Pesticide Investigations at WIL

Pesticide Investigations at WIL

Pesticide Investigations

In 2009, over 156 million pounds of pesticide active ingredients were used in California. This pesticide use has come with some cost to fish and wildlife resources of the State. CDFW formed the Pesticide Investigations Unit in 1964 to address ongoing effects of fish and wildlife from pesticide use. This unit later became part of the Wildlife Investigations Laboratory (WIL).

For More Information, please contact:
Jaime Rudd, PhD

The WIL continues to protect fish and wildlife from adverse pesticide impacts by investigation of pesticide-related incidents, involvement in the pesticide registration process, participation in monitoring studies, and education of pesticide users on impacts to fish and wildlife.

Fish and Wildlife Loss Investigations

Fish loss

Each year, WIL investigates reports of fish and wildlife losses due to pesticide use. If it is determined that the loss was caused by pesticide exposure, coordination with the appropriate County Agricultural Commissioner's Office will help ascertain whether the pesticide was used according to the label or was an illegal use. In the case of an illegal use, enforcement action may be taken by CDFW and the County Agricultural Commissioner's Office. If the use was according to the label, it is important for WIL to monitor the situation to determine the extent of the problem and if regulation change is needed to protect wildlife. A current example of this is the legal use of anticoagulant rodenticides causing non-target exposure in predators and scavengers.


Pesticide Registration

Pesticide Application

In California, pesticides are registered for use by the Department of Pesticide Regulation. As part of the California registration process, data regarding the efficacy and safety of pesticides is reviewed by the Pesticide Registration and Evaluation Committee (PREC) which can recommend restrictions to reduce or eliminate potential problems. As the custodian of fish and wildlife in California, CDFW serves on the PREC. This allows CDFW to review new pesticide uses and to request reevaluation of existing pesticide uses when unacceptable hazards to fish and wildlife have been demonstrated.


Solving Pesticide Problems in California

Hawk Study

Over the last four decades, CDFW has been involved in many monitoring studies of pesticides in the environment. These studies typically are designed with the objective of describing and solving a pesticide exposure problem. One example of this is monitoring rice pesticides in the Sacramento River which led to losses of tens of thousands of fish in the 1980s. In the 1990s, CDFW and UC Davis investigated the loss of raptors in orchards caused by the use of organophosphate insecticide dormant sprays. In the 1990s, CDFW monitored the effectiveness of legislation restricting the use of tributyltin antifouling paints in San Diego and Lake Tahoe. CDFW has also completed assessments of hazards posed by a number of pesticides to aquatic organisms in California.


Current Challenge: Anticoagulant Rodenticides in Wildlife

Kit fox

WIL is currently monitoring anticoagulant rodenticide exposure of predatory and scavenging wildlife. The majority of predators and scavengers tested have been exposed to anticoagulant rodenticides. Please refer to the links for more information and to find out how you can help protect wildlife.

Education to Prevent Pesticide / Wildlife Incidents


In California, those holding licenses or certificates to handle, sell, or recommend pesticides are required to complete hours of continuing education classes. WIL personnel give presentations at these classes describing causes of pesticide-related wildlife exposure and preventative actions. In this way, licensed pesticide users are kept informed of the latest information available and are able to use pesticides more safely.