Santa Ana River Native Fish Study Active
Native Fish Population and Habitat Study, Santa Ana River, California
The Santa Ana River, the largest river in southern California, flows through diverse landscapes, from the high desert to urban and suburban areas in Orange, Riverside, and San Bernardino Counties, stretching approximately 96 miles (154 kilometers) from its headwaters in the San Bernardino Mountains to its mouth at the Pacific Ocean near Huntington Beach. The river is home to the Santa Ana Sucker (Pantosteus santaanae), a species endemic to the basin, and the Arroyo Chub (Gila orcuttii), a native freshwater fish in southern California. To protect these species and other sensitive habitats, the region has implemented Habitat Conservation Plans (HCPs), which are long-term management and conservation strategies for specific areas of land with endangered or threatened species. Native fish, also known as indigenous fish, are species that naturally occur in a specific region or ecosystem and have adapted to the local environmental conditions over time.
Problem Description
The Santa Ana Sucker (Pantosteus santaanae) and Arroyo Chub (Gila orcuttii) are extant native freshwater fishes in southern California. There are numerous threats hypothesized responsible for the poor condition of both fishes in the Santa Ana River. Consequently, the Santa Ana Sucker (Pantosteus santaanae) and Arroyo Chub (Gila orcuttii) are part of the Upper Santa Ana Habitat Conservation Plan, which was developed as a comprehensive program to assist in the development of conservation activities to protect, enhance, and restore habitat for covered species in the watershed. Developing a Habitat Conservation Plan requires sufficient knowledge of the populations of interest to develop plans for their protection and management. The ability to monitor population abundance and habitat availability with some level of confidence is important when developing plans such as the HCP and making management decisions.
Study Questions & Objectives
Study Approach
A stratified random sampling design has been used since 2015 to estimate native fish abundances within the currently known occupied section of the Santa Ana River. Sampling has included the use of backpack electrofishing, seining, and snorkeling methods. Recent surveys have focused sampling efforts on backpack electrofishing methods because they were estimated to be the most efficient at capturing native fishes in the river. As many as 68 random sampling reaches of 50 meters in length have been collected within a sampling year. All reaches have been sampled for fishes and habitat, which has been used to estimate the abundance of native and non-native fishes within the river, and determine how habitat characteristics affect the distribution of these fishes. This native fish abundance dataset has also been used to determine the probability of extirpation for these native fishes under current conditions.
Microhabitat use of native Santa Ana sucker and arroyo chub in an effluent-dominated southern California stream
Joint-species analysis reveals potential displacement of native fishes by non-native fishes within the Santa Ana River, California
Native Fish Population and Habitat Study, Santa Ana River, California
The Santa Ana River, the largest river in southern California, flows through diverse landscapes, from the high desert to urban and suburban areas in Orange, Riverside, and San Bernardino Counties, stretching approximately 96 miles (154 kilometers) from its headwaters in the San Bernardino Mountains to its mouth at the Pacific Ocean near Huntington Beach. The river is home to the Santa Ana Sucker (Pantosteus santaanae), a species endemic to the basin, and the Arroyo Chub (Gila orcuttii), a native freshwater fish in southern California. To protect these species and other sensitive habitats, the region has implemented Habitat Conservation Plans (HCPs), which are long-term management and conservation strategies for specific areas of land with endangered or threatened species. Native fish, also known as indigenous fish, are species that naturally occur in a specific region or ecosystem and have adapted to the local environmental conditions over time.
Problem Description
The Santa Ana Sucker (Pantosteus santaanae) and Arroyo Chub (Gila orcuttii) are extant native freshwater fishes in southern California. There are numerous threats hypothesized responsible for the poor condition of both fishes in the Santa Ana River. Consequently, the Santa Ana Sucker (Pantosteus santaanae) and Arroyo Chub (Gila orcuttii) are part of the Upper Santa Ana Habitat Conservation Plan, which was developed as a comprehensive program to assist in the development of conservation activities to protect, enhance, and restore habitat for covered species in the watershed. Developing a Habitat Conservation Plan requires sufficient knowledge of the populations of interest to develop plans for their protection and management. The ability to monitor population abundance and habitat availability with some level of confidence is important when developing plans such as the HCP and making management decisions.
Study Questions & Objectives
Study Approach
A stratified random sampling design has been used since 2015 to estimate native fish abundances within the currently known occupied section of the Santa Ana River. Sampling has included the use of backpack electrofishing, seining, and snorkeling methods. Recent surveys have focused sampling efforts on backpack electrofishing methods because they were estimated to be the most efficient at capturing native fishes in the river. As many as 68 random sampling reaches of 50 meters in length have been collected within a sampling year. All reaches have been sampled for fishes and habitat, which has been used to estimate the abundance of native and non-native fishes within the river, and determine how habitat characteristics affect the distribution of these fishes. This native fish abundance dataset has also been used to determine the probability of extirpation for these native fishes under current conditions.