User:YellowstoneLimestone/Sandbox2

Background
Orcas exist across the world's oceans but vary greatly in their foraging strategies, behavior, and ecology. In 197xxx, the orcas off the Pacific northwest were divided into "transient" and "resident" categories. At the time, resident whales were thought to remain in the same areas, while transients frequently moved long distances. Resident orcas stayed in large pods and ate fish and transient whale traveled in small pods and targetted marine mammals. Additional research revealed that both types expressed site fidelity and had large ranges. Regardless, the naming convention continued, and the two have been recognized as unique ecotypes. The ecotype label has since been applied to several populations of killer whales, often based on feeding strategy and morphology. An offshore ecotype has been described for whales that live off the coastal shelf in the North Pacific. Orcas in the North Atlantic have been described as either Type 1 or Type 2 ecotypes, though the author initially proposing this dichotomy has since suggested retiring it.

https://www.researchgate.net/profile/Andrew-Scullion-5/publication/354418921_Scottish_Killer_Whale_Photo_Identification_Catalogue_2021/links/613776a72b40ec7d8bf0c522/Scottish-Killer-Whale-Photo-Identification-Catalogue-2021.pdf http://whitelab.biology.dal.ca/rwb/kwstatus2001.pdf https://academic.oup.com/beheco/article/23/2/246/244676

Orcas in the Antarctic region are divided into five ecotypes: Type A, Type B1, Type B2, Type C, and Type D. Type B1 and Type B2 were initially considered a singular Type B, but divided based on morphologic and ecological differences. (Morphological and ecological evidence for two sympatric forms of Type B killer whale around the Antarctic Peninsula) Types A, B1, B2, and C are known to make short-term migrations to warmer waters in South America, Australia, and New Zealand. Due to the short trip duration, lack of foraging activity, high-speed linear travel, and observations of calves in Antarctic waters, Pitman et al. (2019) posited that Types C, B1, and B2 were not traveling to warmer waters to feed or calve. Instead, the ecotypes migrated to lower latitudes because the warmer waters were more conducive to skin molting, thereby removing the diatom buildup. https://onlinelibrary.wiley.com/doi/pdfdirect/10.1111/mms.12661

https://www.researchgate.net/profile/Josh-Mcinnes/publication/351606391_The_First_Records_of_Antarctic_Type_B_and_C_Killer_Whales_Orcinus_orca_in_Australian_Coastal_Waters/links/60e1022ba6fdccb745037f6b/The-First-Records-of-Antarctic-Type-B-and-C-Killer-Whales-Orcinus-orca-in-Australian-Coastal-Waters.pdf

While the ecotype model has been largely accepted for killer whales, it may not always adequately describe the nuances of populations and demographics. Additionally, there is not a globally accepted methodology for determining ecotype.

A genetic analysis of several ecotypes and populations supported the division for many ecotypes, with suggestions some of them warranted subspecies or species status. Resident and transient orcas diverged approximately xxxx years ago. Genetic analyses have suggested that they may constitute unique species or subspecies. Types A, B1, B2, and C, despite their clear morphological differences, are genetically similar. However, another analysis suggested that Types B (prior to being splits) and C should be considered separate species. Type D's diverged approximately xxxxx years ago and may also constitute of unique species.

Resident
In the Russian Far East, resident- and transient-like orca populations have been identified Analysis of orcas from Academia Gulf, Avacha Gulf, Karaginsky Gulf, and Kamchatka Peninsula showed reproductive isolation of sympatric resident-type ("R-type") and transient-type ("T-type") whales. The two types also exhibit differences in saddle patch shape. R-type whales are most common in the deep coastal waters of eastern Kamchatka, the Commander Islands, and the Kuril Islands. T-types are more predominant in Chukchi Peninsula and the coastal Okhotsk Sea, where waters are shallow and develop ice cover in winter. In the Kuril Islands, the R-type form is predominant in summer. T-types have occasionally been observed, including a pod that had previously been identified near Chyornye Bratya. Japanese orcas are also known to migrate to the Kuril Islands.

The Russian fish- and mammal-eating populations are genetically related to their Pacific northwest (PNW) counterparts.

Offshore
Movements and Diving Behavior of the Eastern North Pacific Offshore Killer Whale (Orcinus orca). Front

North Atlantic
Foote et al. (2009) proposed two ecotypes in the North Atlantic: a generalist Type 1, which feeds mostly on Atlantic herring and occasionally on marine mammals, and Type 2, specialists that prey on marine mammals. Of locations sampled, Type 1 was found from Newfoundland to Norway. Type 2 was found in Scotland and the Faroe Islands, though were possibly more widespread. Morphologic and genetic differences between the two were described, with emphasis on tooth wear; Type 1 were identified as having more tooth wear. Type 1 specimens were up to 6.6 meters long, while Type 2 animals were up to 8.5 meters in length. However, Foote has since recommended retiring the terminology until more research is undertaken, particularly in remote areas, as it may not accurately describe the population dynamics and demographics in the region. Supporting this suggestion, a study in fatty acid signatures across several orca populations in the North Atlantic found that diet composition varied greatly at the individual level even within the same populations. In a study of Norwegian killer whales, animals were classified as "fish-eaters" or "seal-eaters" based on field observations and isotope analysis. Fish-eaters displayed a preference for fish and tended to move offshore to open waters. Seal-eaters consumed fish and seal depending on prey availability, and ten

Satellite-tagged "seal-eaters" moved alongside the coast while "fish-eaters" tended toward open ocean. Additionaly, seal-eaters

No ecotypes have been recognized in the western North Atlantic or Canadian Arctic.

United Kingdom whales; John Coe; Shetland whales https://www.researchgate.net/publication/258506913_Using_opportunistic_photo-identifications_to_detect_a_population_decline_of_killer_whales_Orcinus_orca_in_British_and_Irish_waters https://repository.uantwerpen.be/docman/irua/ee8b77/157588_2019_07_01.pdf https://www.int-res.com/articles/ab2015/24/b024p075.pdf

Type C
Type C orcas, also referred to as Ross Sea killer whales, are the smallest recognized ecotype. On average, adult females reach 5.2 m in length while adult males reach 5.6 m. Type C orcas are gray and white, with a dark grey dorsal cape spanning from the front of the eye patch to just behind the dorsal fin. They have narrow eye patches that slant forward at a 45°. This ecotype often appears slightly yellow due to a diatom film; the diatom species Bennettella ceticola has been identified on skin biopsies from Type C whales. Type C whales typically eat fish, with isotope analysis suggesting that Antarctic toothfish (Dissostichus mawsoni) makes up a significant portion of their diet. They have also been observed displaying hunting behavior around penguins.

Type C orcas are found near the Antarctic peninsula, being particularly abundant in the Ross Sea, but make short-term migrations north. The ecotype has been photographed in both New Zealand and southeastern Australian waters; one female in particular has been photographed in both New Zealand and McMurdo Sound over the course of several years. Departure times ranged from late January to mid-March, depending on tagging location, and round-trip migrations lasted an estimated 41.6 to 55.6 days. One tagged Type C animal's round trip distance was approximately 11,000 km. Tagged individuals were identified at the tagging location the next year, indicating possible site fidelity. Furthermore, in winter 1995, a group of Type C orcas were photographed within the Antarctic pack ice, suggesting that Type C whales may overwinter in Antarctica.

Migrating Type C orcas did not dive as deeply as they did at their feeding grounds and did not display overt foraging activities.

In 1983, Soviet scientists described a small form of killer whale that ate fish and lived in pack ice. They proposed Orcinus glacialis as a species name. It is possible that O. glacialis and Type C orcas are the same animal, but difficult to ascertain, as Type B animals inhabit the same area and specimens taken by the Soviet scientists have since been discarded.

Type D
Type D orcas, also referred to as Subantarctic killer whales, are the rarest ecotype. They have a very small eye patch, bulbous head, and pointed, swept back dorsal fin. Type D whales have been observed taking Patagonian toothfish (Dissostichus eleginoides) from longlines, suggesting fish may be a typical part of their diet. Goup size of Type D whales range from nine to 35 based on limited at-sea sightings. While the ecotype has been identified near islands, it is mostly observed in deep, open ocean. Type D orcas inhabit the subantarctic zone circumglobally, but sighting suggest that they are only found between 46°S and 62°S latitudinally.

Two strandings of Type D whales have been documented. In 1955, a mass stranding of killer whales, identified from photographs as Type D whales decades later, occurred in New Zealand. In 2022, nine animals stranded in Magellan Strait, Chile. Analysis of the 2022 whales suggested that Type D orcas may be physically smaller and have smaller teeth than other ecotypes. Additionally, Type D orcas have been studied and cataloged near Crozet Island, where their range overlaps a "regular" Crozet type. Both ecotypes depredate off of longline fisheries, but they have not been observed associating, even when interacting with the same fishing vessel.

Foote (2013) et al. compared DNA from a museum specimen collected at the 1955 stranding to other ecotypes. They found a high level of divergence, with Type D whales having diverged from other populations approximately 390,000 years ago. As such, they may constitute a unique subspecies or species. A later genomic analysis of multiple Type D whales showed a low effective population size indicative of a population bottleneck, and "among the highest level of inbreeding reported for any mammalian species."

Other populations
Many orca populations have not been studied extensively and lack rigorous research on their behavior and phylogeny. As such, more ecotypes may exist. However, as there is no global model of what constitutes an orca ecotype, an ecotype label may be ascribed on varying bases such as behavior, range, and morphology. Some orca populations are occasionally referred to as ecotypes despite not being widely described as such. Lastly, pre-existing ecotype models (namely, the transient, resident, and offshore forms) are sometimes applied to other populations that exhibit similar feeding strategies.

Argentina
The orcas of Punta Norte have been referred to as an ecotype. These whales have a distinct hunting style, in which they intentionally strand themselves to catch sea lion pups. https://sistema.editoraartemis.com.br/index.php/admin/api/artigoPDF/32175

Australia and New Zealand
While orca populations (besides visiting Antarctic forms) exist in Australian waters, they have not been well studied. Orcas appear to congregate seasonally in at least two areas: the inshore Ningaloo Reef area and the offshore Bremer Sub-Basin area. These populations are referred to as northwestern Australia (NWA) and southwestern Australia (SWA) whales, respectively. While only 26 NWA animals have been identified, over 140 SWA animals have been cataloged. Australian orcas have been observed preying on cetaceans, teleosts, sharks, and cephalopods. In southeastern Australia, orcas depredate blue-eye trevalla longline fisheries. Genetic analysis suggests that the NWA population is more closely related to tropical orcas, while the SWA whales are more related to Southern Ocean orcas. NWA and SWA may represent different ecotypes, but there is limited research into these populations' morphology, behavior, and general ecology. ^^^^^^^^^^^^^^^^^^^^get sources

In New Zealand, two behaviorally distinct subpopulations have been described as ecotypes: an inshore coastal form that mainly consumes elasmobranchs and an offshore pelagic form that mainly consumes cetaceans. These proposed ecotypes also display differences in eye patch and dorsal fin morphology. Current genetic research supports that the New Zealand, NWA, and SWA orcas represent unique populations. However, there is low genetic diversity among the NZ whales and a subpopulation division is not currently supported. In Morin (2010)'s phylogenetic analysis of orca populations, the sole New Zealand whale clustered with Eastern North Atlantic Type 1. Additionally, orcas sampled off of Chatham Island showed distinct ancestry compared to mainland New Zealand whales.https://repositorio.ul.pt/bitstream/10451/45965/1/Foote%20et%20al.%202019%20accepted.pdf

Crozet Islands
The Crozet orca popultion inhabits the inshore and offshore waters near the Crozet Islands, sympatric with the offshore Type D ecotype. The Crozet form has been referred to as an ecotype, morphotype, and a "regular" form to distinguish it from the Type D whales. Crozet whales are genetically distinct from Type D whales and may be more closely related to the Type A form. Crozet whales are generalists, having been observed feeding on fish, birds, pinnipeds, and cetaceans. They are also known to depredate Patagonian toothfish longline fisheries. In 2020, the Crozet population was approximately 89 to 94 individuals, with 19 active matrilineal social groups averaging 3 to 4 animals. The Corzet population experienced a sharp decline in the 1990s due to firearms and explosives used by IUU fisheries. The population still has a high mortality rate, possibly due to lethal interactions with fisheries.

Eastern Tropical Pacific
While the Eastern North Pacific orcas have been extensively researched, orcas further south, termed the Eastern Tropical Pacific (ETP) group, have received relatively little study. The ETP group refers to orcas ranging from the south of the Baja California Peninsula to northern Peru, and also includes offshore orcas near Hawaii. The ETP group may constitute a distinct ecotype or otherwise be morphologically unique. Morin et al. (2010) included four ETP groups in their phylogeographic analysis of orcas: one from Clipperton Island, one from Mexico, and two from Hawaii. The Mexico and Clipperton Islands orcas clustered with the offshore ecotype. One Hawaii group clustered with the transient ecotype while another was more closely related to the Eastern North Atlantic population.

ETP orcas do not appear to have unique subpopulations; rather, they are distributed widely over their range. For example, an individual first identified in Mexico was photographed approximately 5,535 km away in Pucusana, Peru. From 2001 to 2017, another individual was identified in Mexico, Costa Rica, Ecuador, and Peru. The orca was possibly moving in time with humpback whale breeding season and was observed attacking a humpback calf during one encounter. ETP orcas are also known to feed on marine mammals, sea turtles, elasmobranchs, and bony fish.

Falkland Islands
Falkland Islands orcas have been referred to as an ecotype. However, Yates et al. (2007) stated that the Falkland whales match the description of the Type A form. Currently, they have not been designated a particular ecotype. Falkland Islands orcas have primarily been studied at Sea Lion Island (SLI), where southern elephant seals (Mirounga leonina) and South American sea lions (Otaria flavescens) breed. Whales remain further offshore until mid-November, when elephant seal pups first begin entering the water. Orcas use at least two different predation techniques: hunting in shallow water and ambush-style attacks at rock platforms. Falkland orcas have occasionally been observed preying on sea lions and penguins as well. Falkland Islands whales form pods composed of mother-calf pairs, and these pods may associate with one another, especially during predation events. Researchers use a transient-resident dichotomy to describe individuals: "transients" have been observed at SLI for a few days at most, while "residents" are routinely seen. These two types also associate with one another. After predation events, orcas have been observed facilitating the feeding of calves, sharing prey, and socializing.

Currently, the Falkgland Islands orcas' year-round range and their food source outside the pupping season is unknown. Additionally, orcas have been observed offshore in the northeast Falkland Islands Interim Conservation and Management Zone, approximately 200,000 km from the Islands. Few sightings during at-sea surveys and a very low stranding record suggest an overall low abundance around the Falklands.

Japan
A mammal-eating population inhabits waters off of Hokkaido, Japan. Though the study of these whales is relatively new, they have been characterized as transients based on prey type and genetic evidence. However, Japanese orcas display behavioral differences in hunting style and migratory patterns compared to PNW transients. Further research is needed to determine if the PNW ecotype model should be applied to Japanese orcas.

Japan's orcas undertake migrations, seemingly related to sea ice presence in Nemuro Strait. Satellite-tagged whales from Kushiro and Rausu migrated to Kuril Islands, and some further northwest. The Kushiro and Rausu populations may be largely independent, as orcas displayed differences in vocalizations and migration ranges, and few individuals were commonly sighted in both regions. A phylogenetic analysis found that, in addition to the transient population, an offshore- or resident-like population may also exist in Japanese waters.

South Africa
In mainland South Africa, orcas have been categorized as the Type A ecotype. Orcas have been observed preying on dolphins, whales, sharks, fish, squid, and seabirds. Best et al. (2010) suggested that they may be opportunistic generalists due to these observations, as well as analysis of landed whales' stomach contents. Previously, Williams et al. (2009) described South African orcas as offshore fish-eaters based on depredation events at longline fisheries.

However, multiple morphotypes or ecotypes may inhabit the region, evidenced by three stranded animals. These whales, which displayed very worn teeth, were termed flat-toothed forms. Adult length was approximately 1 to 1.5 meters shorter than whales taken at whaling stations, but their flippers and dorsal fins were relatively larger. The stomach contents of one whale was entirely fish, including blue shark (Prionace glauca) remains. The flat-toothed form is seemingly rare in coastal waters and may instead reside mostly offshore. Engelbrecht et al. (2019) documented two events where orcas preyed on sharks in False Bay with a specialized feeding tactic. Orcas were previously only known to depredate marine mammals in False Bay. They posit that a different group or ecotype, such as the flat-toothed form, may have visited the area.

https://www.researchgate.net/profile/Simon-Elwen/publication/361638937_Fear_at_the_top_killer_whale_predation_drives_white_shark_absence_at_South_Africa's_largest_aggregation_site/links/62d4f7aba6abd57c6aeea4ed/Fear-at-the-top-killer-whale-predation-drives-white-shark-absence-at-South-Africas-largest-aggregation-site.pdf

Other regions
The ecotype status of many orca populations has been discussed, but largely hampered by a paucity of ecological, genetic, and morphological data. No ecotypes have been recognized in the western North Atlantic or Canadian Arctic.

https://cdnsciencepub.com/doi/pdf/10.1139/cjz-2019-0207

Additional ecotypes may inhabit the waters of the Fiji and Papua New Guinea. Orca sightings in Fiji are uncommon. Photographed Fiji whales were darkly pigmented, to the extent where their saddle patches were not visible. In Papua New Guinea, orcas feed on elasmobranchs and bony fish. Two individuals have been noted to have grey under-flukes, rather than the typical white coloration.