by Anders Reimer
The weekend is here (finally!) and you decide to treat yourself to a little fresh air and scenery. Of course, the best way to escape the LA fog is to go for a local hike in the Santa Monica Mountains. Mile after mile of wonderful hiking trails meander to and fro across the hills until at last they lead to the coolest location, the stream. On a hot day, a walk near the water can feel like a cold hand over a fevered brow. You decide to stop and take break for a while. The babbling water seems to beckon you to take a dip but you realize that to hike back to your car a few miles while soaking wet is not enjoyable. You compromise with the persistent water and decide to put your feet in instead. The week’s stress wash away with the chilly but satisfying water. Your worries about dentist appointments, business meetings, fights with love ones, all wash away with the healing stream water. As you slip into blissful relaxation you feel what seems to be chop sticks dance across your toes. Startled a bit, you look down to observe what looks like a miniature lobster walking across your feet. You quickly remove yourself from the water but not before one clamps down on your toe with its large claw. YEEEEOOOWWW!! This is your first experience with an introduced species of crustacean called a crayfish.
It shouldn’t be surprising that the red swamp crayfish (crawfish, crawdad, craw daddy, craw-fish-bug, whatever) is such an incredibly resilient species. Its hard shell, quick movement, and sharp claws keeps the most voracious predators at bay while terrorizing native species that have it tough enough as it is. These native species have to deal with native predators and the incredibly taxing drought here in Southern California. The drought makes it difficult for amphibians and fish to live as many of the prime breeding and spawning locations are now covered in thick layers of mud or worse… completely dried up altogether. It would be nice if we could help our ectothermic (cold-blooded) friends by making their lives just a little easier. That is where Mountains Restoration Trust (MRT) comes in with its Crayfish Removal Program.
Between three and four days a week we trap and remove crayfish from our backyard, the Santa Monica Mountains. Specifically, we are trapping in places within Calabasas city limits. These include Malibu Creek State Park and De Anza Park, among others. You, the reader, may have even taken part in one of our many community outreach programs where we gather volunteers to rid our streams of this terrifying menace. For that, MRT and the animals of the stream say a big THANK YOU!
I don’t want to wave my hands in the air saying “the sky is falling!” and that crayfish are the embodiment of Lucifer ,but they are certainly not good news. We know little about amphibians, but what we do know is that they are very fragile. They are being wiped out at an alarming rate. Some speculate that as many as 1/3 of the world’s 6,800 species of amphibians are in danger of going extinct. This is due to a number of factors including pollution, habitat degradation, disease, and introduced predators.
So what do crayfish do exactly that makes them so detrimental to the local stream ecosystem? I’m glad you asked, well informed reader. The thing about crayfish is that they can attack all three of the major life stages of amphibians. It starts with the eggs of the amphibians. Amphibians lay eggs in groups called masses. An egg mass may contain a hundred eggs in space no bigger than a golf ball. Now without proper defenses these egg masses are just a quick meal for a hungry crayfish and will gobble them up. If there are no more eggs, there are no more of the next stage of an amphibian’s life, tadpoles. Tadpoles are relatively slow swimmers when you compare them to a crayfish so they are an easy target. If the crayfish are unable to be satisfied after having their fill of eggs and tadpoles then they will move on to their next meal, adult frogs and newts. If the frogs have developed this far from eggs and tadpoles then they are considered the lucky ones. Their other brothers and sisters are the quick meal of the crayfish. They are not in the clear though, as they may be the third course in the crayfish meal. Usually they are quick enough to escape the crayfish by hopping or walking on dry land but every once and a while you may come across a frog amputee which fought but lives to see another day. You may also see a California newt with a couple bites taken out of it by some oblivious crayfish. I say oblivious crayfish, because they are unaware that California newts produce a potent neurotoxin that will kill any animal that tries to eat it. So now there are nibbled newts out in the Santa Monica Mountains streams and an equal amount of dead crayfish that didn’t think before they bit.
So how did these crayfish get here? Our best guess is that these crayfish were brought here in the early 20th century by fishermen. These fishermen would use crayfish to catch another non-native species, largemouth bass, in the local rivers and lakes. Either they stocked the lakes on purpose or threw whatever bait they didn’t use back into the stream but in any case they stuck around. They don’t take long to adapt and grow exponentially in an environment. Each female can carry a hundred babies at a time and reproduce multiple times a year. Since then, they had roughly 100 years to proliferate and make the lives of native aquatic critters much more difficult by predation and competition for limited resources.
Our history with the crayfish program is relatively short. We started in the late summer/ early fall of 2011. Back then it was a hodgepodge of volunteers from all different environmental organizations around Southern California. As it grew, we saw the necessity of having a healthy stream not just for the sake of the plants and animals of the streams, but for our own well-being. When I was younger, I remember going out into my backyard and catching western toads. I spent hours waiting past dusk when the lumpy toads would emerge and start their calls, “whoop whoop whooop.” There wouldn’t be a day I didn’t hear or see them. Most of the time they were too quick for me or had such a good camouflage that I would never see them even though they may be calling just a few feet away. As I grew older, I heard them less and less. I knew it wasn’t the case as in the polar express where you’d lose the ability to hear them as you were older. I knew that there were indeed less toads than there were in the past. Maybe it was my love of animals that caused me to miss those calls but If I could I would make sure that those lumpy toads would still be around in my backyard and my neighborhood. You may be saying “why is this guy talking about his lonely childhood catching ugly creatures in his backyard,” but bear with me. The point is, you don’t miss something until it is no longer around. Many of you grew up in Ventura or northern Los Angeles County and know what the characteristic call of a pacific tree frog or California tree frog sounds like. The way things are going in the world including the damage caused by crayfish, those may be the last time you hear their call.
Anders Reimer is with the Mountain Restoration Trust, a non-profit land trust dedicated to preserving natural land in the Santa Monica Mountains through restoration, education and land acquisition headquartered in Calabasas.