Elsevier

Fisheries Research

Volume 62, Issue 3, June 2003, Pages 255-293
Fisheries Research

Interactions of Atlantic salmon in the Pacific northwest environment: II. Organic wastes

https://doi.org/10.1016/S0165-7836(03)00064-XGet rights and content

Abstract

The second paper evaluating the environmental risks associated with the culture of Atlantic salmon in the Pacific Northwest addresses organic wastes released from net-pens. It begins with the minor effects caused by dissolved nutrients from organic waste in the water column, and then follows in some detail with the more significant environmental effects created by the deposition of waste onto the benthos under and adjacent to salmon farms. The information is supplemented with new data from case studies to elucidate the relationship between organic inputs from salmon farms, which cause changes in sediment chemistry resulting in predictable biological responses. The paper continues with a discussion of chemical and biological remediation of sediments near salmon farms, and ends with some conclusions on the varying degrees of risk from the presence and accumulation of organic wastes.

Section snippets

Dissolved nutrients in the water column

Salmon excrete 75–90% of their ammonia and ammonium waste across gill epithelia (Gormican, 1989) or in concentrated urea (Persson, 1988, Gowen et al., 1991). Brett and Zala (1975) reported a constant urea excretion rate by sockeye salmon of 2.2 mg N/(kg h). Nitrogen and phosphorus are also dissolved from waste feed and feces during and after descent to bottom sediments. Silvert (1994) suggested that 66–85% of phosphorus in feed is lost in a dissolved form at salmon farms. Johnsen and Wandsvik

Organic enrichment of sediments

Salmon aquaculture in British Columbia grew from a small industry producing less than 2000 MT of Atlantic and Pacific salmon in the early 1980s to 49,700 MT in 1999 (Statistics Canada, 2001). Reviews by Brooks (1996), Winsby et al. (1996), EAO (1997), EVS (2000), and NMFS (2001) describe the benthic response to organic inputs from salmon farms. Considerable information describing benthic effects has been provided by case studies of small farms producing 200–400 MT salmon per cycle in the early

Total volatile solids

There is a diverse literature describing changes in sediment chemistry near salmon farms (Ye et al., 1991, Holmer and Kristensen, 1992, Johnsen et al., 1993, Hargrave et al., 1995, Hargrave et al., 1997, Lu and Wu, 1998, Karakassis et al., 1999). These case studies demonstrated consistent, but variable, increases in sediment carbon under and immediately adjacent to salmon farms. They also suggested that organic biodeposits from fish farming are locally patchy with significant variability in

Predicting biological responses to sedimentation

Plant and animal waste settling onto the seabed is not toxic in and of itself. Therefore, the only relationship that TVS has with infaunal community structure, other than as food, is through its covariance with redox, sulfide, or ammonia concentrations. No literature was found describing the partitioning of the relative effects of oxygen depravation and sulfide toxicity. The toxicity of H2S at high concentrations is unquestioned. Because sulfides are ubiquitous in marine benthic environments,

Chemical and biological remediation of sediments

Chemical and biological recovery of sediments under salmon farms is well documented in the literature by, inter alia, Ritz et al. (1989), Anderson (1992), Mahnken (1993), Brooks (1993b), Lu and Wu (1998), Karakassis et al. (1999), Brooks (2000a), and Crema et al. (2000).

Brooks (2000a) defined two types of remediation:

  • Chemical remediation is the reduction of accumulated organic carbon with a concomitant decrease in hydrogen sulfide and an increase in sediment oxygen concentrations under and

Conclusions

This review supports a thesis that, with the exception of a few shallow poorly flushed embayments, the potential for net-pen enhancement of phytoplankton populations is remote, or non-existent. There also appears to be little risk associated with reduced concentrations of DO associated with salmon culture. A greater risk is imposed on the farm by nutrient rich and oxygen deficient waters, which upwell along the northeastern Pacific coastline and periodically advect into farm tenures. Hydrogen

Acknowledgements

The authors would like to thank William T. Fairgrieve, Robert N. Iwamoto, Colin E. Nash, Michael B. Rust, Mark S. Strom, and F. William Waknitz, the other co-authors of this series of papers, who reviewed and commented on this and the other works. The authors also acknowledge the critiques of nine additional reviewers who read the original manuscripts. Their suggestions were much appreciated.

References (108)

  • H. Tsutsumi et al.

    Benthic faunal succession in a cove organically polluted by fish farming

    Mar. Pollut. Bull.

    (1991)
  • H. Ackefors et al.

    The release of nutrients and organic matter from aquaculture systems in Nordic countries

    J. Appl. Ichthyol.

    (1994)
  • Anderson, E., 1992. Benthic Recovery Following Salmon Farming: Study Site Selection and Initial Surveys. Water Quality...
  • T.U. Bagarinao

    Sulfide as a toxicant in aquatic habitats

    Aquaculture

    (1993)
  • Beveridge, M.C.M., Phillips, M.J., Clarke, R.M., 1991. A quantitative and qualitative assessment of wastes from aquatic...
  • J.R. Brett et al.

    Daily pattern of nitrogen excretion and oxygen consumption of sockeye salmon (Oncorhynchus nerka) under controlled conditions

    J. Fish. Res. Board Can.

    (1975)
  • Brooks, K.M., 1991. Environmental Sampling at Sea Farm Washington, Inc., Net-pen Facility II in Port Angeles Harbor...
  • Brooks, K.M., 1992. Environmental Sampling at the Sea Farm Washington, Inc., Net-pen Facility II in Port Angeles...
  • Brooks, K.M., 1993a. Environmental Sampling at Sea Farm Washington, Inc., Net-pen Facility II in Port Angeles Harbor,...
  • Brooks, K.M., 1993b. Environmental Sampling at Paradise Bay Salmon Farm located in Port Townsend Bay, WA January 1993...
  • Brooks, K.M., 1994a. Environmental Sampling at Sea Farm Washington, Inc., Net-pen Facility II in Port Angeles Harbor,...
  • Brooks, K.M., 1994b. Environmental Sampling at Global Aqua USA, Inc., Saltwater II Salmon Farm Located in Rich Passage,...
  • Brooks, K.M., 1995a. Environmental Sampling at Sea Farm Washington, Inc., Net-pen Facility II in Port Angeles Harbor,...
  • Brooks, K.M., 1995b. Environmental Sampling at Global Aqua USA, Inc., Saltwater II Salmon Farm Located in Rich Passage,...
  • Brooks, K.M., 1996. Assessment of the Environmental Effects of Wastes Associated with the Intensive Culture of Salmon...
  • Brooks, K.M., 2000a. Salmon Farm Benthic and Shellfish Effects Study 1996–1997. Aquatic Environmental Sciences, Port...
  • Brooks, K.M., 2000b. Sediment Concentrations of Zinc Near Salmon Farms in British Columbia, Canada During the Period...
  • Brooks, K.M., 2000c. Database Report to the Ministry of Environment Describing Sediment Physicochemical Response to...
  • Brooks, K.M., 2000d. Report to the Ministry of Environment on the Determination of Copper Loss Rates from Flexgard XI™...
  • Brooks, K.M., 2000e. Report to the Ministry of Environment on Sediment Concentrations of Sulfides and Total Volatile...
  • Brooks, K.M., 2000f. Report to the Ministry of Environment on the Results of the June 2000 Interim Salmon Farm...
  • Brooks, K.M., 2000g. Literature Review and Model Evaluation Describing the Environmental Effects and Carrying Capacity...
  • Brooks, K.M., 2001a. Recommendations to the British Columbia Farmed Salmon Waste Management Technical Advisory Group...
  • Brooks, K.M., 2001b. An Evaluation of the Relationship Between Salmon Farm Biomass, Organic Inputs to Sediments,...
  • Cranston, R., 1994. Dissolved ammonium and sulfate gradients in surficial sediment pore water as a measure of organic...
  • R. Crema et al.

    Recovery of the macrozoobenthic community of the Comacchio lagoon system (northern Adriatic Sea)

    Ophelia

    (2000)
  • Cross, S.F., 1990. Benthic Impacts of Salmon Farming in British Columbia, vol. 1. Available from the Ministry of...
  • Cross, S.F., 1993. Report to the Ministry of Agriculture, Fisheries, and Food on the Oceanographic Characteristics of...
  • Deniseger, J., Erickson, L., 1998. Report on Salmon Aquaculture in the Broughton Archipelago: Results of a Sediment...
  • EAO (Environmental Assessment Office), 1997. Salmon Aquaculture Review. Available from Project Registry, Environmental...
  • O. Einen et al.

    Auditing nutrient discharges from fish farms: theoretical and practical considerations

    Aquat. Res.

    (1995)
  • M. Enell et al.

    Development of Nordic salmonid production in aquaculture and nutrient discharges into adjacent sea areas

    Aquat. Eur.

    (1992)
  • M. Enell et al.

    Environmental impact of aquaculture: sedimentation and nutrient loadings from fish cage culture farming

    Vatten

    (1983)
  • EPA (US Environmental Protection Agency). 1986. Quality criteria for water—1986. EPA 440/5-86-001. US Environmental...
  • EVS, 2000. An evaluation of knowledge and gaps related to impacts of freshwater and marine aquaculture on the aquatic...
  • Findlay, R.H., Watling, L., 1994. Toward a process level model to predict the effects of salmon net-pen aquaculture on...
  • I. Gamenick et al.

    Ecophysiological differentiation of Capitella capitata (Polychaeta): sibling species from different sulfidic habitats

    Mar. Ecol. Prog. Ser.

    (1998)
  • GESAMP (Joint Group of Expert on Scientific Aspects of Marine Environmental Protection), 1996. Monitoring the...
  • Gormican, S.J., 1989. Water circulation, dissolved oxygen, and ammonia concentrations in fish net-cages. M.Sc. Thesis....
  • R.J. Gowen et al.

    The ecological impact of salmonid farming in coastal waters: a review

    Oceanogr. Mar. Biol. Annu. Rev.

    (1987)
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