Exotic animals deployed as Delta ‘weed whackers’


Coast guard crews keep close watch on the pod of hippos grazing in and around the weed-infested Stockton Deep Water Ship Channel. Photo courtesy of U.S. Coast Guard

By Nestle J. Frobish

Visitors to the Sacramento-San Joaquin Delta are doing double takes lately as they encounter some newly introduced “biological controls” to keep a fast-spreading waterweed from damaging boat propellers and choking off waterways.

Working with state water officials, UC Davis scientists last month released a herd or “bloat” of hippopotamuses from Botswana to chow down on vast mats of water hyacinth that also threaten to clog the intake to the California Aqueduct near Stockton.


Water hyacinth in Delta. 

Elsewhere in the Delta, the researchers also planted hyacinth-loving manatees imported from Florida and giant guinea pig-like rodents from Brazil called capybaras.

The menagerie of radio-tagged herbivores is part of a yearlong experiment in more natural and, some say, more effective, controls for curbing the menacing growth of non-native aquatic weeds in the Delta.

Source: Wikicommons

A hippopotamus pokes its head out of the hyacinth-covered Clifton Forebay in the Delta. Source

Enlisting hippos in the biowarfare is the brainchild of Robert Broussard, a professor with the UC Davis Center for Watershed Sciences who has long touted biological controls as a cost-effective way to keep the growth of hyacinth in check.

“What better way to fight an alien species than by introducing still more alien species?” Broussard said.

State and local agencies have poured millions of dollars into chemically and mechanically clearing Delta waterways of the hyacinth, a floating ornamental plant, and the submerged Brazilian Waterweed. But this year the combination of severe drought and slower-flowing, nutrient-laden water has created a perfect storm for waterweed growth. There is no known way to eradicate the weeds.

Source: California Department of Water Resources

In 2014, the state treated 2,617 acres of water hyacinth in the Delta with the herbicides glyphosate and 2,4-D. Source: California Department of Water Resources

In some areas the invasive plants have grown so dense that they have threatened not only boat safety and the Delta’s ecological balance but also cargo ship traffic and the state’s water supply.

“Hippos were the furthest things from our minds when we asked UC Davis to find alternative solutions,” said Terry Drinkwater, spokesman for the California Department of Water Resources. “But, I must admit, when it comes to water hyacinth, these river horses are as hungry as, well, horses.”

In their native African habitat, hippos mainly eat aquatic plants, including hyacinth, which they devour at a rate of 200 to 300 pounds a day. The mammal’s affinity for the plant inspired the character “Hyacinth Hippo,” the prima ballerina from the “Dance of the Hours” sequence of Disney’s Fantasia. 


Brazilian waterweed. Photo: California State Parks

“We believe the rate of consumption will be even higher in the Delta with Brazilian waterweed spicing up the mix,” said Broussard, adding that he routinely blends the weed into his own diet of mainly Cajun cuisine.

Officials are taking special measures to keep onlookers at bay because hippos are highly territorial and would likely attack people who encroach on their turf.


Students of UC Davis professor Peter Moyle (background) pose with a manatee last week before releasing the mammal into Delta waters. Photo by Bo Manfree/UC Davis

The Coast Guard has volunteered a crew to shepherd the bloat of hippos currently grazing in the Clifton Court Forebay, a reservoir that serves as the intake for California Aqueduct diversions to Southern California. Working from jet skis, the crew has been herding the hippos between the forebay and the Stockton Deep Water Ship Channel, where boating and shipping has been stymied by floating mats of hyacinth.

Coast Guard Lieutenant Commander Quinton McHale called the effort in the Delta a “war on weed” and said the public safety interest is no different from law enforcement’s effort to combat marijuana growing along California’s north coast.

“You might as well call the Delta the ‘Emerald Triangle,’” McHale said in a recent interview aboard his patrol board, PT-73.

Stockton Mayor Anthony Silva said he plans to promote the hippos as another tourist attraction for the destination city.

UC Davis water science student coax a capybara into the waters at the Delta Yacht Club of the San Joaquin River. The marina is infested with water hyacinth. The rodent is known to devour up to 40 pounds of the invasive weed a day. Photo by Bo Manfree/UC Davis

“I’m just trying to think of everything,” Silva said. “You just know darn well there’s got to be a way we can make money off those big bad boys. Hippos in Stockton is a wacky idea, so we’re calling them ‘Weed Whackers’. Get it?”

Researchers will be comparing the hippos with the more gentle manatees and the web-footed capybaras on feasibility, cost and effectiveness in the waterweed control experiment.

Follow-up work will include a special genetic breeding program to create more voracious aquatic herbivores. “If this doesn’t work, we will be considering barriers in the Delta to limit the spread of waterweeds,” said Cornelius Biemond, deputy director of water supply at the Department of Water Resources.

Jake Lunge, director of the Center for Watershed Sciences, said that adding these “four-legged locusts” to the state’s arsenal of pesticide spraying boats and mechanical waterweed harvesters will likely boost the state’s water supply during this fourth year of severe drought.

“Grazing these vast mats of hyacinth will reduce evapotranspiration and save a lot of water,” said Lunge, a civil professor of ornamental engineering.

“This could help keep California from running out of water by the end of the year.”

Nestle J. Frobish, former chairman of the Worldwide Fair Play for Frogs Committee, is curator of the UC Davis Center for Watershed Sciences.

VIDEO: MSNBC’s Rachel Maddow Show picks up California WaterBlog story on Delta hippos

Further reading

Andersen, T. “Water hyacinth thrives in drought-stricken Delta.” Bay Nature. Dec. 22, 2014

Breitler, A. “Stockton mayor floats an idea: Bring in manatees.” The Record (Stockton). Nov. 8, 2014

Breitler, A. “Port of Stockton: Vessel stopped by tangled mats of hyacinth,” The Record (Stockton)Oct. 28, 2014

Fitzgerald, M. “Hyacinth? Think giant amphibious hamsters.” The Record (Stockton). Nov. 3, 2013

Hippopotamus Stew. Cooks.com

Jackson, W.T. and Paterson, A.M. (1977), “The Sacramento-San Joaquin Delta – The evolution and implementation of water policy – an historical perspective.” Contribution No. 163. California Water Resources Center, UC Davis

Miller, G. “The crazy, ingenious plan to bring hippopotamus ranching to America.” Wired. Dec. 20, 2013

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41 Responses to Exotic animals deployed as Delta ‘weed whackers’

  1. Careful with this approach. Each animal you bring in is a new factor in the local ecology, as is all of its digestive flora and other parasites. What thrives in its new environment is likely to become invasive.

  2. Paul says:

    Good one Dr. Lund, you got me! I started making plans to take my daughter to Stockton this weekend.

  3. Edith MS Robbins, PE says:

    What about introduction of exotic bacteria/parasites/snails from hippo fecal matter into the local water bodies?

  4. Pingback: Daily Digest: Water uncertainties remain for many growers, stunning photos of Lake Tahoe, and should water wasters face jail?, plus exotic animals deployed in Delta, Save Our Concrete protestors, and more news, real and not …MAVEN'S NOTEBOOK |

  5. Trina Wood says:

    Nice to see the April 1st edition continued!

  6. Pingback: Daily Digest: Water uncertainties remain for many growers, stunning photos of Lake Tahoe, and should water wasters face jail?, plus exotic animals deployed in Delta, Save Our Concrete protestors, and more news, real and not …MAVEN'S NOTEBOOK |

  7. Steve Macaulay says:

    Good to see Nestle J. Frobish articles every year. The photography this year almost looks like Photoshop was employed, but I would doubt that from our trusted academic institutions. Looking forward to the next Frobish article — perhaps something along the lines of Fair Play for Hippos?

  8. Don Strong says:

    UC Davis introduces crocodiles to Sacramento Delta to control hippos.

  9. Teresa F. says:

    After the crocodiles are introduced to the Sacramento Delta to control hippos, we will start allowing harvesting of the crocodiles for food and hide to pay for the program. The new UC food research center in Sacramento will feature locally harvested grilled croc kabobs (for crocodiles are surely more tasty than hippos) with a side of hyacinth salad.

  10. Good one! Had me believing until I saw the reference to Lt. Cmdr. Quinton McHale

  11. April Fool’s. Our water is too cold and hippos are freaking dangerous…lol.

  12. Pingback: Hippos and Capybaras | doctor keely

  13. Pingback: Exotic animals deployed as Delta ‘weed whackers’ | doctor keely

  14. Dawn Gulick says:

    I just watched it on #Maddow. Well done, well done!

  15. Nancy says:

    Quinton McHale, Pt-73 and Cornelius Biomond….yep, almost had me LOL I remember when they were going to ‘drain’ the Sacramento River to clean all the debrie out. Happy April 1st everyone ^_^

  16. johannadesilentio says:

    OK, I know this is a joke story, but the water hyacinth problem is real! An entrepreneur in Mexico whose city was facing the same problem turned these clogging plants into a resource, creating an super absorbent material used to clean up industrial (oil, chemicals, etc.) spills . Two birds with one stone! His patent :http://www.google.com/patents/WO2007120031A1?cl=en Get an entrepreneur on the case and Incentivize eco-friendly removal!

  17. Isn’t plural for hippopotamus “hippopotami”?

  18. Ian Random says:

    Finally, California does something intelligent.

  19. Deb says:

    Sheep would have been a better option. they’re indigenous to the US. This isn’t a great idea. Anytime we introduce a new species to an area that don’t naturally inhabit – we create problems. We need to learn to follow natures lead.

  20. Pete Xander says:

    The quote by UC Davis’s Robert Broussard, “What better way to fight an alien species than by introducing still more alien species?” is the epitome of environmentally contemptuous 19th Century stupidity. Do the hippos eat only the water hyacinth? Or do they also eat Spartina and Salicornia, two wetland obligate species that are vital for healthy habitats of endangered species?

    Were the Capybaras neutered/spayed, or is northern California going to be overrun by two-foot-long, 35-pound rats? Ask anyone in Bayou Country what they think about Nutria. Ask any fisheries biologist what he/she thinks about state wildlife agencies in the past who were dumping rainbow trout into every stream and lake imaginable, breeding rare subspecies of cutthroat and redband trout, like California’s spectacular freshwater State Fish, the golden trout, out of existence or on critically endangered species lists? How many visitors to the lakes and creeks in the Sierra Nevada are happy with fishing for introduced brook trout, which quickly fill lakes with stunted, scrawny 6″ fish that fight as hard as a wet cotton ball? How deep is DFG’s (now known as the DFW . . . apparently because “Game” implies the fact that you can’t “catch-and-release” a deer when Bambi’s brains have been blown out by a cartridge from a thirty-ought-six) research on these introductions? Haven’t we learned ANY lessons from the past?

    Hippos are also notoriously unpredictable and violent, going from zero to rampaging two-ton assholes in fractions of a second. Will Broussard be held personally liable if a crazy hippo goes ballistic on people photographing them from small boats, smashing the boat and killing the occupants? Do we know if any of these introduced exotics carry any diseases, insects, nematodes, or other unwanted bugs in their systems?

    They might be efficient lawn mowers, but the flippant attitude Broussard demonstrated shows that he is the kind of shallow-thinking, money first, common sense later person who typifies the environmental disasters unleashed when a seemingly good idea goes horribly, terribly wrong. I just hope the Port of Stockton has one shitpotfull of money or some multibillion-dollar liability insurance policies to cover their poorly researched and potentially reckless activities.

    • Dan says:

      You really should have read the other comments before you posted your tirade! This story was published on April 1st… 🙂

      There are definitely no hippos roaming the Delta, but there is a whole lotta Hyacinth – YUCK!

  21. gymnosperm says:

    Interesting way to smoke out the possessed. Maybe that’s what April first is all about…personally, totally in favor of the Manatees. They’re just way more chill.

  22. turn off the left hemisphere says:

    The photo is the most obvious Photoshop job I’ve seen in years! Reading these comments is cracking me up! Lmfao!!!

  23. just get some floating goats

  24. Pingback: Hippos to the Rescue | Parkway Blog

  25. quicksilver1953 says:

    We need more hippos! But only if they’re wearing tutu’s.

  26. Pingback: April 1st headlines in California #cawater #drought | Water Librarian's Blog

  27. Elany Prusa says:

    In Lake Chapala Mexico they really did import Manatees to help unclog areas of this huge lake outside of Guadalajara…..The manatees however died…even though the temperatures were similar to Florida conditions….and this is written on April 4th….google it!

  28. Bill Bates says:

    Hey Pete Xander. The Hippos are attacking people at the marina

  29. Bill Easton says:

    Why don’t they mechanically remove the WH and compost it for AG?

  30. Pingback: This Was No April Fool’s Joke – greenbirdingmendo

  31. Chris Rossiter says:

    How feasible would it be to harvest the WH for livestock feed or compost? This could be done either mechanically or use minimum security inmates on work details.

  32. Lila says:

    I knew it was a hoax when they were claiming the hippos were at the port of Stockton and the photo was of Pittsburg where they do not have a hyacinth problem

  33. Marcus Pun says:

    Nice joke, but we do have American zoo bred hippos, so that might mitigate the exotic intestinal flora and fauna. Still, I don’t think anyone has ever managed a herd of hippos in the past million years. So probably a good reason not to use them.

  34. J R says:

    Would be great if residential homes could do this sort of thing as well. Unfortunately we would be fined for having exotic and/or farm animals.

  35. Pingback: Flashback Friday: Supersharks - FISHBIO Fisheries Research, Monitoring, and Conservation

  36. Joseph G says:

    Awesome photo! LOL

  37. zidane says:

    thank you for the article

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