By: Lamin Komma, Marine Biologist
All plant and animal life forms are included from the microscopic picoplankton all the way to the majestic blue whale, the largest creature in the sea – and for that matter in the world. Life in the ocean has been a subject of attraction for many years. One of the most significant reasons for the study of ocean life is simply to understand the world in which we live. Research indicates that oceans cover 71% (and still rising due to climate change impacts) of this world, and yet we have only scratched the surface when it comes to understanding them. Scientists estimate that no more than 5% of the oceans have been explored, hitherto, we need to understand the marine environment that helps support life on this planet and this can be done through basic and applied research in order to help governments, universities, civil society organizations, and businesses find real-world solutions to specific problems while also increasing their output and productivity.
Our well-being depends on a healthy ocean. It always has and will always be. Its importance cannot be over-emphasized because everything that we rely on in our day-to-day lives leads back to them. Oceans feed us, regulate our climate and generate most of the oxygen we breathe.
Notwithstanding their significance, oceans are facing unprecedented threats due to anthropogenic (human) activities. It is studied that yearly, an estimated 8 million tonnes of plastic waste end up in the world’s oceans and at the same time, climate change is damaging this ecosystem; overfishing is threatening the stability of fish stocks; nutrient pollution is contributing to the creation of dead zones; and nearly 80% of the world’s wastewater is discharged without treatment. For this reason, UN Environment is tackling these challenges by working with stakeholders to promote the protection and sustainable management of our precious but fragile marine and coastal ecosystems in order to achieve the 2030 Sustainable Development Agenda, particularly Goal 14, Life Below Water.
In the Gambia, our territorial sea extends to 12nm with an Exclusive Economic Zone (EEZ) extending to 200nm. The seas off the Gambia are located where two major oceanic currents converge along the coast of West Africa. One is the highly productive upwelling zone of the Canary Current Large Marine Ecosystem (CCLME) which is cold and nutrient rich water flowing southward. The other is the eastward-flowing warm Guinea current. The effects of these currents together with the trade winds which blow dominantly from the Sahara Desert westerly out over the Atlantic create intermittent upwelling along the coast of The Gambia. These upwelling, combined with the discharge of the Gambia River provide the nutrients that fuel a bountiful marine ecosystem.
Recently, a dead whale was washed ashore along the northern coastline of the country between Barra and Jinack Island. The death of the whale washed ashore is indicative of the state of our marine environment and its potential to support life. Who knows how many marine mammals would die in the short and/or long term.
However, as a country, what do we know about this enigmatic and fascinating creature, its appearance, distribution, biology and ecology, threats and conservation? As a marine biologist, I will help the readers to unlock the secret.
What are whales?
In general terms, whales are marine mammals, belonging to the cetacean family. Their relatives include dolphins and porpoises which are precious not only as tourist attraction but also play an important role in marine food chain. They give birth to live young that stay with the mother for over a year and feed on milk produced by the mother.
Cetaceans are divided into two groups: toothed and baleen whales. Toothed whales have teeth with one opening at their blowhole. So far, records have shown that there are 73 species of toothed whales including sperm whales, killer whales and beaked whales, belugas and narwhals, porpoises and dolphins. On the other hand, baleen whales have two blowholes and instead of teeth, they have many rows of baleen plates (“whalebone”) which are made of keratin.
There are different species of baleen whales including the Blue Whale (Balaenoptera musculus), (the largest animal ever to have lived on earth), Humpback whale (Megaptera novaeangliae), Antarctic Minke whale (Balaenoptera bonaerensis), Fin whale (Balaenoptera physalus), Sei whale (Balaenoptera borealis), Bryde’s whale (Balaenoptera edeni) and the 3 species of Right whales.
So which whale species was washed ashore?
According to the reports by the staff of Department of Parks and Wildlife Management (DPWM) stationed at Nuimi National Park, the species was a Bryde’s whale, measuring 15.10m and a width of 7.92m.
A brief description, distribution, behavior, diet and reproduction of Bryde’s whale
Bryde’s whales are one of the most poorly understood whales of the baleen family. They are considered as one of the “great whales” together with blue and humpback whales respectively. They are found in both tropical and temperate waters of Atlantic, Indian and Pacific oceans due to their preference for waters of 16°C or higher. They can also be seen in both nearshore and open waters between the latitudes of 40° South and 40° North. They are native to many countries and territories including The Gambia.
Studies have indicated that this whale eats an estimated 500 to 600 kg of food daily, feeding more on pelagic schooling fish but also preys on krill and other crustaceans in areas of high productivity. During feeding, this whale use diverse methods to feed in the water column, ranging from skimming the surface, lunging to creating bubble nets.
Reproductively, this species becomes sexually matured at around 9 years and can mate all year round. The peak of breeding and calving season occurs in autumn (September to November) and females produce one calf every two years. The gestation period is 11 months and the calves stay with their mothers feeding on milk until they are weaned at 6 to 7 months.
The population of this species is exposed to a variety of threats which can be categorized under natural and human induced threats. With regard to natural threats, it is presumed that only killer whales would prey on these whales and their calves as there is no reliable information on natural predators. However, ship strikes and entanglements in fishing gears are among the human induced threats of Bryde’s whale.
There exist an International Whaling Commission which comprise two antagonistic blocs – the American side which comprised most developed countries (e.g. USA, Canada, Australia, New Zealand, England etc.) and the Japanese side which comprised most developing countries (headed by Japan) and Gambia is a signatory to this commission.
The bone of contention between the two blocs surrounds their conservation and exploitation of whales. The developed bloc advocates to promote conservation of whale, therefore restricting the killing of whales. However, the developing bloc and Japan are advocating for the rational exploitation of the whales. The former argue that whales are important tourist attraction (whale watching) and therefore, in order to promote tourism, whales must be conserved. The latter bloc argue that whales are contributing to the depletion of world fish stock. Fisheries is an important natural resource base for most developing countries, hence, the rational exploitation and to reduce the whole population.
Nonetheless, as of 2018, this species is considered a species of Least Concern on the International Union for the Conservation of Nature (IUCN) Redlist of threatened species. It is also listed on Appendix II of the Convention on Migratory Species (CMS) and Appendix I of Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES).
- The government should work towards laying foundation to establish research laboratory that would address issues relating to fisheries and environment
- The skeletons of the whale to be exhumed and preserved for future academic and school learning process
- Develop human resources to independently conduct research
- Further strengthen the trans-boundary maritime cooperation within the region especially the Cooperation of the Contracting Parties in the Protection, Management and Development of Marine and Coastal Environment of West, Central and Southern African region (Abidjan Convention)
- A closer-to-home scenario is to foster a stronger trans-boundary cooperation between Gambia and Senegal in the areas of basic and applied marine research mentioned above.