Sei Whale (Balaenoptera borealis) Research Proposal
Numerous cetacean species are still recovering from commercial whaling. Some populations show encouraging signs of recovery (e.g., North Pacific humpback whales; COSEWIC 2011) since the ban on commercial whaling in 1986 under the International Whaling Commission moratorium. However, some countries have continued harvesting wild cetaceans either for research purposes, commercial hunt or subsistence harvest. Impacts on cetaceans from marine anthropogenic activities remains a prominent issue (Weilgart 2007, Rolland et al. 2012, Trumble et al. 2018), slowing down the recovery of several iconic species in Canada, notably the North-Atlantic right whale, southern resident killer whale and the St. Lawrence Estuary Beluga (Krahn et al. 2002, Pace et al. 2017, Lesage 2021). For several species of rorqual whales, and understanding of basic biological parameters such as population size, demographic structure and year-round distribution, remains challenging, partially due to their pelagic distribution and generally smaller population sizes (Prieto et al. 2012).
Previously assessed as a data deficient species, the Atlantic Sei whale population in Canada was reclassified as endangered in 2019 due to a presumably small population size – primarily as a result of intense commercial whaling and slower-than-expected recovery. Less than 1000 mature individuals are estimated to frequent the pelagic waters off Nova Scotia, Newfoundland and Labrador (predominantly along the continental shelf), from March to October (Davis et al. 2020). Like many cetaceans, Sei whales face multiple anthropogenic threats, such as noise from oil and gas exploration, ship strike and entanglement (COSWEIC 2019). Stranding records indicate that the primary cause of mortality for Sei whales is ship strike and entanglement in fishing gear (COSEWIC 2019). Oil and gas exploration within predicted Sei whale habitat (offshore waters off Canada’s East Coast) has intensified since 2015 and is suspected to be a detrimental source of underwater noise (COSEWIC 2019); however lethal and sublethal effects from exposure to acute and chronic noise is much harder to evaluate, especially in remote offshore areas. An understanding of basic Sei whale biology, ecology, and habitat requirements in Canada is currently lacking. Implementation of a science-based approach to support protection and management of this endangered species and its habitat is proposed below.
The following proposal aims to address some of the knowledge gaps identified in the COSEWIC (2019) report on the Atlantic Population of Sei whales in Canada. The proposed research project would contribute to the assessment of Sei whale abundance and distribution, critical habitat, as well as threats. This information would constitute an important baseline to support conservation efforts and management of this understudied species, particularly in a rapidly changing environment influenced by climate change and ever-present anthropogenic threats.
A preliminary vessel-based research survey will be conducted during the summer months. This will be considered a pilot study to evaluate if sei whale aggregation can be found of eastern Canada and what kind of data can be reliably collected in offshore waters. If this first survey is deemed successful, subsequent surveys will be conducted to collect adequate data. Long-lived and hard-to-access species often require multi-year studies in order to generate adequate sample size and to capture any natural variation. Most of the survey work will be carried out from a 41’ sailing vessel. Weather permitting, a small rigid-hulled inflatable vessel will be deployed from the sailing vessel to facilitate close approaches for certain types of data collection.
Transects will be designed according to the current best available knowledge on Sei whale occurrence. Daytime visual transects with hydrophone deployments at intervals informed from detection range modelling will be conducted from Newfoundland eastern continental shelf edge to and within the Labrador Sea, overlapping with areas where Sei whale acoustic detections clusters have been identified between 2015 and 2017 off eastern Canada (Delarue et al. 2018). Hydrophone deployments will be used to increase the probability of detections, particularly during periods of reduced visibility. Once Sei whales are detected either visually or acoustically, individuals will be approached to obtain photographs for identification and to collect biopsy samples. Aerial images will also be taken from sampled individuals with a remotely piloted aircraft system (RPAS). Opportunistic fecal samples will be collected whenever possible. Depending on funding and logistics, this project would also have the expertise required to deploy satellite tags to better understand longer-term movements patterns. Lastly, to contribute to Sei whale habitat characterization, a conductivity-temperature-depth (CTD) cast will be deployed following each Sei whale encounter.
The following data could be collected during these surveys and would contribute to filling the several data gaps related to abundance and distribution, critical habitat, and threats:
1. Photo-identification data
a. Will provide data for abundance estimates and inter-annual frequentation
b. Will be used to quantify the proportion of individuals bearing scars from entanglement and ship strike
c. Will be used to investigate movement patterns between different regions
d. Can be collated with other opportunistic sightings databases (whale watching, open sources catalogs such as “Happy Whale”) and other research cruises to increase sample size and spatio-temporal coverage; could also be useful to study migration patterns by comparing photo-ID catalogs from different regions; for instance, previous studies have revealed movements from the Azores to Canadian waters (Olsen et al. 2009).
2. Acoustic data
a. will help identify areas occupied by Sei whales particularly when visual detection is not possible; although this data collection will cover a relatively small temporal scale, it benefits from a large spatial scale, covering areas not sampled by current and past deployment of bottom mounted hydrophones
3. Biopsy samples
a. will be used for genetics analysis to better understand genetic variability and population structure
b. estimate demographic parameters such as the proportion of females and males
c. can be used to assess diet using stable isotopes and fatty acid signatures
d. hormone analyses can be conducted on the blubber to assess stress, pregnancy rates, reproductive status
4. Satellite and/or GPS tag data
a. will contribute to our understanding of spatial and temporal patterns of Sei whale movement and distribution
b. assist in localizing foraging areas
c. can be linked to other environmental parameters (e.g. bathymetry, distance from shore, depth, slope, sea surface temperature) to better characterize habitats of importance
d. Can be linked to presence/distance to nearby seismic surveys
5. CTD casts
a. will help characterize physical parameters of habitats used by Sei whales
6. Aerial imagery
a. documentation and quantification of the prevalence of entanglement and ship strike as a threat (via scar analysis)
b. measurements for baseline morphology estimates, as well as assessment of body condition
7. Opportunistic fecal sample collection
a. can provide information on diet
b. can be used to extract sexual and/or stress-related hormones
The pelagic nature of Sei whale will make it difficult to locate and follow individuals. Therefore, this research project is designed to maximize data collection opportunities that have the potential to contribute to various research questions and collaborations. Furthermore, data collected during research cruises could be combined with current available data on Sei whales to increase sample size.
COSEWIC. (2011). COSEWIC assessment and status report on the Humpback whale (Megatpetera Novaengliae) North Pacific Population in Canada. Ottawa, Canada: Committee on the Status of Endangered Wildlife in Canada.
COSEWIC. (2019). COSEWIC assessment and status report on the sei whale (Balaenoptera borealis) Atlantic Population in Canada. Ottawa, Canada: Committee on the Status of Endangered Wildlife in Canada.
Davis GE, Baumgartner MF, Corkeron PJ, Bell J, Berchok C, Bonnell JM, Bort Thornton J, Brault S, Buchanan GA, Cholewiak DM, Clark CW. Exploring movement patterns and changing distributions of baleen whales in the western North Atlantic using a decade of passive acoustic data. Global change biology. 2020 Sep;26(9):4812-40.
Delarue, J., K.A. Kowarski, E.E. Maxner, J.T. MacDonnell, and S.B. Martin. 2018. Acoustic Monitoring Along Canada’s East Coast: August 2015 to July 2017. Document Number 01279, Environmental Studies Research Funds Report Number 215, Version 1.0. Technical report by JASCO Applied Sciences for Environmental Studies Research Fund, Dartmouth, NS, Canada. 120 pp + appendices.
Krahn MM, Wade PR, Kalinowski ST, Dahlheim ME, Taylor BL, Hanson MB, Ylitalo GM, Angliss RP, Stein JE, Waples RS. Status review of southern resident killer whales (Orcinus orca) under the Endangered Species Act.
Lesage V. The challenges of a small population exposed to multiple anthropogenic stressors and a changing climate: the St. Lawrence Estuary beluga. Polar Research. 2021 Sep 3;40.
Pace III RM, Corkeron PJ, Kraus SD. State–space mark–recapture estimates reveal a recent decline in abundance of North Atlantic right whales. Ecology and Evolution. 2017 Nov;7(21):8730-41.
Prieto R, Janiger D, Silva MA, Waring GT, Goncalves JM. The forgotten whale: a bibliometric analysis and literature review of the North Atlantic sei whale Balaenoptera borealis. Mammal Review. 2012 Jul 1;42(3):235.
Ramp C, Gaspard D, Gavrilchuk K, Unger M, Schleimer A, Delarue J, Landry S, Sears R. Up in the air: drone images reveal underestimation of entanglement rates in large rorqual whales. Endangered Species Research. 2021 Jan 28;44:33-44.
Rolland RM, Parks SE, Hunt KE, Castellote M, Corkeron PJ, Nowacek DP, Wasser SK, Kraus SD. Evidence that ship noise increases stress in right whales. Proceedings of the Royal Society B: Biological Sciences. 2012 Jun 22;279(1737):2363-8.
Trumble SJ, Norman SA, Crain DD, Mansouri F, Winfield ZC, Sabin R, Potter CW, Gabriele CM, Usenko S. Baleen whale cortisol levels reveal a physiological response to 20th century whaling. Nature communications. 2018 Nov 2;9(1):1-8.
Weilgart LS. The impacts of anthropogenic ocean noise on cetaceans and implications for management. Canadian journal of zoology. 2007 Nov;85(11):1091-116.