Animal  kills

What are animal kills?

A kill is an unexpected and generally short-lived event marked by the conspicuous death of large numbers of fish (e.g. fish kill) or other organism (e.g. usually birds). Animal kills in excess of one event per year are considered indicative of compromised ecosystem integrity according to criteria established during the National Land and Water Resources Audit.

Photo of a fish kill

Photo 1. Example of a fish kill in a coastal waterway (Copyright State of Queensland, Department of Primary Industries).

What causes animal kills?

Photo a: Fish kill at Woolwash Lagoon, Rockhampton, in September 2005. This kill is a result of drying out of the lagoon during drought.

Photo b: Fish kill at Woolwash Lagoon, Rockhampton, in September 2005. This kill is a result of drying out of the lagoon during drought.

Photo 2 (a and b): Fish kill at Woolwash Lagoon, Rockhampton, in September 2005. This kill is a result of drying out of the lagoon during drought. Prior to drying this lagoon held very high densities of fish, but by this stage of drying (max depth 40 cm) there are few fish left. Most had been consumed by pelicans. Most of the fish that remained were too large for the pelicans to handle such as the barramundi and catfish in 2b. (photo’s courtesy of Ross Johnston, James Cook University)

Environmental significance

Fish kills can deplete valuable stocks and render others susceptible to overfishing. Animal kills can also disrupt food web dynamics and the interdependencies between species. They can promote colonisation by noxious species and eliminate species essential to the healthy functioning of communities. Kills are also aesthetically unpleasant because they litter coastal waters with rotten smelly carcasses. The effects of a fish kill may extend further if birds and other predators consume contaminated fish.

Considerations for measurement and interpretation

Animal kills should be reported immediately to either the Environment Protection Agency (EPA), local government, or the Department of Primary Industries. EPA, as lead agency, has a reporting protocol to allow for early response. Kills should be reported in terms of the numbers, species, weight and size distributions. Dead and dying fish/birds as well as samples of sediment and water from the kill site should also be collected as soon as possible after the kill. Other factual information pertaining to the kill site should accompany the samples (e.g. industrial or agricultural activity in the vicinity of the kill, the presence of abnormal materials or unusual colourations in the water or presence of recently dumped rubbish). However, because of the nature of fish kills, dead fish/birds may not be apparent for several days after the impact of the chemical or other factor that caused the mortality. Where disease is expected, animals should be submitted to designated authorities for diagnosis. Monetary and economic valuation of fish kills should be undertaken whenever possible16.

Existing information and data

Government institutions and state agencies keep records of reported fish and bird kills. The NLWRA compiled information on fish kills for a large number of Australian coastal waterways. These data are available in the OzEstuaries database. EPA offices have manuals that explain how to respond to fish kills. Early response is vital if the cause is to be identified and those responsible are to be located. The Fisheries Act1 994 has provisions that can order the restoration of fish stocks or fish habitats following a fish kill. The American Fisheries Association has produced a book detailing procedures for the assessment and valuation of fish kills16.

More information on biota removal/disturbance.

Contributors

John Beumer, Queensland Department of Primary Industries
Ross Johnston, James Cook University

References
  1. Connell, D.W., Miller, G.J. 1984. Chemistry and Ecotoxicology of Pollution. John Wiley & Sons, N.Y.  
  2. Veitch, V. Fish Kills, Sunfish Queensland.  
  3. Wilson, J., Evans, P., and Kelleher, N. 2002. Fish kills in Cockrone Lagoon – Implications for entrance opening of coastal lakes. Proceedings of Coast to Coast 2002 – “Source to Sea”, Tweed Heads, pp. 101-104  
  4. Johnston, R., Sheaves, M. (2006). An analysis of fish kills in Curralea Lake during 2005. Report prepared for Townsville City Council, June 2006.    
  5. Raven, PH., Evert, RF., Eichhorn, SE. (1992) Biology of plants. Worth Publishers, New York.  
  6. Newton, A., Mudge, SM. (2005) Lagoon-sea exchanges, nutrient dynamics and water quality management of the Ria Formosa (Portugal). Estuarine, Coastal and Shelf Science 62(3):405-414.
  7.   
  8. Newton, A., Mudge, SM. (2005) Lagoon-sea exchanges, nutrient dynamics and water quality management of the Ria Formosa (Portugal). Estuarine, Coastal and Shelf Science 62(3):405-414.  
  9. Whitfield, AK. (1995) Mass mortalities of fish in South African estuaries. Southern African journal of aquatic sciences. 21:1-2.  
  10. Watts, J M., Swan, BK., Tiffany, MA., Hurlbert, SH. (2001) Thermal, mixing, and oxygen regimes of the Salton Sea, California, 1997-1999. Hydrobiologia 466: 1-3.  
  11. Derby, CE., Lovvorn, JR. (1997) Predation on fish by cormorants and pelicans in a cold water river: a field and modelling study. Canadian Journal of Fisheries and Aquatic Sciences 54:1480-1493.  
  12. Kaeding, LR., (2002) Factors influencing the distribution of American white pelicans foraging on the Yellowstone River, Yellowstone National Park, USA. Waterbirds, 25:305-311.  
  13. Sheaves, M., Collins, J., Houston, W., Dale, P., Revill, A., Johnston, R., Abrantes, K. (in press) Contribution of Floodplain Wetland Pools to the Ecological Functioning of the Fitzroy River Estuary. Cooperative Research Centre for Coastal Zone, Estuary and Waterway Management, Brisbane.  
  14. Napier, G M, Fairweather, P G and Scott, A C. 1998. Records of fish kills in inland waters of NSW & Queensland in relation to cotton pesticides. Wetlands [Australia] 17[2]:60-71.  
  15. see National strategy for the management of coastal acid sulfate soils – 2000.  
  16. see CSIRO Marine Research, Media and Information fact sheets.  
  17. see The American Fisheries Society.