The fish fauna in the northern California region constitute a diverse and significant ecological resource. For example, in the Monterey Bay National Marine Sanctuary alone, there are at least 345 fish species distributed across a wide variety of habitats, with each habitat having its own characteristic fish assemblage.

Cordell Bank, Greater Farallones and Monterey Bay sanctuaries all lie within the California Current ecosystem, one of only four major eastern boundary currents in the world. Their cold-temperate fish fauna fall within the Oregonian zoogeographic province, which extends from Point Conception (near Santa Barbara, CA) to Southeast Alaska. Occasionally, southern species from the California Province (south of Point Conception) extend their ranges to central and northern California during warm oceanographic events, such as El Niño and the Pacific Decadal Oscillation (PDO).

Along the West Coast of North America, the distribution of marine organisms varies with latitude, generally due to regional changes in water temperature. Fishes that inhabit the continental shelf and upper slope within California have been grouped into four latitudinal regions:

  • Northern California
  • North-Central California
  • South-Central California
  • Southern California

The three sanctuaries are located in the North-Central region, which spans from Cape Mendocino to San Simeon.

In addition to latitudinal changes in fish assemblages, groups can also be defined by depth, since fishes respond to changes in environmental conditions such as light intensity, temperature and oxygen concentration, factors that are depth-dependent. Ocean processes and physical habitat also greatly influence species composition and distribution.

Conservation and Management Issues

The sanctuaries’ fish communities respond to both natural and human-caused environmental stresses. Although these stressors are listed separately below, synergies among them exist and can be devastating to fish populations.

The diverse fisheries in central California are part of the region’s rich cultural and economic history. The sanctuaries do not currently manage commercial or recreational fisheries; the Pacific Fishery Management Council and California Department of Fish and Game manage federal and state fisheries, respectively.

Productivity and Oceanographic Conditions
El Niño/Southern Oscillation (ENSO) refers to periodic cycling between anomalously warm (El Niño) and cool (La Niña) ocean water temperatures that spread across the equatorial Pacific Ocean. These temperature anomalies indicate perturbations in the ocean and atmosphere that are manifested over broad scales, including the California Current ecosystem.

Biological effects from an El Niño include decreased primary productivity, which often cascades to recruitment failures of ecologically important fish species, particularly rockfishes. In addition, fish species with tropical affinities that are naturally associated with warm water (e.g., billfishes) appear further north.

Like an ENSO event, the PDO comprises a warm and a cool interval, but over a longer period of time. PDOs are periods of sustained climate conditions associated with shifts in ecosystem production regimes in cycles of about 50 years.

Water Quality
Offshore waters in the region are in relatively good condition, but nearshore coastal areas, harbors, lagoons, estuaries and tributaries show a number of problems, including elevated levels of coliform bacteria, detergents, oils, nitrates, sediments and persistent pesticides. These contaminants can have a variety of biological impacts, including bioaccumulation and reduced recruitment of anadramous species.

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Project Database


Ecology and Population Dynamics of White Sharks in the Eastern Pacific: a Case Study

White sharks (Carcharodon carcharias) have been flagged for international protection, yet effective population assessments and management actions have remained hindered by lack of knowledge about the geographical extent and size of distinct populations. Combining satellite tagging, passive acoustic monitoring, visual mark recapture, genetic and stable isotopic analysis we aim to determine white shark critical habitat, migratory patterns foraging ecology and population structure.


Fine scale, long-term tracking of adult whites sharks

This project is designed to capture and affix near real-time satellite transmitters to the dorsal fins of 5 male and 8 female white sharks from the Farallon Islands. The sharks will be captured via hook-and-line, raised from the water on a large hydraulic platform and tagged before being released. Data will be collected and monitored over the next 4-6 years, via the ARGOS satellite array.


Midwater Trawl Pre-recruit Survey

The NOAA National Marine Fisheries Service (NMFS) Southwest Fisheries Science Center (SWFSC) Fisheries Ecology Division has conducted annual surveys of the distribution and abundance of pre-recruit stage rockfish as well as other commercially important species such as Pacific whiting in order to provide year-class strength information that can be used in the fisheries management process. Hydgrographic conditions present during the surveys are also examined.


Tagging of Pacific Predators (TOPP)

The Tagging of Pacific Pelagics (TOPP) research program aims to understand the migration patterns of large predators in the North Pacific basin and how these animals act and interact in their open ocean habitats. By using satellite tagging techniques, TOPP researchers follow the movements of different species across multiple trophic levels (i.e., the food web) and in relation to physical oceanographic features in order to piece together a whole ecosystem picture.