Sea otters, the fuzzy mascots of the California coast, have fought back over the past 75 years from near-extinction. From the 1970s to the 1990s, their numbers steadily grew. But recently, their population growth has stalled. Scientists aren’t sure why, but they are alarmed. One key suspect: house cats.

In a study published in 2002, UC-Santa Cruz researchers reported that 62 percent of 107 dead sea otters collected along the California coastline from Half Moon Bay to Santa Barbara were infected with Toxoplasma gondii, a parasite found in cat waste. Biologists say they think otters are being exposed to the parasites from yards and litter boxes — whether the waste is flushed indoors or washed from outdoor areas into storm drains and streams.

Although they haven’t made a definitive connection – toxic chemicals in boat paint, blooms of harmful red tides and other theories also abound; scientists and environmental groups convinced Sacramento lawmakers in 2006 to pass a bill offering new protections to otters while the research continues. Signed by Gov. Arnold Schwarzenegger in September, the measure requires all cat litter sold in California starting Jan. 1, 2007 to have a warning label telling people not to flush it down the toilet. The bill also creates a new check-off box for donations on state tax forms to fund more sea otter research into parasites and diseases, and it doubles penalties for harming otters to $25,000. Quest follows the researchers, and sits in on an otter autopsy as scientists try to unlock the mystery.

Discuss the "What’s Killing the Sea Otters" TV segment 15 March,2016Amy Miller
  • wayne

    I hate to sound sarcastic but why do you come off
    as always wanting to blame.I think we’d be better
    served by educating the people not to dispose of their kitty liter thru toilets’ much the same way
    we used to throw our oil down the sewers in the
    50s & 60s not realising exactly where it went its
    pretty obvious these days now that sewers are
    marked warning people that they drain into the bay.Much of the same kind of effort could be spent on saving the otter people are generally
    concerned once their educated.

  • Richard Blons

    Unfortunately it’s via a combination of blame (which I found less scolding and persistent than you seem to see) and experimentation that we’re able to practice the scientific method in a world where the variables are so numerous as to be impossible to accurately ascertain.

    If there is no blame, little (perhaps incorrectly targeted) legislation, and little action (but much discussion) on further education efforts we’ll never see the effects of these changes in time. People need to be blamed, people need to be educated, and people need to be forced, all in tandem, to do more about this problem.

    Frankly, people need to stop thinking, and start taking direct and tangible action on these issues. We need to accept legislation such as has been proposed, and if it doesn’t work we need to accept the next step of legislation if we want something positive to happen here.

  • Laura

    Regarding the whole flushing cat litter down the toilet problem…Is it the litter or the cat feces the problem?
    The program said the parasite was found in cat feces. There are currently several lines of cat litter that claim they’re biodegradable and flushable because they don’t contain clay and other chemicals. Assuming Quest reported the problem correctly (that it’s more a feces, not litter ingredients issue- can anyone reaffirm this?), it’s good to know what is in the litter is only part of the problem, since any flushing seems to be harmful for the sea otter.

  • Charles

    Doesn’t cat litter that is flushed get routed to the sewer treatment system? Does the bacteria make it through that system?

  • elizabeth

    toxoplasmosis parasites would be larger than bacteria yet our sewer treatment plants can trap and filter out bacteria but not parasites? and why has PUC and other water treatment plants not informed the public about this?

  • Margaret

    Laura’s question was a good one. I had heard not to flush kitty litter, but I didn’t know that was the actual feces that was the problem. That needs to be said a little more clearly. It isn’t the litter – it is the cat feces that is the problem. Obviously they usually go hand in hand, but not always.

    And who cares about blame! Let’s just do something about it.

  • Tim

    Great topic, and interesting show, but Quest does really need to clarify the cat feces disposal problem, and to recommend a solution. I thought I was doing good by flushing LuLu’s business down the toilet clumped in wheat-based, sustainable swheat scoop. I was surprised Quest didn’t recommend an alternative method besides flushing. Should we dispose of the waste in the weekly garbage collection? Should we bury it in the yard? Tell me soon because more is certainly on the way!

  • Paul Rogers

    Hi Laura and Charles,

    To answer your question, the toxoplasma gondii parasite is found in cat feces. That means that used cat litter is problematic to flush down the toilet. Although scientists still have many unanswered questions, they do know that one way the parasite could be getting into the ocean is through people flushing used cat litter down the toilet, because although sewage treatment plants can remove many contaminants in sewage, they are unfortunately not able at this piont to remove this kind of hardy microscopic parasite. Sewage treatment plants along the coast release their treated wastewater into the ocean through outfall pipes that can be a mile or more long.
    Although there are other contaminants which may be harming otters, including pesticides and other chemicals, environmental groups working on otter issues were sponsors and supporters of the bill that Assemblymen Dave Jones and John Laird wrote last year which requires all cat litter sold in California starting this spring to have a warning label telling people not to flush it down the toilet. Governor Schwarzenegger signed that bill into law last fall.
    An alternative way to dispose of used cat litter is to put it in a plastic bag, tie off the top, and put it in the garbage.
    Thanks for watching QUEST and for taking the time to write! We think you’ll like our show going forward.

    Paul Rogers
    Managing Editor

  • Laura

    Hi again and thanks to everyone who posted re the cat litter question.
    I did a basic search on toxoplasma gondii online and found some interesting facts, at least I’m hoping the website’s credible and they’re facts (here’s the link:
    The link talks about how cats get infected w/toxoplasma by eating infected prey or raw meat and bones. The site also states that infected cats only pass the parasite in their feces for a few weeks after being infected. ATHOUGH, the reproductive form (oocysts) can “survive several years in the environment and are resistant to most disinfectants.” So even assuming that most cats aren’t actively passing the parasite in feces, seems that a small percent that are infected can endanger otters for years if the parasite is living in the water! : (
    Paul suggested throwing away cat litter by putting it in plastic bags and then the garbage, but that doesn’t seem like the greatest option either. Plastic bags take years and years to decompose and once the parasite reaches the landfill, then what? It’d probably harm something else, maybe even otters indirectly if a landfill is near a water source linked to their environment.
    The peteducation site also says toxoplasma gondii can infect people, so maybe we’re more the problem than the cat litter…Reasons to buy environmentally safe kitty litter, from not wanting carcinogens in the home to clay litter swelling to over 15x its size once flushed, can be found here:

  • This segment is especially important at a time when sea otter researchers, conservation groups, and others are not entirely sure what is killing sea otters in California and how exactly to turn this trend in a positive direction.

    Along these lines, California passed legislation in September 2006 that would better protect the federally threatened California, or southern, sea otter from illegal killings, water pollution, disease, and other impacts. The bill, among it’s main objectives, calls for fines of up to $25,000 for illegal killings, establishes a research program, through a tax check-off, to address pollution and other mortality issues, and changes labels on cat litter packaging to encourage pet owners to throw used cat litter into the garbage instead of flushing it down the toilet. Research has shown that many sea otters have been infected with a deadly pathogen, Toxoplasma gondii, which is found in cat feces.

    The tax check-off, CA Sea Otter Fund, “would require money in that fund, upon appropriation by the Legislature, to be allocated to the Department of Fish and Game for the purposes of establishing a sea otter fund, as prescribed, and to the California Coastal Conservancy for research and programs related to improving the near-shore ocean ecosystem, including, but not limited to, program activities to reduce sea otter mortality.” The portion of the tax check-off that goes to the Department of Fish and Game would be use for “investigation, prevention, and enforcement actions to decrease sea otter mortality.”

    The Franchise Tax Board requires that, in the first year, the CA Sea Otter Fund raise $250,000 in order for this check-off to remain on the income tax 540 form in subsequent years.

    For more information on the sea otter tax check-off, please visit

  • Gearal Marantz

    In talking to the many environmentalist who supported this bill, I found it very funny that none of them want to live near a landfill. Prof. Conrad said it would smell. Support a law that asks people to throw their cats waste into a landfill but none want to live near one…LMAO!

    California spends billions of your tax dollars building and maintaining waste treatment facilities. They exist to “process” animal waste, rather than have it sit untreated in landfills. The process may not clean the waste 100%, but at least it is treated, so that it less toxic to ALL living creatures.

    Lets throw untreated waste with all its parasites and other unhealthy contagions into landfills, were it will sit for years, decades…crazy!

    The most environmentally responsible way of disposing your pets waste will always be to flush it and the new law does NOT make that illegal. Even if it did, call me a criminal I will continue to flush my cats waste.

    How many people died from spinach contaminated from untreated waste coming in contact with it? Are all landfills safe from runoff? Lets fill them up with untreated waste…brilliant!

    To solve the problem and the parasite is the problem not the cat feces.

    1. Research how to kill the parasite at waste treatment level.

    2. Pass a law forcing everyone to throw their pets waste down the toilet.

  • Pingback: What’s killing sea otters? | Six-String Gypsy()

  • Dr. John Lap

    Gearal Marantz got it right and the rest (including the program) focused on the one thing that will not solve the problem and in essence got it wrong.

    1. Over 93% of all cat litter is clumping and you CANNOT flush it down the drain. The research group in the program also tested the outflow of the sewage treatment plant by hanging mussels and found NO TOXO.
    2. Cats can only get toxo and pass eggs in their feces for the most part ONCE in a lifetime. Feral cats are EVERYWHERE in the Morro Bay area and breed like crazy
    3. The Feral cats and outdoor cats are most susceptible to toxo and, also, poop outside (guess where it goes after a rain…into storm drains and into the bay).
    4. Most cats (especially rescued kittens from feral colonies) have already had toxo and by the time many are adopted have passed their toxo eggs (oocycsts) and will most likely NEVER pass them again.

    With all due respect Mr. Rogers the method recommended by you and UC Davis is wrong the part of the law about flushing is wrong and irresponsible. Here is why:

    1. Indoor cats using a cat box are almost no risk. The odds of them passing oocycsts are slim to none. They either have done so already or if being fed regular cat food will not get infected.
    2. If they get toxo when you put the litter, in the landfill, in your bag guess what happens at landfills. Huge tractors with studded steel wheels drive over it and break open the bags (this is done on purpose). Well what is in landfills? Feral Cats and rodents, the perfect team to continue the process.
    3. As I said, clay litter is 93% of the litter used and that is not good for a landfill is strip-mined and can cause many other problems in landfills that get that toxo back into the environment.
    4. Finally, the real problem for otters is not and would not be flushing. It is Feral Cats, Wild Cats, chemicals and dirty storm drains. The leaders in toxo research will tell you point blank, the otters will have to adapt because there is no way to get rid of toxo.

  • Gerald Marantz

    Mr. Rogers

    Why no response to Dr. Lap and my comments?

    Thank You

    G. Marantz

    “Cats excrete the pathogen in their feces for a number of weeks after contracting the disease, generally by eating an infected rodent. Even then, cat feces are not generally contagious for the first day or two after excretion, after which the cyst ‘ripens’ and becomes potentially pathogenic. Studies have shown that only about 2% of cats are shedding oocysts at any one time, and that oocyst shedding does not recur even after repeated exposure to the parasite. Although the pathogen has been detected on the fur of cats, it has not been found in an infectious form, and direct infection from handling cats is generally believed to be very rare.”

    So, indoor-kept cats who have no rodent contact are not going to be shedding oocytes and their owners can happily keep flushing. I know I will be – I’d much prefer that to adding plastic to landfills!

    (And this is one more reason to keep your cats indoors, safe, and not harming wildlife or being harmed by it.)

  • marie

    this parasite, is the SAME parasite, that can cause birth defects / complications in pregnant women, and why pregnant women are instructed by their OB/GYN NOT to handle litterbox waste. This is nothing new. Anyone who’s ever been pregnant, and had cats has heard of this parasite.

    As for this parasite being the cause of otter population decimation, I would think it would be more logical / probable, that if it were something coming from the sewage treatment, it would be from the chemicals / cleaning products that people flush down their drains. Since most of those things can be filtered out at water treatment facilities, it would follow, that so would toxoplasma gondii.

    Cats have been around for abotu as long as otters i’m sure, and have this organism in their excrement almost as long. Otters have come into contact with it in the past too I would imagine.

    If my waste can be treated and deemed ‘safe’, my cat’s going into the treatment facility can be as well.

    If the otter population is not growing as well as previously, maybe it has more to do with warming ocean waters, food supply problems, or contaminated food supply. Otters eat a lot of clams and such, and these creatures need fairly cold waters in which to thrive.

    Nothing like California to jump the gun and not have all the facts. I’m glad that there is concern for the health of wildlife, but come on folks, let’s think a bit logically here, so we can find the REAL culprit.

    While I flush my kitty litter, it’s made from corn and not clay. Never flush clay based litters, as they will solidify in water, and become glue=like and potetially cause major plumbing issus.

  • G. Marantz

    Still waiting for a responce to our issues.

  • D. Topper

    The U.S. Environmental Protection Agency recommends one of the best ways to dispose of pet waste is to flush it down the toilet, to prevent potential contamination of human drinking water:

    A quote from the bulletin, above:
    “The most effective way for pet owners to limit their pet’s contribution to source water
    contamination is to simply clean up and dispose of pet waste. As long as the droppings are not
    mixed with other materials, pet waste should be flushed down the toilet. This allows waste to
    be properly treated by a community sewage plant or septic system … ”

    Also, a subsequent study of the sea otter toxo problem found the problem was not concentrated at areas where urban sewage plant runoffs entered the ocean, but in areas where storm water runoff, streams, etc., entered the ocean. There are more feral cats in the the U.S. than domestic ones (some estimates say 78 million compared to 73 million). None of them are using the toilet. They’re also far more likely to be infected with toxo since they catch and eat live game. (In fact, some naturalists estimate as many as 60 per cent of all wild animals have, or have had, toxo.)

    Certainly no one wants to see sea otters disappear. But blaming house cats for their problems seems a bit of oversimplification. There’s a heck of a lot of crap in the oceans, all of it our fault. Hopefully research will continue.

    But at this point, keeping your cat indoors and using the toilet would seem to be the best bet for the environment. As well as giving small wildlife and birds — especially birds, which are under siege by domestic cats across the continent — a much-needed break, it also means you’re not adding to the local landfill and your cat is prevented from eating the raw game that’s the source of Toxo in the first place. (And then leaving droppings outdoors that will definitely enter the watershed, and be completely untreated when they do so.)

    As for the water used to flush the toilet, why do so? It’s a pretty tiny bit of urine, after all. I think it can wait! (That’s got nothing to do with the cat, anyway; I believe that very few actually flush.)

  • David A. Jessup

    Cat poop and Toxo are one of a number of pollutants that are impacting southern sea otter health, the health of marine ecosystems and human health. The Jones-Laird Bill recognizes non-point source pollution “including but not limited to Toxoplasma gondii..” as contributing to the sea otters problems. See “Sea otters in a dirty ocean” by Jessup, Miller et al, Journal of the American Veterinary Medical Association, December 15, 2007 for the most comprehensive article written address the breadth of the problem in plain american english (not sciencese).

  • renee

    Well, I’d say that warnings not withstanding, the word isn’t going out… I went to the link on the reply from Laura,, & it’s obvious that the people blogging at this site have no idea they shouldn’t be flushing cat waste… and this was YOUR link… did she read their blogs? Check it out…

  • Pingback: Cat litter: An environmentalist’s dilemma | green LA girl()

  • G. Marantz

    Still waiting, or don’t you respond to arguments that refute your “facts”?

  • Chris Bauer

    Drop in California Sea Otter numbers

    According to a report put out today by the USGS, the California sea otter population is in decline for the second year in a row. Sea otters are a federally listed threatened species.

    Tim Tinker of the USGS Western Ecological Research Center and lead scientist for the annual survey notes, “We have seen a decrease in sea otter numbers throughout most of their range, particularly in those areas where most of their reproduction occurs.” “A number of human and natural factors may be influencing this trend, and we are working to better understand what those are.”

    The data suggests increased mortality, particularly in breeding-age females as a main factor. Otters are dying in higher than usual numbers from multiple causes, including infectious disease, toxin-exposure, heart failure and malnutrition.

    Since sea otters live in the near-shore coastal waters, they are directly exposed to pollutants running off land and into the ocean. “Remember, sea otter health can tell us a lot about the health of the coastal waters that humans also enjoy,” Tinker says. “So, we’re eager to learn more.”

    If you want to learn more, see:

    And to see additional graphs, maps and data summaries of the survey results go to:

  • G. Marantz

    Still waiting

  • G. Marantz

    Still waiting.

    Hope you research your other reports better than this one. This law did absolutely nothing to protect Sea Otters. It did put money into the organizations that sponsered the legis. Now isn’t that nice.

    Yep the cat feces are perfectly safe in those solid plastic bags. Birds, rats etc. won’t be able to get in those solid plastic bags. Better yet, those big machines compacting and running over those unbreakable plastic bags will protect the sea otters from the nasty parasite in the feces in those unbreakable solid plastic bags.

    Makes good TV though with cute sea otters.

  • Anonymous

    Cat waste should NOT be flushed down the septic system because the waste water system cannot destroy the transmitting agent and it survives the Waste Water Treatment, until ingested, whereupon it can bloom. According to the internet, it can survive Chlorox bleach, and pasteurization. It needs temperatures of water of 160 degrees F or 67 degrees C to kill it. A dryer can kill it. Aids patients with toxoplasmosis are also using the septic system. One can get it from undercooked lamb and from undercooked pork or from contaminated vegetables etc. They suggest washing hands and more washing hands. People wokring in restaurants need to wash their hands.

  • Anonymous

    I think if I were a sea otter I would choose to move, (sarc). You realize that humans dump hospital sewage, slaughterhouse blood, funeral home human fluids, residential stuff from people undergoing chemotherapy, from people with Aids with Toxoplasmosis, people with communicable diseases, all sorts of drugs that people take. The sewage treatment facilities say they can handle most of it. However it turns out that the prions of Creutzeldt- Jakob, aka the human form of Bovine Spongiform aka BSE, aka Mad Cow Disease such as in the blood of patients who have died go straight to the sewer, and waste treatment cannot touch prions. It makes me glad that I don’t go into the coastal waters. I know that surfers can get Staph infections, and MRSA. and that beach sand also has many potential pathogens.Surfers are recommended to stay out of the surf if they have open sores or fresh tattoos. An article says that drying things with heat for clothes is healthier than air dried fabrics.Beachapedia on Staph Infections recommends one drink coffee and tea:”Coffee and Tea Drinkers May Be Less Susceptible to MRSA”. Maybe we should be introducing sea otters to coffee breaks and tea time (sarc) (^_^). Then there are possible allergies to perfumes, detergents, etc. I am very grateful to my immune system, and it makes me happy that I keep kosher and don’t eat shellfish.
    Fortunately Santa Cruz CA tests the water at beaches and creeks and lagoons and posts when water quality is not safe such as with e-coli.

  • G. Marantz

    Still waiting after all these years. Oh, well…time to go flush.


Amy Miller


Amy Miller is a documentary filmmaker and the Supervising Producer and Partner at Spine Films, a boutique production company specializing in science, natural history and art content.  Prior to joining the Spine team, she worked at KQED as the Series Producer of “QUEST”, a multimedia science and environment series. She was also a staff producer for two other KQED series, “SPARK” and “Independent View.” For her work in television, she’s earned multiple honors including ten Emmy awards and two AAAS Kavli Science Journalism awards.  Feature Producer/ Director credits include “Saving Otter 501” for PBS NATURE and “Let All the Stories Be Told” which aired as part of KQED’s “Truly California” series.

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