Cetaceans as ‘change ambassadors’

Cetaceans were chosen as our guides for the Seafood Free September project because of their universal appeal to humanity. We respond to cetaceans on an emotional, visceral, and even primal level, in ways that science has attempted to measure, understand and describe.

Encounters with cetaceans are, for many people, an uplifting experience. Being in their presence may simply reflect our own inherent capacity for joy, yet our emotional reactions have enormous value, and may inspire us collectively to act on behalf of a worthy cause.

The Seafood Free September campaign focuses on the environmental impacts of industrial fishing on cetaceans, not only because of the vital role they play in marine ecosystems, but because they are sentient beings deserving of life in a quiet, safe and clean ocean.

Cetaceans are ecosystem engineers, are sentinel species for ocean health, may potentially capture and store massive amounts of carbon, and are highly intelligent, self-aware, culturally complex, social beings.

Cetaceans as ‘ecosystem engineers’

All marine organisms have a role to play in maintaining a healthy ocean. Cetaceans are both the stars and supporting cast in various marine systems and processes. Fish are critical elements in marine food webs and chains. Seafood, including squid, krill and invertebrates, and many species of finfish, shellfish and flatfish, are major components in the diets of cetaceans. Cetaceans are predators, and prey to sharks and other whales.

A scientific paper (Roman et al. 2014) that synthesised decades of research on the ecological role of the ‘great whales’ – the mysticetes (baleen whales) and the larger odontocete Physeter macrocephalus (Sperm Whale), concluded that recovery of whale populations could lead to increased productivity in high-latitude areas (feeding grounds) and less productive, low-latitude, equatorial areas (calving grounds), which may support more robust fisheries.

This conclusion lends scientific support to the establishment of Important Marine Mammal Areas (IMMAs) in the feeding grounds, nurseries and migratory routes of cetaceans.

The paper demonstrated how whales act as ecosystem engineers in the ocean when they die and their carcasses ‘fall’ to the seafloor, providing organic material to nutrient- and energy-poor environments, and habitat for deep-sea species. Large whales store, transfer and recycle nutrients, enhancing primary productivity however, their contribution is relatively small.

Phytoplankton are the primary producers in the ocean, requiring sufficient levels of carbon dioxide, iron, nitrogen and phosphorous for photosynthesis. The upwelling that transfers the cold, nutrient-rich water to the surface enables this primary production to occur. The baleen whale Balaenoptera musculus (Blue Whale) may contribute to primary production where iron is a limiting factor, for example, in the Southern Ocean (Lavery et al. 2014).

Cetaceans as ‘sentinel species’

Cetaceans may act as sentinel species for ocean, environmental and human health by measuring and tracking their responses to ecological changes, anthropogenic pollutants and destructive fishing practices (see Gillnet Fishing & Vaquita Porpoises under Impacts).

Top predator Tursiops truncatus (Bottlenose Dolphin) bioaccumulate contaminants in their blubber, are long-lived cetacean species residing long-term in coastal areas, including bays and estuaries (Wells et al. 2004), and are ideal study specimens for environmental health.

Blubber samples from four stranded Orcinus orca (Killer Whale) in Ireland between 2010 and 2017 found high levels of 43 types of persistent organic pollutants (POPs), exceeding recommended thresholds for these contaminants (Schlingermann et al. 2020).

In contrast, blubber and muscle samples were taken from 71 male Balaena mysticetus (Bowhead Whale) landed in Alaska between 2006 and 2015. Tissue analysis for persistent organic pollutants (POPs) indicated lower concentrations of most substances than those reported in samples collected between 1992 and 2000 (Bolton et al. 2020).

Cetaceans as ‘carbon sequestrators’

Cetaceans have enormous potential to capture and store massive amounts of carbon, removing it from the global atmosphere and re-distributing it through marine food chains. Large whales may play a role in regulating and stabilising the temperature of the planet and could be a major force in climate change management.

A study on the impact of whaling on the ocean carbon cycle on eight species groups of baleen whales (Pershing et al. 2010) found that large whale populations store over 9 million tons less carbon than they did prior to the whaling industry. Whales transfer nearly 30,000 tons of carbon to the deep ocean floor when they die as ‘whale fall’. Recovery of whale populations to their pre-commercial whaling size would increase this carbon sink to 160,000 tons.

It may be economically worthwhile to protect cetaceans for carbon capture, climate change mitigation purposes, ecotourism and building strong coastal economies. Economists have attempted to place a dollar value on cetaceans, estimating an individual whale to be worth about $2 million over its lifetime. Restoring whale populations to pre-commercial whaling numbers (between 4,000,000 and 5,000,000 individuals) could capture 1.7 billion tons of carbon annually (Chami et al. 2019).

Cetaceans as ‘sentient beings’

Decades of scientific research has shown cetaceans to be highly intelligent marine mammals with large, complex brains capable of sophisticated language and communication, with the ability to form co-operative social structures, use tools and learn new behaviours.

Cetaceans are cultural beings, displaying characteristics that are passed down generations, including social behaviour and communication strategies through language and song.

Research into self-awareness in Tursiops truncatus (Bottlenose Dolphin) have demonstrated that this cetacean species, when given a mark test, will investigate the location of the mark on their body using a mirror (Reiss & Marino 2001), and can recognise their reflected self as early as seven months of age (Morrison & Reiss 2018).

A 32-year study of 1,647 Delphinapterus leucas (Beluga Whale) between 1978 and 2010 used data from migratory patterns and genetic studies to locate and track close beluga relatives from year to year, and across decades, to see if beluga whales returning to their birthplace or early environment was an inherited behaviour.

The researchers concluded that beluga whale relatives returned to the same locations across years and generations, with mothers passing along knowledge of navigation strategies, migratory routes and social learning to their calves, building beluga culture (O’Corry-Crowe et al. 2018).

© 2016 – 2022 Seafood Free September.

REFERENCES:

Jennie L. Bolton, Gina M. Ylitalo, Paul Chittaro, J. Craig George, Robert Suydam, Brian T. Person, Jonelle B. Gates, Keri A. Baugh, Todd Sformo, Raphaela Stimmelmayr, Multi-year assessment (2006–2015) of persistent organic pollutant concentrations in blubber and muscle from Western Arctic bowhead whales (Balaena mysticetus), North Slope, Alaska, Marine Pollution Bulletin, Volume 151, 2020, 110857, ISSN 0025-326X, https://doi.org/10.1016/j.marpolbul.2019.110857

Ralph Chami, Thomas Cosimano, Connel Fullenkamp, and Sena Oztosun, Nature’s Solution to Climate Change: A strategy to protect whales can limit greenhouse gases and global warming, Finance & Development, December 2019, Volume 56, No. 4, https://www.imf.org/external/pubs/ft/fandd/2019/12/natures-solution-to-climate-change-chami.htm, accessed 06.07.2021

Morrison R, Reiss D (2018) Precocious development of self-awareness in dolphins. PLOS ONE 13(1): e0189813. https://doi.org/10.1371/journal.pone.0189813

O’Corry-Crowe G, Suydam R, Quakenbush L, Potgieter B, Harwood L, et al. (2018) Migratory culture, population structure and stock identity in North Pacific beluga whales (Delphinapterus leucas). PLOS ONE 13(3): e0194201. https://doi.org/10.1371/journal.pone.0194201

Pershing AJ, Christensen LB, Record NR, Sherwood GD, Stetson PB (2010) The Impact of Whaling on the Ocean Carbon Cycle: Why Bigger Was Better. PLOS ONE 5(8): e12444, https://doi.org/10.1371/journal.pone.0012444

Reiss, Diana & Marino, Lori., Mirror self-recognition in the bottlenose dolphin: A case of cognitive convergence. Proceedings of the National Academy of Sciences May 2001, 98 (10) 5937-5942; https://doi.org/10.1073/pnas.101086398

Joe Roman, James A Estes, Lyne Morissette, Craig Smith, Daniel Costa, James McCarthy, JB Nation, Stephen Nicol, Andrew Pershing, Victor Smetacek. Whales as marine ecosystem engineers. Frontiers in Ecology and the Environment, 2014; 140703070154008, https://doi.org/10.1890/130220

Schlingermann, Moira, Berrow, Simon, Craig, Darren, McHugh, Brendan, Marrinan, Michael, O’Brien, Joanne, O’Connor, Ian, Mudzatsi, Engelberth, White, Philip, High concentrations of persistent organic pollutants in adult killer whales (Orcinus orca) and a foetus stranded in Ireland, Marine Pollution Bulletin, Volume 151, 2020, 110699, ISSN 0025-326X, https://doi.org/10.1016/j.marpolbul.2019.110699

Wells, R.S., Rhinehart, H.L., Hansen, L.J. et al. Bottlenose Dolphins as Marine Ecosystem Sentinels: Developing a Health Monitoring System. EcoHealth 1, 246–254 (2004). https://doi.org/10.1007/s10393-004-0094-6