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A group of killer whales, known as the L55s, was observed by researchers for the Center for Whale Research on Aug. 17, when nearly all of the Southern Residents came together near the southern end of Vancouver Island. Photo: CWR, taken under permits NMFS 27038/DFO SARA 388

A no-death census year for Puget Sound’s orcas, with observations about a recent shift to more female births

For the first time since Census Year 1993, no deaths were reported this year among the Southern Resident killer whales, which frequent Puget Sound, according to the official census report.

Two new births were reported among the whales, increasing the population from 73 to 75. I would also like to share some potentially hopeful information about what appears to be a shift in the male-to-female ratio at birth.

While worthy of note, the finding of no deaths may be more a coincidence of the census calendar than a suggestion that conditions are improving for the Southern Residents, according to Michael Weiss, science director for the Center for Whale Research, which maintains a count of the whales and produces the annual census report.

“It’s a good thing to not having any whales dying in a year’s time,” Michael said. “It’s something worthy of celebration when these small victories come.”

Still, death is never far away. There is reason to believe that a 22-year-old male in K pod, K34 named Cali, died a few weeks after the 2023 census window closed on July 1. The census period runs from July 1 of one year to July 1 of the next.

Observers with the Center for Whale Research last spotted Cali (pronounced Kah-lee) on July 7 near the entrance to the Strait of Juan de Fuca. Photos suggest that he was a little thin at the time. On Aug. 17 and on Sept. 17, Cali was the only K pod whale not spotted when the group made two visits to Haro Strait in the San Juan Islands. If Cali is not seen during the next encounter with K pod, then the probability that he is still alive will be small enough to presume that he has died, according to CWR protocols.

Cali, which means “heart” in the Salish language, is the youngest offspring of Skagit (K13), who died in 2017 at the age of 45. He has two sisters still living, Spock (K20) and Deadhead (K27). A brother Scoter (K25) died in 2019.

Both of the new calves, L126 and L127, were born into L pod, as I reported in Our Water Ways in August, after it appeared that all the whales had been sufficiently observed for the 2023 census.

L126, a male, is the first offspring of L119, an 11-year-old female named Joy. L127, a female, is the third offspring of L94, a 28-year-old female named Calypso.

Male versus female ratio

Through the years, I’ve heard many concerns about the excessive number of male births compared to female births among the Southern Residents. Females are especially important to the population, as the total number of births is determined in large part by the number of females and their individual reproductive rates.

In a notable turn of events, eight of the last 10 births have been females, if one includes a newborn that died in 2018 before she was given an alpha-numeric designation. That calf, born to Tahlequah (J35), received much news attention for the motherly devotion shown by Tahlequah, who carried her deceased calf for 17 days.   

From a calendar perspective and without J35’s calf, 11 males were born from 2010 through 2019, compared to seven females. (Another four died before their sex was determined.) Since the beginning of 2020, we’ve seen five female births compared to only two males. This turnaround has been welcomed by everyone hoping to see the population recover.

All things being equal, one would think that the ratio of males to females would be close to 50-50, like flipping a coin. Is it merely by chance that males outnumbered females for so long, and now the balance has gone the other way? We know it is possible to flip a coin and get five heads — or more — in a row. Since the beginning of the Southern Resident census count in 1976, about 56 percent of the newborn calves have been male, Michael said.

While this could be random chance, it is also possible that the birth rate is skewed by outside influences. Theories abound about how environmental conditions can influence the sex ratio of various species, from plankton to mammals. Without getting into this lively scientific debate, I would note that a shortage of food and toxic chemicals have been identified among factors that can affect sex ratios in some animals. In Southern Resident killer whales, both food and toxics have been discussed as factors that could be limiting the orca population. Both factors also involve hormones that regulate complex systems in the body.

In 2016, University of Washington researcher Sam Wasser used hormones in killer whale feces to show that about 65 percent of the pregnancies among the Southern Resident population were ending early in miscarriages (Encyclopedia of Puget Sound). Such a high miscarriage rate could be impairing recovery of the population. While food supply appears to play a role in the pregnancy failure, as revealed by stress hormones, a recent study shows that the Southern Residents have an unusually high rate of inbreeding, which can also lead to nonviability in some cases. (Encyclopedia of Puget Sound).

Thanks to research using unobtrusive drones (unmanned aircraft) at more than 100 feet above the whales, scientists have been able to identify pregnant females far earlier in their pregnancy than before this technology was available. The researchers, including John Durban and Holly Fearnbach of SR3, are able to monitor the females beginning just four or five months into their pregnancy, which lasts about 18 months. Eventually, if a young calf does not show up, then one can conclude that either a miscarriage or neonatal death has occurred. Several such pregnancy failures have been documented. (Check out “No child left behind,” Natural History magazine, and SR3 news).

With respect to this year’s census report, the Center for Whale Research noted that J36, known as Alki, looked “extremely pregnant” on July 1 but apparently lost her calf by the next sighting on Sept. 11. Her first calf, J52 known as Sonic, was born in March 2015 and went missing in September 2017.

These varying types of information could help refine population viability analyses, which usually include a calculated risk of extinction for a given population. The work involves making assumptions about the rates of births and deaths, the ratio of males to females and so on. Changing the assumptions based on new information could possibly change the outcomes (Knowledge Project).

Most PVAs for Southern Resident killer whales have shown a clear population decline into the future with eventual extinction — unless one pushes the assumptions away from the status quo, such as with improvements in the environment, birth rate or other factors, some of which are difficult to control.

Under ideal circumstances, if all the females started reproducing and were able to give birth to six calves in their lifetime instead five, that might be enough to increase the population over time, said Brad Hanson, marine mammal ecologist with NOAA’s Northwest Fisheries Science Center. Five calves per lifetime is actually pretty good for a Southern Resident female, at least in the recent past, yet it is not uncommon for females in the Northern Resident community of British Columbia to have six calves. An important challenge for researchers is to identify the conditions that allowed the Northern Resident population to flourish while Southern Residents barely hang on.

Reproductive failures

The problem of the moment is that among females of reproductive age in the Southern Resident community, quite a few are not reproducing anywhere near a normal rate. For example, L90, a 30-year-old female named Ballena, and K36, a 20-year-old female named Yoda, are both well into her reproductive years but have not produced any calves, at least as far as anyone has observed. The first birth is often assumed to be at age 15, although younger moms have been seen, such as this past census year when 11-year-old Joy (L119) became a mother.

Meanwhile, 33-year-old L83, known as Moonlight, has not had a documented calf since her first offspring, L110 or Midnight, was born in 2007. That’s 16 years without a known offspring.

L91, a 28-year-old female named Muncher, is the younger sister of Moonlight. Muncher has not had a calf since her son Magic (L122) was her first born eight years ago.

L103, a 20-year-old female named Lapis, had her first offspring Lausuli (L123), a male, in 2015. She has not had another documented calf over the past eight years.

Since some of the females have had at least one calf, that suggests that the potential may exist for these females to produce more offspring, said Michael Weiss. If the problem is a lack of food or other conditions needed to make Southern Residents healthy, then maybe people will be able to find solutions, Michael said.

“From my perspective, the situation is bleak, but there is hope,” he said. “When you look at the number of reproductive-aged females, it is similar to what we see in Northern Residents. Quite a few whales have had failed pregnancies, so we know they can get pregnant. We just need to get them what they need to get through.”

Environmental restoration is underway, Michael noted. The removal of dams on the Elwha River near Port Angeles (Encyclopedia of Puget Sound) appears to be increasing the number of Chinook salmon — the primary prey of the orcas. Benefits also could come from dam removal underway recently on the Klamath River along the California-Oregon border (Associated Press), he said. Certainly, more can be done.

For a time, it looked as if the sex ratio was shifting further toward males in the Southern Resident population, he said. That was a worrisome proposition, but things may be changing, as very young females now outnumber very young males, providing the potential for more births in the coming years.

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