History of Dolphin in Timeline
Dolphins are aquatic mammals belonging to the Odontoceti clade. They are classified into five families: Delphinidae, Platanistidae, Iniidae, Pontoporiidae, and potentially the extinct Lipotidae. There are currently 40 recognized species of dolphins.
1933: Discovery of Hybrid Dolphins
In 1933, three hybrid dolphins, a cross between Risso's and bottlenose dolphins, were found beached off the Irish coast. This discovery marked an early instance of recognizing hybridization between these dolphin species.
1962: Queensland's Shark Culling Program Initiated
In 1962, Queensland, Australia, implemented a controversial shark culling program aimed at reducing shark attacks. This program, employing methods such as shark nets and drum lines, has faced criticism for its significant bycatch, resulting in the unintended deaths of thousands of marine animals, including dolphins.
1976: Rise in Orca Captivity
Between 1976 and 1997, there was a significant increase in capturing orcas for display in aquariums and aquatic theme parks, with 55 whales taken from Iceland, 19 from Japan, and three from Argentina.
1976: Poole's Coat of Arms Depicts Naturalistic Dolphin
In 1976, the town of Poole, Dorset, England, updated its coat of arms, changing the depiction of the dolphin from a stylized heraldic form to a more naturalistic representation.
1982: El Niño Event Impacts Dolphin Populations
The El Niño warming event of 1982-83 had cascading effects on marine ecosystems, including impacting dolphin populations. The event caused shifts in prey distribution, leading to changes in the ranging patterns of various dolphin species, highlighting the interconnectedness of marine food webs and the influence of climate variability.
1984: Pacific White-Sided Dolphin Occurrence Increases on Canada's West Coast
Between 1984 and 1998, a noticeable increase in the occurrence of Pacific white-sided dolphins was observed along the western coast of Canada. This shift in distribution patterns may be attributed to various factors, including changes in prey availability or oceanographic conditions, potentially linked to climate change.
1985: Birth of the First Wolphin
The first recorded wolphin, a hybrid offspring of a false killer whale and a bottlenose dolphin, was born in captivity in 1985 at the Sea Life Park in Hawaii. This event garnered significant attention and sparked interest in the possibilities and implications of cetacean hybridization.
1988: Billie the Dolphin Learns and Spreads Tail-Walking
In 1988, a female dolphin named Billie, after spending time with captive dolphins, learned and began performing tail-walking in the Port River. This marked the beginning of a cultural phenomenon within the dolphin community, showcasing their capacity for social learning and the spread of novel behaviors.
1991: Tilikum's First Fatal Incident
The first documented fatal incident involving Tilikum, a captive orca, occured in 1991.
1992: Dolphin Range Shifts in Northwest Europe
From 1992 to 2003, shifts in dolphin ranges were observed in northwest Europe, with warm-water species like the short-beaked common and striped dolphins expanding north, potentially displacing white-beaked and Atlantic white-sided dolphins.
1992: Tilikum Moved to SeaWorld
In 1992, Tilikum, a captive orca, was moved to SeaWorld.
1994: Fatal Dolphin Attack in Brazil
In 1994, a man died off the coast of Brazil after being attacked by Tião, a bottlenose dolphin known to have been harassed by humans.
1995: Dolphin Self-Awareness Study Using Television
In 1995, Marten and Psarakos conducted a study using television to investigate self-awareness in dolphins. They presented dolphins with real-time videos of themselves, other dolphins, and recorded footage. While the study's findings, which suggested self-awareness, have been debated, they spurred further research into dolphin cognition and self-recognition.
1996: First Fraser's Dolphin Recorded in the UK
In 1996, a Fraser's dolphin, typically found in tropical waters, was recorded in the UK for the first time.
1997: Decline of Wild Orca Captures
By 1997, the capture of wild orcas for captivity began to decline.
1998: End of Observation Period for Increased Pacific White-Sided Dolphin Occurrence
By 1998, the period of increased observation of Pacific white-sided dolphins on the west coast of Canada, which began in 1984, concluded. This marked the end of a period of notable presence for the species in the region, with potential implications for understanding long-term population trends and the influence of environmental factors.
1999: Rise of Captive-Born Orcas
By 1999, approximately 40% of the 48 orcas on display globally were captive-born, marking a shift from wild captures.
1999: Tilikum's Second Fatal Incident
The second documented fatal incident involving Tilikum, a captive orca, occured in 1999.
2000: Alleged Sale of Military Dolphins
In 2000, reports emerged claiming that the Russian Navy had sold dolphins, trained for military purposes during the Soviet era, to Iran, sparking controversy and raising concerns about the ethical implications of using animals in warfare.
2003: Dolphin Range Shifts in Northwest Europe
By 2003, the increase of common dolphins and decrease of white-beaked dolphins in northwest Scotland indicated a shift in dolphin populations, likely influenced by warming waters.
2003: Short-beaked Common Dolphin Subpopulation Endangered
In 2003, the short-beaked common dolphin subpopulation in the Mediterranean was declared endangered due to a decline in prey resources caused by rising sea surface temperatures, increased salinity, intensified upwelling, and rising sea levels.
May 2005: Discovery of Tool Use and Cultural Transmission in Dolphins
A groundbreaking discovery in May 2005 revealed that Indo-Pacific bottlenose dolphins in Australia teach their offspring to use tools. This behavior, observed as dolphins protecting their snouts with sponges while foraging, provided compelling evidence of cultural transmission and learning within dolphin communities.
2005: Dolphin-Assisted Therapy Study and Criticism
A 2005 study suggested dolphins could be an effective treatment for mild to moderate depression, but it was criticized for methodological flaws and lack of comparison to other therapies, raising questions about the validity of dolphin-assisted therapy (DAT).
October 2006: Discovery of Dolphin with Pronounced Vestigial Hind Limbs
In October 2006, a bottlenose dolphin with unusually prominent fins near its genital slit was caught in Japan. Scientists believe these fins to be a significant development of vestigial hind limbs, offering a glimpse into the evolutionary history of dolphins and their transition to aquatic life.
2006: Yangtze River Dolphin Declared Functionally Extinct
Tragically, in 2006, a comprehensive survey failed to find any surviving individuals of the Yangtze river dolphin. This marked a devastating loss for biodiversity and highlighted the severe threats faced by many cetacean species, particularly those inhabiting freshwater environments. The Yangtze river dolphin was subsequently declared functionally extinct.
2007: Long-Term Study on Dolphin Shelling Behavior Begins
A long-term research project spanning from 2007 to 2018 in Shark Bay, Australia, focused on observing and documenting the "shelling" behavior in dolphins. This complex foraging technique, involving trapping fish in large conch shells, provided insights into dolphin ingenuity, social learning, and cultural transmission across generations.
2007: Discovery of Spindle Neurons in Dolphins
Prior to 2007, elongated spindle neurons, linked to advanced cognitive functions such as social behavior and emotions, were thought to be unique to hominids. In 2007, these neurons were discovered in the neocortex of several dolphin species, suggesting parallels in cognitive abilities and social complexity between dolphins and humans.
2009: Discovery of Dolphin Wall Painting in Iklaina
During excavations in 2009, a wall painting fragment depicting a ship with humans and dolphins was discovered in the Mycenaean city of Iklaina, adding to the evidence of dolphins' significance in ancient Greek culture.
2010: Tilikum's Third Fatal Incident
The third documented fatal incident involving Tilikum, a captive orca, occured in 2010, further fueling the debate on keeping orcas in captivity.
2011: Marine Heatwave Impacts Dolphin Population in Western Australia
A 2011 marine heatwave in Western Australia's Shark Bay World Heritage Area caused a significant decline in the local Indo-Pacific bottlenose dolphin population due to decreased prey availability, impacting dolphin reproductive rates.
2011: Increase in Tail-Walking Dolphins Observed
By 2011, the number of dolphins observed tail-walking in the Port River had significantly increased, with up to 12 individuals displaying this learned behavior. Interestingly, the skill appeared to be primarily adopted by female dolphins, suggesting potential gender-specific patterns in social learning within this dolphin community.
2014: Continued Impact of Queensland's Shark Culling Program on Dolphins
As of 2014, Queensland's long-standing shark culling program, initiated in 1962, has resulted in the deaths of at least 32 dolphins, adding to the growing concern over the program's unintended consequences for non-target marine species. The program's use of indiscriminate methods continues to raise ethical and ecological concerns.
2017: Orcas in Captivity
As of 2017, there were 60 orcas held in captivity at aquariums, a small number compared to bottlenose dolphins, highlighting the growing ethical concerns surrounding orca captivity.
2017: Death of Tilikum
Tilikum, an orca involved in three fatal incidents with humans, died in captivity in 2017.
2018: Completion of Long-Term Study on Dolphin Shelling Behavior
In 2018, a long-term research project that began in 2007, dedicated to understanding the "shelling" technique employed by dolphins in Shark Bay, Australia, concluded. The study's findings offered valuable insights into the transmission of this intricate foraging behavior, revealing a pattern of knowledge transfer primarily within generations, challenging previous assumptions about mother-to-offspring learning in dolphins.
2018: Study on the Spread of Tail-Walking in Dolphins Published
In 2018, a study by Mike Rossley et al. was published, focusing on the intriguing phenomenon of tail-walking behavior spreading among dolphins. The study aimed to shed light on the reasons behind the adoption and persistence of this energy-consuming behavior, which appears to provide no apparent benefits in terms of survival or foraging success.
October 2021: Extended Tail-Walking Session Observed
In October 2021, a dolphin in the Port River was observed engaging in an unusually long tail-walking session, lasting for several hours. This observation fueled ongoing research and fascination with the purpose and motivation behind this seemingly energy-intensive behavior, which appears to offer no direct survival advantage.