Delta Invasive Species

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Invasive Animal Species in the Delta

The Sacramento-San Joaquin Delta is one of the world’s most invaded estuaries, with at least 185 non-native species already here and more likely to arrive in the future.

Below is information on some of the invasive species currently in the Delta and Suisun Marsh, species to watch out for, how to report invasive species, and additional resources.

Species of Concern

Invasive species of concern currently in the Delta and Suisun Marsh.

Animals

An American bullfrog in a person's hand. Image by Kerwin Russell, Riverside-Corona Resource Conservation District.

American bullfrog

Lithobates catesbeianus

Photo by Kerwin Russell, Riverside-Corona Resource Conservation District

A gray wild cat on the run leaping and looking intensely forward. Adobe stock image.

Feral cat

Felis catus

Photo by alan1951/Adobe Stock

A dark-colored feral pig in a field. Image by California Department of Fish and Game.

Feral pig

Sus scrofa

Photo by CDFW

Close-up of a single golden clam. Image by Noel M. Burkhead, U.S. Geological Survey.

Golden clam

Corbicula fluminea

Photo by USGS

Close-up of a cluster of golden mussels being held in a gloved hand. Image by California Department of Water Resources.

Golden mussel

Limnoperna fortunei

Photo by DWR

Many tan-colored New Zealand mudsnails (Potamopyrgus antipodarum) shown with a dime for size reference. Photo by U.S. Geological Survey.

New Zealand mudsnail

Potamopyrgus antipodarum

Photo by USGS

Image of a nutria's head, showing its white whiskers and orange teeth. Image by California Department of Fish and Wildlife.

Nutria

Myocastor coypus

Photo by CDFW

A red-eared slider stretched out on a rock with a waterway in the background. Image by California Department of Fish and Wildlife.

Red-eared slider

Trachemys scripta elegans

Photo by CDFW

A red swamp crayfish on a rock. Image by U.S. Geological Survey.

Red swamp crayfish

Procambarus clarkii

Photo by USGS

Plants

The white flower and green leaves of an alligatorweed (Alternathera philoxeroides) plant. Photo by National Plant Data Center, Baton Rouge, LA.

Alligatorweed

Alternathera philoxeroides

Photo by National Plant Data Center, Baton Rouge, LA

A section of the Brazilian egeria (Egeria densa) plant. Photo by Lara Gudmundsdottir.

Brazilian egeria

Egeria densa

Photo by Lara Gudmundsdottir

Brown, fluffy seedheads and green leaves of the nonnative common reed (Phragmites australis subsp. australis) plant. Photo by Erlend Bjortvedt.

Common reed

Phragmites australis subsp. australis

Photo by Erlend Bjortvedt

Curlyleaf pondweed (Potamogeton crispis) plants in the water. Photo by Christian Fischer.

Curlyleaf pondweed

Potamogeton crispus

Photo by Christian Fischer

Eurasian watermilfoil (Myriophyllum spicatum) in the water. Photo by Fungus Guy.

Eurasian watermilfoil

Myriophyllum spicatum

Photo by Fungus Guy

Giant reed (Arundo donax) plants growing in the Sacramento-San Joaquin Delta.

Giant reed

Arundo donax

Purple loosestrife (Lythrum salicaria) plants with purple flowers and green leaves. Photo by Liz West.

Purple loosestrife

Lythrum salicaria

Photo by Liz West

White flowers and green leaves of the perennial pepperweed (Lepidium latifolium) plant. Photo by Leslie J. Mehrhoff, University of Connecticut, Bugwood.org.

Perennial pepperweed

Lepidium latifolium

Photo by Leslie J. Mehrhoff, University of Connecticut, Bugwood.org

Ribbon weed (Vallisneria australis). Photo by Nick Rasmussen, California Department of Water Resources.

Ribbon weed

Vallisneria australis

Photo by Nick Rasmussen, DWR

Purple water hyacinth (Eichhornia crassipes) flowers with yellow and blue markings and green leaves growing in the water. Photo by Wouter Hagens.

Water hyacinth

Eichhornia crassipes

Photo by Wouter Hagens

The flower and leaves of a water primrose plant (Ludwigia spp.). Photo by Bouba.

Water primrose

Ludwigia  spp.

Photo by Bouba

South American spongeplant (Limnobium laevigatum) in the water. Photo by Cardex.

South American spongeplant

Limnobium laevigatum

Photo by Cardex

Species Watch List

A northern watersnake (Nerodia sipedon) with brown and tan stripes in the grass next to a rock. Photo by Patrick Coin.

Northern watersnake

Nerodia sipedon

Photo by Patrick Coin

A southern watersnake (Nerodia fasciata) with tan, brown, and red-striped skin in the grass. Photo by CDFW.

Southern watersnake

Nerodia fasciata

Photo by CDFW

Five dark brown/tan-striped and five light brown/tan-striped Quagga Mussels (Dreissena rostriformis bugensis) shown next to a dime in a person's hand for size reference. Photo by CDFW.

Quagga mussel

Dreissena rostriformis bugensis

Photo by CDFW

Grouping of bright-green water lettuce (Pistia stratiotes). Photo Troy Evans, Great Smoky Mountains National Park, Bugwood.org.

Water lettuce

Pistia stratiotes

Photo Troy Evans, Great Smoky Mountains National Park, Bugwood.org

A single yellow floating-heart (Nymphoides peltata) surrounded by green vegetation. Photo by Lyn Gettys, University of Florida, Institute of Food and Agricultural Sciences.

Yellow floating-heart

Nymphoides peltata

Photo by Lyn Gettys, University of Florida, Institute of Food and Agricultural Sciences

A Zebra mussel (Dreissena polymorpha) with brown, tan, and cream-colored stripes.

Zebra mussel

Dreissena polymorpha

 

Report Invasive Species

Report an Invasive Species Sighting to the California Department of Fish and Wildlife (CDFW)

Report a Pest to the California Department of Food and Agriculture (CDFA)

Resources

Information from CDFW

Information from the California State Parks Division of Boating and Waterways

Quick-Start Guide to Managing Invasive Aquatic Vegetation (IAV) in Tidal Wetland Habitats of the Sacramento-San Joaquin Delta and Suisun Marsh

Golden Mussels’ Threat to California Agriculture