Baleen and sperm whales, known collectively as the great whales, include the largest animals in the history of life on Earth. With high metabolic demands and large populations, whales probably had a strong influence on marine ecosystems before the advent of industrial whaling: as consumers of fish and invertebrates; as prey to other large-bodied predators; as reservoirs and vertical and horizontal vectors for nutrients; and as detrital sources of energy and habitat in the deep sea. The decline in great whale numbers, estimated to be at least 66% and perhaps as high as 90%, has likely altered the structure and function of the oceans, but recovery is possible and in many cases is already underway.
Future changes in the structure and function of the world’s oceans can be expected with the restoration of great whale populations. Marine biologists are hoping that the recovery in whale numbers may well help to offset the effect of “destabilising stresses” on the ocean, including rising temperatures and acidification occurring as a result of climate change.
IN A NUTSHELL
- Commercial whaling dramatically reduced the biomass and abundance of great whales and, until recently, we have lacked the ability to study and directly observe the functional roles of whales in marine ecosystems
- Whales facilitate the transfer of nutrients by releasing fecal plumes near the surface after feeding at depth and by moving nutrients from highly productive, high-latitude feeding areas to low-latitude calving areas
- Whale carcasses sequester carbon to the deep sea, where they provide habitat and food for many endemic invertebrates
- The continued recovery of great whales may help to buffer marine ecosystems from destabilizing stresses and could lead to higher rates of productivity in locations where whales aggregate to feed and give birth