Posts Tagged: fish
A recent study led by UC Cooperative Extension specialist Van Butsic used high resolution satellite imagery to conduct a systematic survey of cannabis production and to explore its potential ecological consequences.
Published this spring in Environmental Research Letters, the study focused on the “emerald-triangle” in northern California's Humboldt, Mendocino, and Trinity counties, which many believe is the top cannabis-producing region in the United States.
The UC Berkeley-based Butsic and his co-author Jacob Brenner used Google Earth imagery to locate and map grow sites (both greenhouses and outdoor plots) in 60 watersheds. Most cannabis grow sites are very small, and have gone undetected when researchers used automated remote sensing techniques, which are commonly used to detect larger changes such as deforestation.
“We chose to use fine-grained imagery available in Google Earth and to systematically digitize grows by hand, identifying individual plants. Most plants stand out as neat, clear, little circles,” said Brenner, who is on the faculty of the Department of Environmental Studies and Science at Ithaca College. “The method was laborious — it took over 700 hours — but it proved to be highly accurate.”
Butsic and Brenner paired their image analysis with data on the spatial characteristics of the sites (slope, distance to rivers, distance to roads) and information on steelhead trout and Chinook salmon, both of which are listed as threatened species under the federal Endangered Species Act. These and other species are vulnerable to the low water flows, soil erosion, and chemical contamination that can result from nearby agriculture.
Results of the study show 4,428 grow sites, most of which were located on steep slopes far from developed roads. Because these sites will potentially use significant amounts of water and are near the habitat for threatened species, Butsic and Brenner conclude that there is a high risk of negative ecological consequences.
“The overall footprint of the grows is actually quite small [~2 square kiliometers], and the water use is only equivalent to about 100 acres of almonds,” says Butsic, who is in the Department of Environmental Science, Policy, and Management at Berkeley. According to Butsic, California currently has more than one million irrigated acres of almonds.
He stresses that the issue lies in the placement of the sites: “Close to streams, far from roads, and on steep slopes — cannabis may be a case of the right plant being in the wrong place.”
Last year, California legislature passed laws designed to regulate medical marijuana production, and state voters will weigh in on whether to legalize recreational marijuana this coming fall. Given these changes as well as the profitability of cannabis production, Butsic expects that marijuana cultivation will expand into other sites with suitable growing conditions throughout the region. He and Brenner assert that ecological monitoring of these hotspots should be a top priority.
Bills recently signed into law by Governor Jerry Brown have made some advances in this direction — requiring municipalities to develop land use ordinances for cannabis production, forcing growers to obtain permits for water diversions, and requiring a system to track cannabis from when it is first planted until it reaches consumers.
But the researchers say that regulation will likely be a constant challenge because it will rely on monitoring procedures that are just now emerging, as well as voluntary registration from producers and budget allocation from the state for oversight and enforcement.
“Some of the same fundamental challenges that face researchers face regulators as well, primarily that cannabis agriculture remains a semi-clandestine activity,” says Brenner. “It has a legacy of lurking in the shadows. We just don't know — and can't know — where every grow exists or whether every grower is complying with new regulations.”
At least 13 of the 102 aquarium species that are imported into California have been introduced into California marine waters, according to a recent report by Susan Williams, professor in the Department of Evolution and Ecology at UC Davis and a marine ecologist the Bodega Marine Laboratory. These introduced species have a high success rate (69 percent) in establishing themselves.
Two very invasive species — the predatory lionfish and Caulerpa seaweed (aka “killer algae”) — have reportedly come from the aquarium trade. The lionfish, which has established itself along the East Coast where it eats smaller fish and threatens reef ecological systems, has not yet reached California waters, but the Caulerpa seaweed cost California more than $6 million to eradicate from two Southern California lagoons a decade ago.
At least 34 aquarium species were found to be potential invaders in California marine waters.
“Globally, the aquarium trade has contributed a third of the world’s worst aquatic and invasive species,” Williams said. "Lionfish are voracious predators in their native habitats, and in their invaded habitat any predator is a potential threat to the native ecosystem."
Williams’ advice: "To avoid releasing aquarium species into natural water, don’t dump your aquarium where they can become an expensive and harmful pests.”
She said that people should contact the vendor where the fish was purchased or the California Department of Fish and Wildlife to learn how to dispose of aquarium species responsibly.
- Complete UC Davis news release, by Kat Kerlin
- Our AmazingPlanet report
- Environmental News Network report
- Science on NBC News report
The competition between farmers and fish for precious water in California is intensifying in wine country, say biologists at the University of California, Berkeley.
The researchers found that juvenile steelhead trout are particularly at risk during the dry summer season typical of California’s Mediterranean climate. Of the juvenile steelhead trout present in June, on average only 30 percent survived to the late summer. In years with higher rainfall and in watersheds with less vineyard land use, the survival of juvenile trout over the summer was significantly higher.
The researchers pointed out that salmon and trout conservation efforts have not adequately addressed summer stream flow. Previous studies have highlighted other limiting factors such as habitat degradation and water quality, while this study documented the importance of water quantity for restoring threatened populations.
Grantham says he is not suggesting we get rid of vineyards. “But we do need to focus our attention on water management strategies that reduce summer water use. I believe we can protect flows for fish and still have our glass of wine.”
Long before European settlers arrived in America, the Los Angeles River was an important source of food and water for native peoples. Europeans settled the Los Angeles area in part because of the river and the fertile alluvial soils it provided. The river and its tributaries frequently flooded and changed course, forming wide alluvial floodplains that extended across southern Los Angeles from modern day Santa Monica to Long Beach. When Los Angeles began its transition to teeming metropolis and settled these flat floodplains, the river's natural characteristics led to disastrous flooding.
In the interest of saving lives and property, civil engineers sloped the banks and encased them in more than 30 miles of concrete, a move that completely altered the fishery. Recently completed UC Cooperative Extension research indicates that, despite the concrete and influx of pollutants from LA storm drains and sewage treatment plants, the Los Angeles River is still capable of sustaining life.
Working with Friends of the Los Angeles River, an organization interested in restoring the LA River to a more natural state, UCCE natural resources advisor Sabrina Drill surveyed the fish population in the river's eight-mile Glendale Narrows area, a section that, because of its underlying geology, was left with a natural bottom. The researchers discovered a diverse and bountiful fish population in this stretch of the river.
"To our surprise and delight, toxicity reports show the small number of fish we tested to be free of mercury and have extremely low levels of PCBs," Drill said. "This may not be true for the rest of the river. Glendale Narrows is one of the cleanest sections, probably because the natural river bottom cleans itself and because of the high quality effluent coming out of upstream water reclamation plants."
The survey identified eight species of fishes, none of them native, plus tadpoles and red swamp crayfish in the river. The eight fish species are: fathead minnow, carp, black bullhead, Amazon sailfin catfish, mosquito fish, green sunfish, largemouth bass and tilapia. They hail from Africa, South America, Eastern North America and Asia.
Whether reestablishment of native species to the river is possible remains to be seen, and may not be the most important factor in river restoration.
"Difficult though it may be, you can't make the LA River what it used to be simply by digging up the concrete," Drill said. "Because of all the development, the water we import, and changes in hydrology, temperature, and water quality, it’s not the same system it was before people settled here."
But restoration can still take place, and Drill believes that in the next 10 to 20 years, large-scale habitat restoration and restoration of some historical floodplains will dramatically enhance the ecological function and natural beauty of the Los Angeles River.
LA River Fishing
USC film maker Megan McCarty created a seven-minute documentary on fishing the Los Angeles River, which includes an interview with UCCE's Sabrina Drill. See the video here:
Click the link below for the complete 21-page report on the Los Angeles River fish survey.
The Los Angeles River winds through urban metropolis.