Study design

Environmental Indicators
Fish and Wildlife monitors spatial and temporal trends in contaminant exposure in Puget Sound fish and macro-invertebrates and the effects of contaminant exposure on the health of these resources. Currently, we monitor environmental indicators1that independently provide information on the contaminant–related environmental conditions of fish and macro-invertebrates in the Puget Sound ecosystem.

  1. Contaminant levels in tissue and bileare measures of exposure to chemical contamination and serve as indicators of environmental quality --- the higher the contaminant exposure, the lower the environmental quality.
  2. Liver disease in adult English sole, measured as the prevalence of toxicopathic3 liver lesions4, can be an indicator of the fishes’ exposure to PAH5 contaminated sediments. Furthermore, the degree of liver disease serves as a general indicator of fish health because reproductive impairment has been observed in fish at sampling sites with elevated occurrences of liver lesions.
  3. Endocrine6 disruption in male fish is measured by sampling their blood for the presence of vitellogenin, a protein associated with egg development. Vitellogenin is not normally present in males and its presence indicates potential disruption of the reproductive system because of exposure to contaminants that mimic estrogen.7
  4. Spawning success, measured by microscopic examination of reproductive organs, is used to estimate percent of fish that recently spawned.

Since 1989, Fish and Wildlife has monitored temporal trends in contaminant levels and prevalence of liver disease in English sole at fixed sampling locations throughout Puget Sound. As of 1999, we started to monitor temporal trends in contaminant exposure in Pacific herring. Historically, we monitored spatial patterns of contaminant exposure in a limited number of species but now we have enhanced our monitoring design to better define spatial patterns for biota from selected areas of Puget Sound. Currently, information on our environmental indicators are collected in three different types of studies.

  1. Baseline Assessment Studies are used to examine temporal trends in contaminant exposure in fish and macro-invertebrates and the prevalence of liver disease in English sole from fixed sampling stations. The number and location of sampling stations and sampling frequency is determined by the life history of the species that is being monitored. Fewer sampling locations are needed to assess species with broad movement patterns that those species with restricted movement patterns. Short-lived species can be monitored annually to document temporal trends whereas long-lived species whose contaminant levels may reflect historic rather than current exposure to contamination should be monitored less frequently or not used for assessing temporal trends.
  2. Focus Studies are used to characterize the spatial patterns (i.e. areal extent) of contaminant exposure for specific geographic location. These studies also provide information on health of the biota (e.g. environmental indicators that measure liver disease in English sole or endocrine disruption in rockfish) in selected embayments of Puget Sound where Baseline Assessment Studies indicate a contaminant problem.
  3. Pilot Studies are used to gather data to test assumptions of proposed Baseline Assessment Studies and Focus Studies. For example, before starting a Baseline Assessment Study, it may be necessary to determine if contaminants accumulate in proposed target species or if factors such as the sex or age of the fish affect contaminant exposure. Pilot studies are only needed if the required data are not available in the literature. Typically pilot studies for contaminant studies compare individuals from a highly contaminated location (worst case) with an uncontaminated location (best case).

In addition to documenting spatial and temporal trends, chemical contaminant data are used to determine whether Puget Sound seafood is safe for human consumption. Fish Component data have been used by managers to issue a health advisory (Sinclair Inlet), to help develop a model for sediment quality standards that protect human health, and to provide data for risk assessments at various Puget Sound locations. The Department of Health (DOH) determines what concentration of contaminants in fish are unsafe for human consumption based on their knowledge of the toxicity of the contaminant, estimates of fish consumption, and duration of exposure. For a given location, Fish and Wildlife assists the DOH by defining the concentration of contaminants that are found in fish over a range of sizes and ages.


  1. A measurement that provides an estimate of the effects of a known factor (toxin, pollutant, environmental management program, etc.) on the state or condition of the environment.

  2. Bile plays an important role in the intestinal absorption of fats. It is a greenish-yellow fluid secreted by the liver and contains cholesterol, bile salts and waste products such as bilirubin. Bile salts aid in the digestion of fats. Bile passes out of the liver via the bile duct where it is stored in the gallbladder and released in response to a fat-containing meal.

  3. Noninfectious pathological conditions or lesions in the liver and kidney which appear to have a positive relationship with contaminant exposure

  4. An injury or other change in an organ or tissue of the body tending to result in impairment or loss of function

  5. A class of chemicals typically formed by burning and common in the environment. PAHs are also common to petroleum products and oil. Although most of these compounds are harmless or mildly toxic, some are carcinogenic.

  6. Pertains to internal secretions, hormonal

  7. A generic term for oestrus producing steroid compounds, the female sex hormones.