In addition to our regular photo-Id and biopsy-based population structure and behavioural studies of baleen whales in the Gulf of St Lawrence, we collaborate with several other research institutions and universities research projects involving acoustics, genetics, and foraging behaviour.
Sensory and Foraging Ecology in Baleen Whales - René Swift (University of St Andrews, Scotland)
René Swift, a PhD student at the University of St Andrews (Scotland), is currently undertaking a project to investigate the sensory and foraging ecology of baleen whales. Baleen whales, some of the largest animals to have lived on the planet, successfully feed on some of the smallest and most abundant prey, such as krill and forage fish. We still do not know how baleen whales detect and locate their prey. Unlike for toothed cetaceans the wave-lengths of sounds produced by baleen whales appear to be too large to detect small targets. Thus it would seem that baleen whales have evolved another method to effectively detect prey. The cues used to detect prey may include environmental signals, such as thermal fronts, and acoustic or chemical signals produced by the prey. To investigate these questions, non-invasive camera and accelerometer tags (data loggers that were designed and developed at the University of Tokyo, Japan) are attached by suction cup to humpback and fin whales. The whales are followed for the duration of the tag attachment (between 8 - 10 hours), with simultaneous surveys of the prey field, using the camera tag on the animal, and a hull mounted echo-sounder aboard the research vessel. This allows us to observe the whale's foraging movements in relation to prey density and distribution. During a preliminary study conducted in 2011, using these methods, Mr. Swift was able to confirm for the first time, that Gulf of St. Lawrence humpback whales switched from foraging in the water column to foraging on the seabed. During the coming fourth field season for this project, the focus will shift to fin whales, in order to compare the species. The data collect for nearly 30 humpback whales tagged over the last three seasons will require considerable time to analyze.
Trophic Niche Partitioning among Rorquals in the Gulf of St. Lawrence
In collaboration with Fisheries and Oceans (DFO) Canada, we are investigating trophic niche partitioning among the four sympatric rorquals species in the Gulf of St Lawrence using stable isotopes in the skin of the whales. In resource-limited environments, competition for food sources is potentially greatest among closely-related species with similar ecological requirements such as the blue, fin, humpback and minke whales all found in the Gulf of St Lawrence. However, there is a general lack of information regarding their ecological niches, which limits our comprehension of mechanisms facilitating their coexistence. So far we have found that blue whales occupied the lowest relative trophic position, followed by fin, minke and humpback whales. In addition, an evaluation of long-term resource use patterns revealed, that species with specialized diets (blue whales) effectively had the lowest degree of temporal dietary variation, whereas species known to have broader diets (fin, humpback and minke whales) showed dietary fluctuations over time. This temporal variation in resource use, particularly in humpback whales, may be a response to shifts in prey abundance or availability. Stable isotopes can also be used to monitor large environmental changes over time and we will continue to monitor the diet of the whales in the St. Lawrence.
Measuring Reproductive and Stress Hormones in Humpback Whales - Sea Mammal Research Unit, Scotland.
In an on-going project in collaboration with researchers at the Sea Mammal Research Unit of the University of St. Andrews (Scotland), the levels of reproductive and stress hormones are measured in blubber biopsy samples and blow samples collected from humpback whales. Reproductive hormone levels, particularly progesterone, have been measured in cetacean blubber samples and blow samples as indicators of pregnancy in various cetacean species. Other studies have shown, that high progesterone levels are indicative of pregnancy. Therefore, we can collect information on pregnancy rates in our humpback whale population, as well as, calf survival rates, when females are seen the following season with or without a calf.
In the same matrices, the blubber and the blow, the stress hormone cortisol will also be measured. In their natural environment, animals experience a variety of environmental and anthropogenically influenced conditions, which can induce a physiological stress response. Stress responses can be short-term (acute) or long-term (chronic), and because of potentially harmful effects of chronic stress on various aspects of animal physiology, including immune function and reproductive output, there is a growing interest in measuring stress in wild animals. This study will attempt to understand how to measure stress in free-ranging whales, cortisol in blubber biopsy samples will be analysed as an indicator of chronic stress, while cortisol levels in the blow will be analysed as an indicator of acute stress.
Reproduction and body condition of humpback whales
Jo Kershaw, a first year PhD student at the University of St Andrews and member of the MICS team, is currently undertaking a collaborative project between the two research institutes to investigate novel ways of measuring the body condition of free-ranging whales. The body condition of individuals is a measure of their fat reserves, and is a good predictor of their resilience to potential environmental fluctuations and anthropogenic impacts, and also of their reproductive health and potential. Despite its importance, current methods of estimating the body condition of free ranging cetaceans are descriptive, subjective or inapplicable to most species. Jo will address this gap in our ability to measure cetacean body condition by investigating and validating novel, robust methods of estimating the condition of free ranging cetaceans using biomarkers in their blubber. Cetaceans are unique among mammal species in that their fat reserves can be sampled directly through biopsy sampling of their blubber layer. As such, cetacean blubber presents an excellent opportunity for minimally invasive sampling to gain insight into the condition of live animals. Therefore, this work aims to develop methods of estimating the body condition of cetaceans using both the types and quantities of fats and hormones in their blubber as biomarkers of overall condition.
Satellite Tagging Project
In order to gather more detailed information on blue whale movements in the St Lawrence we deployed our first satellite tags in 1996. This effort yielded 12 and 19 days of tracking data in the St Lawrence Estuary. In 2002 we tagged a single blue whale, and tracked its dispersal from the Estuary out into the Gulf of St Lawrence and East of the Magdalene Islands for just over a month.
In 2010 a more regular blue whale tagging program, using low-penetration tags was implemented in the St Lawrence Estuary and off the eastern tip of Gaspe Peninsula, which resulted in 19 tag deployments. The satellite tagging data has confirmed and expanded on the data collected through photo-ID since the 80s, that had revealed that blue whales regularly disperse east and west along the Gaspé Peninsula from spring to late fall. Photo-ID and satellite tag data now confirms that dispersal occurs from the St Lawrence to Cabot Strait and beyond in the fall.
This collaborative tagging program with Dr. Lessage of Department of Fisheries (DFO) in Mont-Joli, QC, will be pursued in 2014 and will enable us to increase our knowledge of blue whale habitat use in eastern Canadian waters.