Get to Know a Species: Invasives
In Malibu Creek, you’re more likely to see a non-native carp or catfish instead of a native Arroyo chub or goby. While these species might not make a difference in enjoying your outdoor experience, it’s a huge difference for the ecosystem. Carp and catfish, along with bluegill, largemouth bass and even abandoned goldfish are just some of the many invasive species in the Malibu Creek watershed.
Frank Vargas Jr. holding a carp he caught in Malibu Creek. Photo courtesy Debbie Sharpton
These aggressive species thrive because they crowd out indigenous species, eat anything, and have few predators. “They create an imbalance in the ecosystem”, explains Debbie Sharpton, conservation vice president of Fly Fishers International, Southwest Council. She has battled crayfish in the creek since 2010. Crayfish produce rampantly and eat native fish eggs. She’s also witnessed the change in the creek’s native fish populations, “When I first started removing crayfish, Arroyo chub would get in our traps, and we’d release them back into creek, but now we don’t get any at all.”
Black Bullhead are in the catfish family and popular for stocking upstream ponds and lakes. Photo courtesy Debbie Sharpton
Where did the non-natives come from? One source are the upstream communities with constructed ponds and lakes. Many of these water bodies contain bass, sunfish, carp, and other non-native species. During the rainy season, the ponds often flood, flushing water into Malibu Creek and bringing the invasive fish along. Also, over the years, people have used the creek for aquaculture and have dumped live bait into the stream and tracked in mud snails. Bull frogs have also been introduced, preying upon and out competing native frogs and other aquatic and terrestrial species.
The catch and keep Fishing for Conservation program helps remove aggressive nonnatives so southern steelhead will have a better chance for survival in local waters. Photo courtesy of Bernard Yin.
High populations of invasive species are considered harmful enough to be on par with other pollutants like mercury and lead. Under the Clean Water Act, Malibu Creek is listed as polluted with non-native species by state and federal environmental protection agencies. This designation can help acquire funding to reduce populations and restore water quality.
With the growing numbers of invasive fish, Sharpton created a new program, “Fishing for Conservation: Steelhead Recovery in Malibu Creek.” Anglers can get maps, information and parking passes to “catch and keep” non-native fish. The program also helps with collecting data from both organized group and single anglers that can be passed on to scientists working in the watershed. For information about the program, visit MCSP.
The Santa Monica Mountains is one of the largest and most significant examples of a Mediterranean-type ecosystem which is only found in 2.3 percent of the world’s land area. Native fish and amphibian populations are an essential part of the region’s tremendous biodiversity. They are a critical part of the food web and serve as a key indicator to the overall health of the ecosystem. A system that includes humans too.
Courtesy of Hashi Clark