Researchers from the Canary Islands Oceanographic Center (IEO/CSIC) and the University of La Laguna (ULL) warned this Thursday that ship collisions with sperm whales are leading the population of this cetacean species in the Canary Islands to local extinction.
In a letter sent to the media, researchers Natacha Aguilar (IEO/CSIC) and Marc Solá (ULL) pointed out that the last two sperm whale deaths in recent days "show that this serious problem continues", after the stranding of a female of only 9 meters and the appearance adrift of a juvenile male.
In the case of the female, it is likely that she "only reproduced once, or not at all, before being run over", while in the case of the second specimen, its size suggests "that it will not have the opportunity to contribute to the recovery of the population", the experts detailed.
In this sense, they lamented that in the Canary Islands "too many have already been lost" specimens and have pointed out that the latest studies show a "catastrophic" decline, with a reduction by half in the abundance of sperm whales in the Canary Islands.
They also recalled that a female sperm whale will only have about 10 offspring in her life and that she invests a great effort in each one: more than a year of gestation (14-16 months to give birth to a calf of about 4 meters in length, several years of lactation and even more time of guidance, until the young males leave the maternal family group at about 10 years of age.
"Although they can move hundreds or even up to four thousand kilometers in search of food, they have spatial fidelity to their native territory. The males will mature solitary in cold waters and will join the matrilineal clans only in migratory reproduction trips, when they reach about 30 years of age", the researchers detailed.
Thus, they indicated that these numbers reflect a vital biological history "not so different from the human one" and that, in addition, in these very close social groups, the loss of an individual is much more than a number, because "a link in the social structure is lost, with meaning and transcendence".
"The sperm whale is an animal that breaks many records: the largest predator in the ocean, the one that emits the most powerful sounds to echolocate its prey at a distance in the dark immensity of the deep waters, the largest nose on the planet (necessary to be able to emit its powerful echolocation clicks), the largest brain in the animal world... Despite this large brain, they have not yet learned to avoid collisions with ships", the scientists lamented.
For Aguilar and Solá it does not make sense that if humans put speed limits on traffic in inhabited areas, in the ocean, however, the speed limit is set by technology.
"In less than the life of a sperm whale - about 70 years - the speed of ships has more than doubled and the number of ships that transit their habitat has increased by more than 100% - in some areas 300% -. Sperm whales need to rest on the surface to perform their diving feats, and if they interrupt their rest every time they hear a ship, they would not be able to recover strength to hunt in dives that can reach almost 3 kilometers deep and more than two hours in duration, in apnea", the experts added.
Therefore, throughout their lives they have been forced to get used to enduring close passes of ships "until one of those passes is too close and costs them their lives".
"They have not had evolutionary time to modify their behavior, because human changes are too fast, and we have filled the oceans with high-speed highways in a sperm whale generation", they warned.
Finally, they recalled that the Canary Islands is an important enclave for the sperm whale in the Northeast Atlantic, as it reproduces and family groups are found in all seasons, with individuals recognized over the years.
"Although the sperm whale inhabits all the oceans of the world, its global abundance is decreasing, and in some places, such as the Canary Islands, the decline is plummeting. Are we willing to make changes as a society to safeguard the sperm whale in the Canary Islands?", the researchers concluded.