When the Whales Came Back (2020)

by Lucía Caldas

It is probably fair to say that 2020 hasn’t been the best year for humans… but this has not been the case for many wild animal species. We have witnessed a large number of events that showed how quickly wildlife can claim their ground back¹ when humans are not going about their usual business.¹

One such case is that of many cetacean species visiting the Atlantic waters off the North-West coast of Spain (namely Galicia) in numbers unprecedented since whaling was banned in 1985. Among others, 20 fin whales and 9 blue whales were seen feeding together on September 6^th!²

But why here? What is so special about this place for the largest mammals on our planet? This area undergoes seasonal upwelling events driven by northerly winds³ typically occurring in spring and summer, which cause cold, nutrient-rich waters to rise to the photic layer where primary production is enhanced. This in turn brings many zooplankton species (such as krill) to feed on all these primary producers, and that is just what the whales want! But not only whales benefit from this, fish-eaters like dolphins and porpoises also benefit, as many fish species such as bluefin tuna are drawn to these areas chasing the abundant smaller fish that feed on the zooplankton. Unfortunately, upwelling regions like this are under threat from climate change so it is crucial to understand how large marine mammals can adapt.⁴ 

[Area of focus for photo-ID of a blue whale]

There are different technological devices used to study the distribution⁵, social structure⁶ and hunting strategies⁷ of these magnificent sea creatures. Drones are extremely useful for spotting marine mammals during transect flights, while hand-held cameras allow for individual photo-ID⁸. Pole cameras help record their movements and behaviour underwater, while hydrophones are used to gather data on communication and to assess the noise levels underwater⁹. This allows further insight on the acoustic disturbances they face. Satellites are useful as well to record migratory routes of these marine giants¹⁰. Once all this data is collected, software like Ecopath with Ecosim (EwE) and GIS programs (among others) are used to analyse population dynamics as well as habitat distribution and preferences^3,5. The subsequent results provide invaluable data for further development of policies and management strategies.

Cetaceans in this area are studied mainly by the Bottlenose Dolphin Research Institute (BDRI)¹¹, established in Galicia in 2014. They have taken part in the Balaenatur Project during 2020, which focused on studying the presence of blue, fin and sei whales in Galician waters. Right up until then, 2017 had been the year with the most sightings of different cetacean species, but as the chart shows, these numbers have been greatly surpassed! Sightings of fin whales (B. physalus), blue whales (B. musculus) and minke whales (B. acutorostrata) have been much higher in 2020.

But exactly how many cetaceans have been seen this past year? The preliminary results on baleen whales (mysticetes) published on October 21^st are quite impressive.

[Evolution of baleen whale sightings 2017 – 2020]

A total of 235 individuals were spotted in 99 total sightings, comprised of 61 sightings of fin whales (186 individuals), 20 sightings of blue whales (30 individuals) and 18 sightings of minke whales (19 individuals)!¹²

The 21^st of October 2020 was an important date, as it marked the 35^th anniversary of the last whale hunted in Galician waters¹², a 17-metre female fin whale^12,13.

Among the species of toothed whales (odontocetes) we find some impressive numbers as well.

70 porpoises¹⁴, 207 groups of common dolphins (7100+ individuals)¹⁵, 216 sightings of groups of bottlenose dolphins (almost 3 groups each day)¹⁶, a group of Risso’s dolphins with a touching story¹⁷ (follow the link) and… ORCAS!

A pod of orcas made the news in the summer¹⁸ when they gave some sailors a scare!¹⁹ These giant dolphins are no strangers to Galician waters, as they migrate through the area every year chasing bluefin tuna and other fish species²⁰, but they usually don’t attract this much attention!

But what does all this mean for us? Why should we care?

It can be difficult to measure the true value of biodiversity. Ecologists attempt to do this by assigning monetary value to ecosystem services. These magnificent marine mammals are keystone and indicator species. This means that the ecosystem is healthy when they are present.

The benefits they provide include the fertilization of the ocean and the reduction of the effects of climate change. They do this by enhancing the development of primary producers (which capture CO₂ and in turn benefit both fisheries and aquaculture) with their poo!²¹ Their presence can also generate benefits through tourism. All this considered, the potential value of having whales in this specific area amounts to 276 million euros!²²

These are some of the reasons why it is so important to study these animals and develop sustainable strategies for the management of fisheries, aquaculture and boat traffic. All these factors pose a big threat to these species and can play a major role in the protection of these long-lived marine mammals who keep our oceans healthy.

Thanks to the BDRI for sharing the information used to inform this blogpost. 

References

1. https://www.bloomberg.com/news/photo-essays/2020-04-08/with-humans-in-hiding-animals-take-back-the-pandemic-world 
2. https://www.lavozdegalicia.es/noticia/arousa/2020/09/05/ciencia-constata-mayor-avistamiento-grandes-cetaceos-rias-baixas/0003_202009A5C6991.htm
3. https://www.researchgate.net/publication/339704497_Food-web_interactions_in_a_coastal_ecosystem_influenced_by_upwelling_and_terrestrial_runoff_off_North-West_Spain
4. https://www.researchgate.net/publication/332622285_Habitat_drivers_of_endangered_rorqual_whales_in_a_highly_impacted_upwelling_region?fbclid=IwAR13NP6ngLau8wHX7oEoUViS0VsVkZfXPkXTjIHTBMSQxEMUiTfGqHi9Jb8
5. https://www.researchgate.net/publication/333519880_Modelling_common_dolphin_Delphinus_delphis_coastal_distribution_and_habitat_use_Insights_for_conservation?fbclid=IwAR1OfGEWbZZiDOnatBifB3G9GvZKwtz7ISNdhZccX-RN91v34twXqviYo5M
6. https://www.sciencedirect.com/science/article/abs/pii/S0003347220300610?via%3Dihub
7. https://www.researchgate.net/publication/262232948_The_bottlenose_dolphin_Tursiops_truncatus_foraging_around_a_fish_farm_Effects_of_prey_abundance_on_dolphins'_behavior?fbclid=IwAR19HTt_x71CLTaXs_gKNynuwmaMvU-X-sZYBrvjr6MbBWO5FZyz7jjQAJc
8. https://www.facebook.com/thebdri/photos/a.76387242330/10157185130402331/
9. https://www.facebook.com/thebdri/videos/1340928326255948 
10. https://www.bbc.co.uk/news/extra/buqvasp1rr/orcas-spain-portugal
11. https://www.thebdri.com/
12. https://fb.watch/2Vg_Wwfj0g/
13. https://www.lavozdegalicia.es/noticia/arousa/o-grove/2020/10/24/bm-003-gal-ballena-azul-tres-anos-17-metros-veranea-rias/0003_202010A24C5992.htm?fbclid=IwAR21NjFoq8k63thu8TMjqalz2j0nGZ1MXMiyXTp4gjaBrQHSFUQnbpHBnn4
14. https://www.facebook.com/thebdri/photos/a.76387242330/10157146592467331/
15. https://www.facebook.com/thebdri/photos/a.76387242330/10157362826812331/
16. https://www.facebook.com/thebdri/photos/a.76387242330/10157359700072331
17. https://www.facebook.com/thebdri/photos/a.76387242330/10157151503582331/
18. https://www.theguardian.com/environment/2020/sep/01/boats-off-spain-damaged-in-orca-encounters
19. https://www.theguardian.com/environment/2020/sep/24/they-were-having-a-real-go-scottish-man-recounts-orca-attack
20. https://www.theguardian.com/environment/2020/oct/06/previous-incident-may-have-led-orcas-to-target-boats-say-experts-spain-portugal
21. https://www.npr.org/templates/story/story.php?storyId=130437080&t=1610492364836 
22. https://www.facebook.com/thebdri/photos/pcb.10157306931677331/10157305612832331/