Changes in cetacean occurrence in Faxaflói Bay, Iceland, as observed from whale watching vessels

We collected data on the distribution of Balaenoptera physalus (Finback Whale), Balaenoptera acutorostrata (Minke Whale), and Megaptera novaeangliae (Humpback Whale), in the Quoddy region of the Bay of Fundy, Canada, from a whale-watching vessel during commercial tours from 2006 to 2012. Sightings were non-random between species and showed clumped distributions over the study area: Finback Whales (χ2 = 2454.03, df = 7, P < 0.005), Minke Whales (χ2 = 3488.24, df = 7, P < 0.005), and Humpback Whales (χ2 = 301.784, df = 7, P < 0.005). Minke Whales were most frequently sighted in Head Harbour Passage, high concentrations of Finback Whales were most frequently sighted off Blacks Harbour, and Humpback Whale sightings were highest around The Wolves. It appears that the whales aggregate in response to physical and biological features of the environment, such as depth, bottom topography, and fine-scale oceanographic features that enable foraging. Oceanographic features such as tidal state and temperature also influence the distribution of whales by aggregating their common prey species in high concentrations.

Seasonal acoustic occurrences and diel singing patterns of humpback whale (Megaptera novaeangliae) songs and Antarctic minke (Balaenoptera bonaerensis) whale are described using acoustic recordings from the west coast of South Africa and Maud Rise, Antarctica. Acoustic data were recorded from early 2014 to early 2017. Acoustic occurrences (i.e., presence) of humpback and minke whale sounds were identified through visual scrutiny of spectrograms of recorded data. Environmental conditions associated with humpback whale song occurrences were ranked according to their model-predicted relative importance. In South Africa, humpback whale songs were detected from June to December but peaked in September. In Antarctica, humpback whale songs were detected from March to May (singing peaked in April). Minke whale sounds were only recorded in 2014, between June and September in Antarctica and between September and November in South Africa. Humpback whales were more vocally active at night in all recording sites whereas minke whales were more vocally active during the day. This is the first study to describe the seasonal acoustic occurrences of humpback and minke whales off the west coast of South Africa. Such knowledge could be essential for the conservation and management of these species in both South Africa and Antarctica.

The archipelago of the Azores is like an oasis in the middle of the Atlantic Ocean. Surrounded by deep waters, those islands are a “must stop” place for every traveler, including, of course, cetaceans. Around the archipelago more than 24 different species of whales and dolphins can be seen. Some of them are resident such as the common dolphin or the emblematic sperm whale. But others are seasonal or sporadic, such as the spotted dolphin or the big baleen whales. The aim of this study is to assess the temporal distribution of the baleen whales sighted off Azores. We analyzed data gathered off the south coast of São Miguel (Azores) from 2006 to 2013 from whale watching vessels. The whale watching company is located in Ponta Delgada and it works all throughout the year, always when the weather, the sea state and the number of tourists allow doing it. In Azores, whale watching companies use to locate cetaceans from land, with specialized lookouts spotting the animals from strategic points on the shore (as whalers did). These lookouts use powerful binoculars to locate the animals, and then give instructions to the boats to get to them. Once there, the boat registers date, hour, sea state, visibility, position (GPS), species, number of individuals, number of adults, juveniles and calves, behavior, association with other species and if there are other boats in the area. Photos are taken whenever it is possible and they are analyzed when the quality is good enough to distinguish natural marks and shapes. Most of the photos used in this study were taken in the last 5 years. Photo-Id catalogues were created for blue whales, fin whales and humpback whales. Data collected are more complete and frequent since 2009. In this case we have analyzed a total of 7691 sightings, belonging to 20 different species of cetaceans, 14 Odontoceti and 6 Mysticeti. In the latter group we recorded 491 sightings. The three most sighted Mysticeti species were the three great baleen whales: fin whale (<i>Balaenoptera physalus</i>) with 221 sightings, sei whale (<i>Balaenoptera borealis</i>) with 143 and blue whale (<i>Balaenoptera musculus</i>) with 83. Those three species were sighted regularly each season every year of the study. Following them, with a much smaller number of sightings, were minke whales (<i>Balaenoptera acutorostrata</i>) with 16, humpback whales (<i>Megaptera novaeangliae</i>) with 15 and Bryde’s whales (<i>Balaenoptera edeni</i>) with 13. Minke, humpback and Bryde’s whales were seen more rarely, being occasionally observed around the islands. The preferred time of the year for all species except Bryde’s, were spring months between March and June (81.7% of the sightings). Blue whales were more frequent in 2010 and 2012, having the highest sighting rates in May (32 sightings), April (24 sightings) and March (20 sightings), making up 91.6% of total blue whale records. Having into account March 2014 photos, we identified 75 different blue whales, and from those, only two were re-sighted in different years. One was firstly sighted on April 2010 with a calf and re-sighted alone on March 2014; and the other was firstly sighted on March 2012 and re-sighted on April 2014. 2013 was a good unusual year for fin whales, with a total number of 90 sightings seen mostly in may. Along the study period, we identified 45 fin whales, and at the moment, we didn’t get any match in different years or locations. Humpback whales were not sighted during 2006, 2007, 2008 and 2013, but we must bear in mind that our data from those years are incomplete (except for 2013). Nevertheless, they seem to have a slight preference for April-May as well. We photo-identified 12 individuals. One whale was re-sighted after only seven days, but there were no other re-sightings between seasons or years yet. For sei whales the best year was 2010, with 47 records. Most of records for both species were made in April and May, 66% of the fin whales and 54% of sei whales. Minke whales were sighted all years but 2007 and 2008. They don’t present any seasonal pattern, as they were seen in March, April, July, August and November. Bryde’s whales were sighted only in 2009 and 2013, and in both years were seen in summer (end of July-August). According to these findings we can conclude that fin whales, sei whales and blue whales are seasonal visitors in the Azores, as they are observed every year mainly in spring months between April and May. Those results agree with the hypothesis that great North Atlantic baleen whales (blue, fin and sei whales) are migratory [Olsen et al., 2009; Silva et al., 2013; Visser et al., 2011]. They pass off Azores mainly during spring months while they are travelling from their breeding grounds in low latitudes to their feeding grounds in the North Atlantic. However, if they are returning southwards to spend the winter, they have not been observed, so, if they do, they probably follow a different route. As a result, we believe that at least some blue whales usually pass along the Azores probably while they are moving to the North Atlantic feeding grounds. We have recorded two re-sightings of this species in different years, in the same area (south off São Miguel) and same time of the year (1 month lag). In another hand, we observed that minke whales, humpback whales and Bryde’s whales are only occasionally sighted around the islands. Minke and humpback don’t seem to have any preference of season, while Bryde’s were seen only in summer according to previous findings that suggest a temporal range expansion of the Eastern Atlantic population [Steiner et al., 2008]. To comprehend the occurrence of these marine mammals off Azores it would be interesting to better understand their migration and evaluate its relationship with oceanographic characteristics such as temperature, chlorophyll, currents and even geomagnetism. Next steps will be aimed at searching for these relationships and comparing our catalogues with others in the Atlantic in order to find new insights into the migration of baleen whales in the North Atlantic.

The fin whale (Balaenoptera physalus), humpback whale (Megaptera novaeangliae), and minke whale (Balaenoptera acutorostrata) are known to occur in the New York Bight (NYB). The primary North Atlantic feeding grounds for these large whale species are commonly recognized to be further north in waters of the Gulf of Maine, eastern Canada, West Greenland, and the eastern North Atlantic (e.g., Iceland, Norway, Ireland, Scotland). Although much is known about their feeding activities in the North Atlantic, relatively little is known about their occurrence and foraging behaviors in mid-Atlantic regions such as the NYB. Understanding how large whales utilize NYB waters is important to evaluate potential impacts from direct (e.g., offshore development, vessel strikes, entanglements) and indirect (e.g., rising ocean temperatures) anthropogenic sources. The New York State Department of Environmental Conservation funded a 3-year baseline monitoring program (2017-2020) which conducted monthly line-transect aerial surveys focused on large whales. Over 3 years, 36 surveys comprised of 263 flights and totaling 688.3 hours of observation time along 140,370 km of over-water flight path were completed. Aerial survey observers documented foraging events for the fin, humpback, and minke whales, including mixed-species aggregations, and analyzed other parameters such as distance from shore, distribution zones, and presence of fish schools. Foraging behavior was observed for 27% of the recorded fin whale sightings, 40% of the recorded humpback whale sightings, and 18% of the recorded minke whale sightings. Sighting rates of foraging whales were highest for humpback whales (4.4 whales/1,000 km of effort), followed by fin whales (0.6 whales/1,000 km effort) and minke whales (0.1 whales/1,000 km of effort), and varied by season, year, and distribution zone. In addition, nearly 5,700 fish schools were recorded with fish presence highest during summer and fall.

Capture-recapture abundance and survival estimates of three cetacean species in Icelandic coastal waters using trained scientist-volunteers

Interspecific relationships in density among a whale community in Antarctic feeding grounds were examined using the sightings data derived from the systematic surveys conducted between 1978/1979 and 1987/1988. A clear difference in densities against the physiographic variables (the sea floor-slope type) was identified between baleen whales and toothed whales. Densities of sperm whales and ziphiids were low in the waters over the continental shelf where minke whales' densities were highest. This led to an apparent negative correlation in the density between minke and sperm whales, and minke whale and ziphiids. A significant positive correlation in density between minke and blue whales was identified. No association in density between minke and humpback whales was observed. Distribution of killer whales shows strong positive correlation with that of minke whales. The positive correlation existed between minke and blue whales, and minke and killer whales even when the effect of environmental variables was excluded. Analysis also revealed that the environmental variables, including physiographic variables, are major factors affecting the distributions and density of whales, especially between baleen whales and toothed 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.

Controlled exposure experiments using 1 to2 kHz sonar signals were conducted with 11 humpback whales (Megaptera novaeangliae), one minke whale (Balaenoptera acutorostrata), and one northern bottlenose whale (Hyperoodon ampullatus) during three field trials from 2011 to 2013. Ship approaches without sonar transmis-sions, playbacks of killer whale vocalizations, and broadband noise were conducted as controls. Behavioural parameters such as horizontal movement, diving, social interactions, and vocalizations were recorded by animal-attached tags and by visual and acoustic tracking. Based on these data, two expert panels independently scored the severity of behavioural changes that were judged likely to be responses to the experimental stimuli, using a severity scale ranging from no effect (0) to high potential to affect vital rates (9) if exposed repeatedly. After scoring, consensus was reached with a third-party moderator. In humpback whales, killer whale playbacks induced more severe responses than sonar exposure, and both sonar exposures and killer whale playbacks induced more responses and responses of higher severity than the no-sonar ship approaches and broadband noise playbacks. The most common response during sonar exposures in all three species was avoidance of the sound source. The most severe responses to sonar (severity 8) were progressive high-speed avoidance by the minke whale and long-term area avoidance by the bottlenose whale. Other severe responses included prolonged avoidance and cessation of feeding (severity 7). The minke whale and bottlenose whale started avoiding the source at a received sound pressure level (SPL) of 146 and 130 dB re 1 μPa, respectively. Humpback whales generally had less severe responses that were triggered at higher received levels. The probability of severity scores with the potential to affect vital rates increased with increasing sound exposure level (SEL). The single experiments with minke and bottlenose whales suggest they have greater susceptibility to sonar disturbance than humpback whales, but additional studies are needed to confirm this result.

Abundance, trends and distribution of baleen whales off Western Alaska and the central Aleutian Islands

Whale song

An aerial line transect survey of whales in West and East Greenland was conducted in August-September 2015. The survey covered the area between the coast of West Greenland and offshore (up to 100 km) to the shelf break and in East Greenland from the coast up to 50 km offshore crossing the shelf break. A total of 423 sightings of 12 cetacean species were obtained and abundance estimates were developed for common minke whale, (Balaenoptera acutorostrata), fin whale (Balaenoptera physalus), humpback whale (Megaptera novaeangliae), harbour porpoise (Phocoena phocoena), long-finned pilot whale, (Globicephala melas) and white-beaked dolphin (Lagenorhynchus albirostri). The estimates were corrected for perception bias and availability bias where possible. Data on surface corrections for minke whales and harbour porpoises were collected from whales instrumented with satellite-linked time-depth-recorders. Options for estimation methods are presented and the preferred estimates are: minke whales: 5,095 (95% CI: 2,171-11,961) in West Greenland and 2,762 (95% CI: 1,160-6,574) in East Greenland, fin whales: 2,215 (95% CI: 1,017-4,823) in West Greenland and 6,440 (95% CI: 3,901-10,632) in East Greenland, humpback whales: 993 (95% CI: 434-2,272) in West Greenland and 4,223 (95% CI: 1,845-9,666) in East Greenland, harbour porpoises: 83,321 (95% CI: 43,377-160,047) in West Greenland and 1,642 (95% CI: 319-8,464) in East Greenland, pilot whales: 9,190 (95% CI: 3,635-23,234) in West Greenland and 258 (95% CI: 50-1,354) in East Greenland, white-beaked dolphins 15,261 (95% CI: 7,048-33,046) in West Greenland and 11,889 (95% CI: 4,710-30,008) in East Greenland. The abundance of cetaceans in coastal areas of East Greenland has not been estimated before, but the limited historical information indicates that the achieved abundance estimates were remarkably high. Comparing the estimates from 2015 in West Greenland with a similar survey conducted in 2007, there is a trend towards lower densities in 2015 for the baleen whale species and white-beaked dolphins. Harbour porpoises and pilot whales, however, did not show a similar decline. The decline in baleen whale and white-beaked dolphin abundance is likely due to emigration to the East Greenland shelf areas where recent climate driven changes in pelagic productivity may have accelerated favourable conditions for these species.

Field observations of cue rates for common minke whales, fin whales and humpback whales were conducted in July 1996 and MaySeptember 2006. The cue for minke whales was usually the dorsal ridge breaking the water surface. A total of 295min of surfacings of five minke whales ranging 27-106min were observed and the simple mean was 46.1 surfacings per hour (CV=0.11). The cue for fin and humpback whale surfacings was sometimes the head breaking the surface but most often a blow. Twenty-three trials of fin whale groups ranging 1-4 individuals provided 620min of observations. The simple mean of all the trials was 52 blows hr–1 (CV=0.06). When trials &lt;10min were excluded the surfacing rate remained unchanged, but when trials &lt;30min were excluded the surfacing decreased to 50 blows hr–1 (CV=0.07, n=8 trials). A total of 860min (n=39 trials) and 1,232 blows from surfacing humpback whales were collected from groups of 1-4 individuals. The simple mean of all trials was 71 blows hr–1 (CV=0.07). The minke, fin and humpback whale cue rate estimates are close to values obtained from other studies, but they are the first that are specific to West Greenland and it is suggested that they should be used for correcting abundance estimates obtained from the aerial cue counting method.

Cetaceans of the Atlantic Frontier, north and west of Scotland

Different species of baleen whales display distinct spatial distribution patterns in the Scotia Sea during the austral summer. Passive acoustic and visual surveys for baleen whales were conducted aboard the RRS James Clark Ross in the Scotia Sea and around South Georgia in January and February 2003. Identified calls from four species were recorded during the acoustic survey including southern right (Eubalaena australis), blue (Balaenoptera musculus), fin (B. physalus) and humpback whales (Megaptera novaeangliae). These acoustic data included up calls made by southern right whales, downswept D and tonal calls by blue whales, two possible types of fin whale downswept calls and humpback whale moans and grunts. Visual detections included southern right, fin, humpback and Antarctic minke whales (B. bonaerensis sp.). Most acoustic and visual detections occurred either around South Georgia (southern right and humpback whales) or south of the southern boundary of the Antarctic Circumpolar Current (ACC) and along the outer edge of the ice pack (southern right, blue, humpback and Antarctic minke whales). Fin whales were the exception, being the only species acoustically and visually detected primarily in the central Scotia Sea, along the southern ACC front. In addition to identifiable calls from these species, two types of probable baleen whale calls were detected: 50Hz upswept and pulsing calls. It is proposed that minke whales may produce the pulsing calls, based on their similarities with minke whale calls recorded in the North Atlantic Ocean. There was an overlap between locations of fin whale sightings and recordings and locations of 50Hz upswept calls in the central Scotia Sea, but these calls were most similar to calls attributed to blue whales in other parts of Antarctica. More study is required to determine if baleen whales produce these two call types, and if so, which species. The efficiency of acoustics and visual surveys varied by species, with blue whales being easier to detect using acoustics, Antarctic minke whales being best detected during visual surveys and other species falling in between these two extremes.

Entanglement in static fishing gear (pots, or creels as they are called in Scottish fisheries) is a major cause of anthropogenic mortality and morbidity in large whales globally; in northeastern Atlantic waters around the coast of Scotland, entanglement is a particular welfare and conservation concern for minke whales Balaenoptera acutorostrata and humpback whales Megaptera novaeangliae. Reports from strandings, live disentanglements and interviews with Scottish inshore creel fishers were gathered to estimate entanglement rates. Considerably more whale entanglements occur in the Scottish creel fishery than previously thought based on strandings alone, with estimates of 6 humpback whales and 30 minke whales becoming entangled each year. Where entanglement type was reported, 83% of minke and 50% of humpback whales were caught in groundlines between creels. There was a positive correlation between the average amount of gear set by a vessel and the number of minke whale entanglements. For the west coast of Scotland, the estimated annual fatal entanglement rate of minke whales is 2.3% of a recent abundance estimate, suggesting a risk of localised depletion. There are very low densities of humpback whales in Scottish waters, but opportunistic observations suggest numbers are increasing. The estimated number of annual humpback whale entanglements also shows an increasing trend. There are few entanglement estimates for static pot fisheries globally; this study provides an indication of how such data might be derived. Scottish creel fishers have shown a willingness to engage in entanglement mitigation, with suggestions such as the introduction of sinking groundline to the sector, and these options should be urgently pursued.