gave significantly higher estimates, from 1.4 to 2.7 times the uncorrected estimates.

Interspecific cetacean interactions during the breeding season of humpback whale (Megaptera novaeangliae) on the north coast of Bahia State, Brazil

2009 ◽  
Vol 89 (5) ◽  
pp. 961-966 ◽  
Author(s):  
Marcos R. Rossi-Santos ◽  
Elitieri Santos-Neto ◽  
Clarêncio G. Baracho
Keyword(s):  
Breeding Season ◽  
Megaptera Novaeangliae ◽  
Humpback Whales ◽  
North Coast ◽  
Balaenoptera Acutorostrata ◽  
Cetacean Species ◽  
The North ◽  
Eastern Brazil ◽  
North Eastern ◽  
Stenella Attenuata

The large majority of cetacean interspecific studies report only on dolphin interactions, while studies on interactions between odontocete and mysticete are less common. The present work aims to report on sightings of cetacean interactions, during the breeding season of humpback whales(Megaptera novaeangliae), along 370 km of the Bahia State, north-eastern Brazil, addressing aspects of cetacean distribution and behaviour. During 7 seasons (2000–2006), a total of 230 research cruises were performed, in which 38 events of interactions among humpback whales and other cetaceans(Tursiops truncatus, Steno bredanensis, Peponocephala electraandBalaenoptera acutorostrata)were observed, plus another 5 encounters without the whale's presence, includingT. truncatus, S. bredanensis, P. electra, Stenella clymeneandStenella attenuata. Our results confirm the occurrence of multiple cetacean species in the Bahia State, being the first study in the world to report on a large range of interactions involving another 4 cetacean species, grouped with up to 3 mixed species per sighting, with humpback whales in their annual breeding ground.

scholarly journals Changes in blood testosterone and progesterone concentrations of the North Atlantic minke whale (Balaenoptera acutorostrata) during the feeding season

2004 ◽  
Vol 61 (2) ◽  
pp. 230-237 ◽  
Author(s):  
Matthías Kjeld ◽  
Árni Alfredsson ◽  
Örn Ólafsson ◽  
Morten Tryland ◽  
Ivar Christensen ◽  
...  
Keyword(s):  
Frequency Distribution ◽  
North Atlantic ◽  
Minke Whale ◽  
Balaenoptera Acutorostrata ◽  
Hunting Season ◽  
P Values ◽  
The North ◽  
Minke Whales ◽  
The North Atlantic ◽  
Cyclic Changes

An opportunity to study seasonal changes of sex hormones in the North Atlantic minke whale (common minke whale, Balaenoptera acutorostrata) arose when we obtained access to fresh postmortem blood samples from 104 females and 83 males. The whales were caught in the North Atlantic during May–September 1992–1995. Serum progesterone (P) and testosterone (T) concentrations were measured and compared with anatomical data. The frequency distribution of female serum P values showed two clusters, one consisting mainly of immature animals and the second of pregnant ones, with mean serum values of about 0.49 ± 0.04 (SE) and 44.2 ± 2.84 nmol·L–1, respectively. The frequency distribution of male serum T did not show any group-specific distribution during the hunting season. The mean serum T value for the males was 0.63 ± 0.13 nmol·L–1. Contrary to earlier reports on the Antarctic minke whale (Balaenoptera bonaerensis), serum T values rose during the hunting season in mature males (p < 0.0001). Serum P values in immature females increased during the season (p = 0.015). This increase agrees with the predominantly annual reproduction cycle of minke whales. Blood sex hormone measurements seem to be useful for detecting cyclic changes and pregnancy of minke whales.

Marking of Small Cetaceans Using "Discovery" Type Whale Marks

1975 ◽  
Vol 32 (7) ◽  
pp. 1237-1240 ◽  
Author(s):  
S. G. Brown
Keyword(s):  
Minke Whale ◽  
Orcinus Orca ◽  
Killer Whales ◽  
Balaenoptera Acutorostrata ◽  
Lagenorhynchus Obscurus ◽  
Minke Whales ◽  
Beaked Whales ◽  
Pilot Whales ◽  
Dusky Dolphin

All smaller cetaceans known to have been successfully marked with "Discovery" type marks are summarized. These include 67 minke whales (Balaenoptera acutorostrata), 33 killer whales (Orcinus orca), 30 pilot whales (Globicephala sp.), 7 bottlenose whales (Hyperoodon sp.), 5 other "beaked whales," and 1 dusky dolphin (Lagenorhynchus obscurus). Recoveries include 3 minke, 1 bottlenose, and 1 killer. Minke whale marks were recovered up to 4 yr 2 mo after marking.

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