Her mother, J16, has also declined in the past month, perhaps because of the burden of helping catch and share food with J50, experts said.
"The Center for Whale Research has had a vessel on the water looking for J50 for the past three days", the agency said. The West Coast Marine Mammal Stranding Network and airlines flying in and out of the San Juan Islands are on the lookout, he said.
Without J50, the population is now down to 74 members - their numbers reached almost 100 in 1995 - and many of its existing female members are nearing the age where they will no longer be able to reproduce, Ken Balcomb, founder and principal investigator of the Center for Whale Research, told The Washington Post in July.
The Center for Whale Research in Friday Harbor, Washington said the last known sighting of J50 was September 7.
He said J50 has not been seen despite several days of favourable sighting conditions.
Her loss brings the population of orcas that spend much of their time in the Pacific Northwest to just 74.
David Ellifrit/Center for Whale Research via AP J35, also known as Tahlequah, pushed her dead calf around the Pacific Northwest for more than two weeks in what was widely seen as a mourning ritual.
"Not only are the Southern Resident killer whales dying and unable to reproduce sufficiently, but also their scarce presence in the Salish Sea is an indication that adequate food is no longer available for them here, or along the coast".
A.M. Update: Prolonged rain will bring floods
Cooper said floodwaters were continuing to rise, and he urged evacuees to "stay put" until they received "the official all-clear". Hundreds of thousands of homes across North and SC are without power and tens of thousands of people are in emergency shelters.
She was known for her spectacular breaches, as many as 40 in a row, sometimes with her body in an arch. Her "peanut head" became more pronounced as the layers of fat disappeared from the base of her head.
J50 has surprised people before, going missing for days, then turning up within hours of announcements that she perhaps was gone for good.
The Department of Fisheries and Oceans in Canada and the National Oceanic and Atmospheric Administration in the US launched a massive cross-border search effort Thursday. A sharpshooting veterinarian fired an antibiotic-filled dart into her, crews dropped live salmon in front of her to try to get her to eat, and scientists even mulled capturing her so they could diagnose and treat her.
Anxious about her survival, the NOAA Fisheries and its partners announced Tuesday that plans are underway to possibly capture J50 in an effort to save her life. Debate swirled over whether the agency should act, or why it hadn't acted sooner, and the ethics of such extreme intervention. "What J50 needed, and what her family continues to need, is healthy and abundant chinook salmon, which these orcas depend upon for survival". "They were really sweet together", Giles said. Losing J50 would also mean losing her reproductive potential. But she later turned up and was seen with her family.
Officials said they would intervene and rescue the orca if she became stranded or separated from the rest of her tightly knit group of whales.
Public meetings held by NOAA to hear concerns and thoughts from the public about southern resident killer whale recovery are still on schedule for this weekend, including one at 7 p.m. Saturday in Friday Harbor at the high school and 1 p.m. Sunday at the Haggett Hall Cascade Room at the University of Washington in Seattle.
Western parts of the United Kingdom are expected to be the worst affected, but the Met Office warning covers the North East too. Bizarrely temperatures could surge to 27C as we approach October. "There will be a dry and sunny start for England and Wales".
The play-calling will be criticized, but the majority of plays were doomed from the start simply because the Seminoles' offensive. He was replaced by redshirt freshman Tommy DeVito , who threw for 177 yards and a touchdown.
Emergency declarations were in force in Georgia, South and North Carolina, Virginia, Maryland and the District of Columbia. If confirmed by the National Weather Service, that would break the state record for rainfall from a tropical cyclone.
Hunt explained that the BPS plastic is more stable, "but it induced similar effects on the process of making eggs and sperm". The study concludes that these "findings add to growing evidence of the biological risks posed by this class of chemicals".
In Jacksonville, a relentless band of heavy rain gutted buildings, drenched streets and left wildlife to battle the rising waters. This will cause devastating flooding across much of Onslow County with travel made impossible and many homes completely flooded.
Barzee was treated at the Utah State Hospital for about five years following her arrest, and testified in 2010 against Mitchell. She added that Barzee was always a little vulnerable and that Mitchell was manipulative. "I am a Christian", she said.
Microscopic traces of ancient starches extracted from the Raqefet Cave (left) are compared to starches replicated in the lab. The efforts put into producing the alcoholic beverage showed the importance of the drink in the Natufian culture, he noted.
Ronaldo Smashes 400-Club Goal Mark In Europe
In one of the most revolting scenes imaginable on a field of play, Costa leaned right in and gobbed into Di Francesco's mouth. Juventus , chasing an eighth successive Serie A title, have 12 points, three ahead of Napoli.
Injuries: Roethlisberger expected to play vs. KC
Cornerback Joe Haden (hamstring) and guard David DeCastro (hand), who were both doubtful, will not play for Pittsburgh. Roethlisberger returned to the practice field on Friday and was listed as a full participant.
Ruth Davidson: PM job would risk my mental health
A year later she was diagnosed with clinical depression but the medication gave her "desperate, dark, bad dreams". But the 39-year-old today told The Sunday Times : 'You have to want it and I don't want to be prime minister.
Canelo eyes trilogy with Golovkin
It's possible it was even closer than that, a testament to how evenly matched and well-prepared the two fighters were. Khan was impressed by the quality of the fight and lauded Canelo for his gameplan. "I think we controlled the fight".
North Carolina TV station evacuates due to rising waters
The city of 29,000 that's near the North Carolina coast is surrounded by two rivers on the east and south. "We all know that". Hours before the storm made landfall September 14, workers at New Bern's WCTI-TV NewsChannel 12 had to abandon their studio.
Kenyan Eliud Kipchoge smashes marathon world record in Berlin
Kenya's Eliud Kipchoge reacts after winning the Berlin Marathon setting a new world record on September 16, 2018 in Berlin . Amos Kipruto of Kenya was second in 2:06:23 with Kenya's Wilson Kipsang , the former world record holder, third in 2:06:48.
Zimbabwe's government criticized over cholera outbreak
Informal housing areas without running water have mushroomed and basic infrastructure has collapsed after years of neglect. Patients infected with cholera receive treatment in a polyclinic in Harare , Zimbabwe , on September 14, 2018.
Former President Obama campaigns for Cordray in Ohio
This is not normal what we're seeing, it is radical. "Because what's at stake goes beyond partisan politics", said Obama. Obama should help spur turnout, especially among black voters whose participation fell off in 2016, Beck said.
Hockney work tipped to bust auction record
A swimming pool painting by David Hockney could become the most valuable work of art by a living artist sold at auction. The upcoming sale, Rotter said, "will definitely be a record for David Hockney at auction".