Bryde's whale

Distribution

Bryde’s whales are also  known as ‘tropical whales’, due their apparent preference for waters above 16°Celcius and concentration in latitudes between 40° south and 40° north. Although some seasonal movement between warmer and colder waters has been documented for some populations, others have been observed to reside year-round in coastal tropical or sub-tropical waters^4,5. They can be found both inshore and offshore, and tend to be associated with areas of high productivity, such as upwelling areas.

Bryde's whales are native to the following countries and territories: American Samoa; Angola; Anguilla; Antigua and Barbuda; Argentina; Aruba; Australia; Bahamas; Bahrain; Bangladesh; Barbados; Belize; Benin; Bermuda; Bonaire, Sint Eustatius and Saba (Saba, Sint Eustatius); Brazil; Cambodia; Cameroon; Cape Verde; Cayman Islands; Chile; China; Cocos (Keeling) Islands; Colombia; Comoros; Congo; Congo, The Democratic Republic of the; Cook Islands; Costa Rica; Côte d'Ivoire; Cuba; Curaçao; Djibouti; Dominica; Dominican Republic; Ecuador; El Salvador; Equatorial Guinea; Eritrea; Fiji; French Guiana; French Polynesia; Gabon; Gambia; Ghana; Gibraltar; Grenada; Guadeloupe; Guam; Guatemala; Guinea; Guinea-Bissau; Guyana; Haiti; Honduras; India; Indonesia; Iran, Islamic Republic of; Iraq; Jamaica; Japan; Kenya; Kiribati; Korea, Democratic People's Republic of; Korea, Republic of; Kuwait; Liberia; Madagascar; Malaysia; Maldives; Marshall Islands; Martinique; Mauritania; Mauritius; Mexico; Micronesia, Federated States of ; Morocco; Mozambique; Myanmar; Namibia; Nauru; New Caledonia; New Zealand; Nicaragua; Nigeria; Niue; Northern Mariana Islands; Oman; Pakistan; Palau; Panama; Papua New Guinea; Peru; Philippines; Pitcairn; Puerto Rico; Qatar; Réunion; Saint Kitts and Nevis; Saint Lucia; Saint Martin (French part); Saint Vincent and the Grenadines; Samoa; Sao Tomé and Principe; Saudi Arabia; Senegal; Seychelles; Sierra Leone; Singapore; Sint Maarten (Dutch part); Solomon Islands; South Africa; Sri Lanka; Taiwan, Province of China; Tanzania, United Republic of; Thailand; Timor-Leste; Togo; Tonga; Trinidad and Tobago; Turks and Caicos Islands; Tuvalu; United Arab Emirates; United States; Uruguay; Vanuatu; Venezuela, Bolivarian Republic of; Viet Nam; Virgin Islands, British; Virgin Islands, U.S.; Wallis and Futuna; Western Sahara; Yemen.

Biology and Ecology

Feeding

Bryde’s whales predominantly feed on schooling fish (including sardines, anchovies, mackerels and herrings), but they have also been documented to prey on crustaceans like krill, copepods or pelagic red crabs.  Even squid remains have been detected in some Bryde’s whale stomach contents^4,6. They are typically associated with tropical or subtropical  areas of unusually high productivity – such as the upwelling areas off the coast of Brazil⁷, South Africa^8,9, and the in the Arabian Sea^10-12.   Like humpback whales, they are active lunge feeders, and can be observed bursting through a dense school of fish with a gaping mouth and throat pleats extended.  Feeding events often involve multiple other species, such as gannets, common dolphins, seals and sharks¹³.

Social Structure Reproduction and growth

Bryde’s whales are typically seen alone or in groups of no more than three, although larger aggregations of up to 20 can be observed in prime feeding areas.  Whaling data show that in some offshore populations of Bryde’s whales conception and calving appeared to take place in winter months.  However, inshore populations of Bryde’s whales in South Africa did not show any seasonal restrictions in their mating and calving⁶.  Gestation lasts roughly 11 months, and calves are thought to remain with their mothers until they are weaned at 6-7 months⁶.   Like minke whales, Bryde’s whales appear to be able to proudce one calf every two  years.^4,6

Threats and conservation status

Natural Predators

There is no reliable information on natural predators of Bryde’s whales, although it is presumed that, as for other baleen whales, only killer whales would be large enough and strong enough to prey on these whales and their calves.

Human induced threats

Since the cessation of commercial whaling, there is very little information on current threats to Bryde’s whales.  Ship strikes and entanglement in fishing gear are likely to affect this species to some degree, with documented incidents in the Arabian Sea¹² and South Africa¹⁴.  Purse seine fisheries for tuna have also been documented to set their nets on Bryde’s whales, which are likely to be feeding on the same small schooling fish that attract tuna. Whether or not this association leads to significant levels of mortality is unknown^15,16.  Inshore populations are inherently at risk due to their small population size and low genetic diversity. E.g. Gulf of Mexico population¹⁷, South African inshore population¹⁴.

Conservation status

Bryde’s whales were not heavily targeted for commercial whaling, due partly to their mostly tropical distribution outside of the most common whaling grounds in higher latitudes, and partly due to the fact that they were smaller and less appetizing or lucrative than larger species that yielded more oil and meat. As a consequence, most Bryde’s whale stocks are believed to be relatively intact, although the long-standing confusion between species may mean that some of the catches recorded as sei whales may actually have been Bryde’s whales.  A limited number of Bryde’s whale catches are still conducted in the northwest Pacific each year by Japan who left the IWC in 2019.

The historical confusion between Bryde’s and sei whales, which makes pre- and post-whaling population numbers difficult to estimate, combined with the continued lack of clarity regarding the taxonomic status of Bryde’s whale populations around the world has led to a Data Deficient classification on the IUCN Redlist of threatened species.  The species is listed on Appendix II of the Convention on Migratory Species (CMS) and Appendix I of CITES.

Bryde’s whales and whale watching

Please see the IWC Whalewatching Handbook