Science Spotlight

The fall 2020 issue of California Fish and Wildlife (PDF), CDFW’s quarterly scientific journal, features a series of scientific articles on the environmental impacts associated with legal and unpermitted commercial cannabis cultivation. Once primarily hidden deep in the forests of the Emerald Triangle, cannabis cultivation activities are now occurring all over California.

Like other forms of commercial agriculture, land use practices associated with cannabis agriculture can pose a serious risk to many threatened and endangered species. Elijah Portugal and Jason Hwan, CDFW scientists, explore the environmental impacts with an article titled “Applied Science to Inform Management Efforts for Cannabis Cultivation, Humboldt County, California” (PDF). The piece focuses on the preliminary findings of a study examining the impacts of cannabis cultivation on private lands in and near remote, forested watersheds of northwestern California. This area has supported decades of illegal cultivation and today, includes both legal and illegal cannabis grows in the same watershed.

The State Water Resources Control Board’s Cannabis Cultivation Program reviews observations from the field in a part of the state that has not been historically reported on with a piece titled “Two Years After Legalization: Implementing the Cannabis Cultivation Policy in Southern Coastal California” (PDF). Some of the initial findings indicate that ninety four percent of the 519 enrollees in the Cannabis General Order are discharging their industrial wastewater to publicly owned treatment plants, while the remaining enrollees haul their industrial wastewater to a permitted wastewater treatment facility. Along with this, the unit has also supported state and county enforcement efforts and inspected numerous illegal cultivation sites and observed activities that could be detrimental to water quality and numerous fish and wildlife species.

Researchers from the University of California, Berkeley and CDFW present a piece titled “Coexisting with Cannabis: Wildlife Response to Marijuana Cultivation in the Klamath-Siskiyou Ecoregion" (PDF), which examines local wildlife community dynamics on and nearby active private-land cannabis farms. Using camera data collected between 2018–2019, scientists monitored numerous wildlife species within the Klamath-Siskiyou Ecoregion in southern Oregon. The results suggest that cannabis farms were generally occupied by smaller-bodied wildlife species, and had a higher proportion of domestic dogs, cats and human activity as compared to nearby comparison sites. They conclude that wildlife will likely have species-specific responses to cannabis cultivation and suggest the need for educational resources on wildlife-friendly growing practices.

Learn more about other cannabis research studies in this issue and what scientists are learning, including reviews of the potential impacts of pesticides, artificial light, noise pollution and trash.

For over 100 years, the California Fish and Wildlife scientific journal continues to publish high-quality, peer-reviewed science that contributes to the understanding and conservation of California’s wildlife. We look forward to the contributions of the next installment.

Media Contact:
Janice Mackey, CDFW Communications, (916) 207-7891

CDFW scientists rescuing juvenile Coho Salmon from isolated and drying pool habitats in Olds Creek, a tributary to the Noyo River in Mendocino County.


CDFW crew relocating steelhead and Coho Salmon to a lower pool on East Weaver Creek in Trinity County in June of 2015.


In July 2016, this usually perennial pool on Matilija Creek in the Ventura River watershed went dry, killing several juvenile steelhead.

One silver lining to emerge from the severe drought that impacted California earlier this decade was that it whetted an appetite to study the event and compile data designed to help fish and aquatic species better weather future droughts.

The state experienced one of the warmest, driest periods in recorded history during this five-year drought (2012 to 2016).

In Jan. 2014, then-Governor Jerry Brown declared the drought a state of emergency. His proclamation directed all state agencies to act to prepare for and mitigate drought-related effects on water supply and aquatic species. The California Department of Fish and Wildlife (CDFW) responded by enacting “drought stressor monitoring” on a statewide level, and recently released a summary report on that effort entitled Statewide Drought Response: Stressor Monitoring (PDF).

In late 2016 to early 2017, drought conditions improved considerably in most of the state when winter storms delivered higher than average levels of rainfall. The report describes the results from a collaborative statewide monitoring effort carried out during the period of 2014 to 2017 by scientists from CDFW and other agencies.

The primary purpose was to collect information on the status of populations of fish and other aquatic species, their habitats, and the water quality in the streams in which they reside. The intent was to provide both the scientific community and the public with a better understanding of potential drought-related threats to vulnerable species, and measures taken by CDFW and other agencies to alleviate these threats. This information was also necessary to help CDFW make better-informed management decisions.

The knowledge and data gained in this effort will be used to guide both CDFW and other resource managers during future droughts.

“This was a monumental statewide monitoring effort in response to drought impacts,” said CDFW Environmental Program Manager Jonathan Nelson. “The Drought Stressor Monitoring” developed important baseline documentation of the environmental changes associated with the severe drought conditions, and how the changes affected aquatic habitats and fish populations throughout the state. It was vital to collect this baseline, so we would better understand how to respond both in the present and in the future by creating a boiler plate. This document summarizes the monitoring framework implemented from 2014 to early 2017, how these data informed management actions, and how these efforts will hopefully minimize the impacts on fish and aquatic species during future droughts.”

Overall, CDFW monitored habitat conditions for 17 aquatic species in 141 watersheds, spanning 28 counties. Key findings from the monitor efforts identified several patterns of drought-related ecosystem change throughout the state including 1) increased loss of stream connectivity; 2) degraded water quality, including reduced levels of oxygen and elevated water temperatures; 3) high elevation streams impacted by the formation of winter anchor ice; and 4) elevated instances of fish being stranded by low streamflow and adversely affected by poor water quality.

Drought stressor monitoring was integral to management actions and was particularly critical to the process of aquatic species rescue. Fish rescues were only undertaken after Drought Stressor Monitoring information showed that populations were at high risk of becoming locally extinct in the immediate future. CDFW scientists developed special criteria and guidelines to assess the threat of drought and when to initiate rescue operations. When suitable habitat was available, fish were relocated to nearby habitat within the same stream or watershed to ensure the genetic health of the population and to maintain local adaptations. In cases where habitat was not available, fish were relocated to nearby hatcheries for temporary holding.

Approximately $3 million was dedicated to this effort from then-Governor Brown and more than approximately 100 CDFW staff members contributed to the monitoring and report-summary efforts. CDFW’s Fisheries Branch spearheaded the compiling of the data and finalized the report in collaboration with staff in the department’s various regions.

View the final report (PDF).

CDFW Photos.

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Media Contact:
Kirsten Macintyre, OCEO Communications, (916) 322-8988
 

Surveying Ventura River in Ventura County


Snorkel survey in Hollow Tree Creek in Mendocino County


Hollow Tree Creek steelhead

Taking care of California’s fish and wildlife wouldn’t be possible without managing the resources upon which they depend. To that end, CDFW has an entire branch – and many scientific staff – dedicated to the scientific study, and planning and management of water resources.

Within the Water Branch, CDFW’s Instream Flow Program (IFP) is tasked with collecting and contributing data necessary to make all kinds of important management decisions about ecological function, fish rearing, spawning and migration and habitat suitability.

In the simplest terms, “instream flow” refers to the rate of the water running through a waterway in a natural environment. But when one considers all the interests competing for use of that water – fisherman, boaters, farmers, businesses, water districts, and fish and wildlife themselves – the complexity of the subject is evident.

Measured in cubic feet per second (cfs), instream flow can be measured at different times of the year in a specific location in a waterway. The fluctuations can tell scientists quite a bit about the ecosystem health of a watershed. While some watersheds have flowing water throughout the year and others are intermittent it is often the responsibility of water managers to distribute the water between uses. CDFW, a natural resource management agency, is faced with the complex task of identifying and recommending instream flows necessary for supporting natural resources. Determining instream flows are crucial so that aquatic, riparian, and terrestrial resources dependent on water will be considered and protected during water distribution activities.

Guided by the California Water Action Plan, the Public Resources Code and the Fish and Game Code, IFP staff conduct flow studies, collect field data, develop guidelines for quality assurance, conduct outreach and coordinate with other agencies and interested parties on program-related activities.

In the past year, some of IFP staff’s largest projects have included:

• A flow study at the South Fork of the Eel Watershed, which supports threatened coho, Chinook and steelhead.
• A study of 46 coastal steelhead streams (Ventura County to Siskiyou County) to develop flow criteria and evaluate historic flow trends.
• A flow study to identify flow regimes that will protect endangered Southern California steelhead in the Ventura River.
• Technical studies and final flow recommendations based upon the needs of South-Central Coast steelhead in Monterey County’s Big Sur River.
• Ongoing training for IFP staff, to ensure that field studies in swift water are carried out safely.

To learn more about these specific projects, please download the IFP’s 2017 Year in Review (PDF) document, available on CDFW’s website.

A Featured Scientist Q&A with the IFP manager Robert Holmes is also available on the CDFW Science Institute page.

CDFW photos. Top photo: IFP staff hold a planning meeting prior to a survey on the Ventura River in Ventura County