Environmental Impacts of Salmon Farms: Lessons from New Brunswick

Inka MilewskiScience Advisor

Conservation Council of New Brunswick

June 27, 2011Shelburne, Nova Scotia

Environmental Impacts of Salmon FarmsKnown potential impacts

include:

• Increased suspended solids, turbidity and sedimentation

• Nutrient loading• Degradation of water quality from hazardous materials• Impacts to fish and fish habitat• Disease transmission• Invasive species, which could alter ecosystem

dynamics• Interference with traditional use of resources• Disruptions of wildlife and wildlife habitat,

including migratory birds and species at risk• Impacts of odour and noise on humans

Source: Transport Canada. 2011. Environmental Assessment Screening Report for proposed sites in St. Mary’s Bay

Environmental Impacts of Salmon Farms

• By volume, largest component of waste released from a salmon farm is organic (fecal and uneaten feed) waste and nutrient (nitrogen and phosphorus)

Carbon and nitrogen releases to the L’Etang Inlet, New Brunswick 2002

Sources Carbon (mt per year)

Nitrogen (mt per year)

Salmon Farms – 22 farms(APL 4.44 million fish)

949 2372.5

259.1657.0

Sewage plant (servicing 1200 people) 51.1 10.9

Pulp Mill 138.7 4.1

Fish plant (sardine processing plant) 1525.7 273.7

Runoff from land 299.3 10.95Precipitation - 18.2

Source: Strain and Hargrave. 2005. Salmon aquaculture, nutrient fluxes and ecosystem processes in southwestern New Brunswick. In. Hargrave (ed.) Environmental Effects of Marine FInfish Aquaculture: The Handbook of Environmental Chemistry Vol 5.

Impacts of Organic (Carbon) Waste

• Sediments and the water column above become oxygen depleted and toxic

• Diversity of animals in and on the sediment drops; white bacterial mats cover the bottom

• Food chain connecting the benthic (bottom-dwelling) and pelagic (free-swimming) communities becomes uncoupled

• Increase in annual seaweed biomass

• increased incidence of toxic phytoplankton blooms

• localized oxygen depletions• loss of perennial submerged

aquatic vegetation (e.g., rockweed, eelgrass)

• a shift from filter-feeding (clams, mussels) to deposit-feeding (worms) animals

• increased disease in fish, crabs, and/or lobster

Impacts from Nutrient (nitrogen and phosphorous)

Waste

Crow Harbour/Penn Island, New Brunswick Study 2002-2004

Control site

Former Fish Farm Site

Crow Harbour/Penn Island, New Brunswick Study 2002-2004

• July 2000 site ~ 295,000 smolt put into 21 net pens covering an area of ~19 ha

• April 2002 harvesting began• July 2002 final feeding • August 2002 last fish

harvested • August 24, 2002 benthic

survey began ~ 5 months after most intensive feeding period and 3 weeks after last fish harvested

• Sampled again on August 27, 2003 and August 23. 2004

Sediment core sample coming on board and testing

2002 Crow Harbour benthic samples 2002 Control Site benthic samples

Black sediments indicate a lack of oxygen and the presence of anaerobic bacteria.

Reference/Control site 2003

Penn Island/Crow Harbour farm site 2003

Penn Island/Crow Harbour farm site 2004

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Sediment Eh at a former fish farm in Crow Harbour and a reference site (mean values of 3 samples) – 2002-2004

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Surface Sediment Sulfides at a former fish farm in Crow Harbour and a reference site (2002-2004)

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diversity did not recover at the farm site after two years

Environmental Monitoring of Salmon Farms

• only one environmental measure is monitored – sulphides in sediments

• DFO has not defined a sulphide limit that results in mandatory regulatory action ; HADD authorization may be required at 4500-6000 μM

• 40-60% biodiversity reduced at 500 to 1500 μM sulphides

• 60-70% reduced at 1500-3000 μM

• 70-90% reduced at 3000-6000 μM

• 90% reduced > 6000 μM

Environmental Monitoring of Salmon Farms In New Brunswick

• Prior to 2006, remediation plans were required when sulphides reached 1300 μM

• In 2006, remediation required when benthic sulphides reach 1500 μm

• Site must do more monitoring and submit report when sulphides are 3000-4500 μM and may be required to get HADD authorization from DFO

• Annually, 20% of NB farms require remediation plans

2006 Salmon Farm Sites

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Benthic Monitoring Results (2002-2010) for NB Lease Site 342 (Passamaquoddy Bay)

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NB Remediation Action Level

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Benthic Monitoring Results (2002-2010) for NB Lease Site 059 (Deer Island)

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2006 NB Action Level2001 NB Action Level

2009: 2111.7 μM sulphides

2010: 1442 μM sulphides

Control site

Former Fish Farm

Nova Scotia Environmental Monitoring Program (EMP)

• First EMP began in 2002

• Plan was updated in March 2011

• EMP is focused on monitoring sulphides

• EMP approach is “increased risk requires increased monitoring”

• Sites with ≥ 50% of sampling stations with ≥1500 μM sulphides need more sampling and must adjust their Best Management Practices (BMP) to improve site performance

• Sites with ≥50% of sampling stations with ≥3000 μM of sulphides need more sampling and operator must submit a mitigation plan for maintaining or increasing production levels

• Sites with ≥70% of sampling stations with ≥6000 μM sulphides must work with regulators to examine mitigation options; some site may require DFO authorization to allow a (HADD) harmful alteration, disruption or destruction of fish habitat on the site

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Nova Scotia Environmental Monitoring Re-sults Spectacle Island Farm Site – Port Mouton

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Nova Scotia Environmental Monitoring Results

Sandy Point – Shelburne Harbour

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Nova Scotia Environmental Monitoring ResultsBrier Island/Westport

Beyond the farm impactsBay-wide (Cumulative) Effects from multiple salmon farms

Sampled 1994-1999 examined sediment carbon, microbial

biomass and biological diversity 1994-95 results showed area was

strongly impacted 1996-1997 salmon farming stopped

due to ISA outbreak; Re-sampled in 1997 and 1999; carbon

and bacteria levels declined, no recovery in the biological community

farm operations had an effect on benthic habitat beyond the farm area

Pohle et al. 2001. Assessment of regional benthic impact of salmon mariculture within the Letang Inlet, Bay of Fundy. ICES Journal of Marine Science 58: 417–426. 2001

• For Lime Kiln Bay, salmon farms release 3.3 times more nitrogen and 1.6 time more carbon is cycled naturally in the water column and sediments.

• substantial changes to the functioning of the ecosystem have occurred due to the presence of the salmon farms

• Even in a larger, less intensively farmed area like the Campobello / Deer Island, fluxes of carbon and nitrogen from salmon aquaculture are 10 and 16 %, respectively, of those due to natural processes.

• Local impacts can be much greater than those measured on large scales

Source: Strain and Hargrave. 2005. Salmon aquaculture, nutrient fluxes and ecosystem processes in southwestern New Brunswick. In. Hargrave (ed.) Environmental Effects of Marine FInfish Aquaculture: The Handbook of Environmental Chemistry Vol 5.

Beyond the farm impactsBay-wide (Cumulative) Effects from multiple salmon farms

Regulations and Management of Impacts? Inadequate and Incomplete

• information for managing ecosystem effects are currently incomplete

• multiple measures will be the most effective for managing ecosystem effects of aquaculture

• management focused primarily on near-field and site-specific regulatory applications

• far-field and cumulative effects could occur and will require new or modified management tools

• Benthic monitoring is less suitable for farfield monitoring

• finfish aquaculture has the potential to alter the trophic (food web) status of bays

• Mass balance calculations can be used to estimate the portion of aquaculture wastes to a system compared to nutrients from other sources

Our Oceans and Coasts in Trouble• A decline in many fish stocks

has occurred on the Atlantic and Pacific coasts as a result of commercial overexploitation.

• Industry and development have, or are threatening to, impact most ecosystems.

• The coastal zone is particularly vulnerable and is of concern as these areas are considered highly productive ecosystems.

Need for sustainable aquaculture

• Activities that do not degrade the ecosystem on which they depend including:– preserving the form and function (ecological

relationships) of natural systems– preventing nutrient, chemical and biological

pollution– ensuring no net loss of protein

Source: Bardach, 1997: Sustainable Aquaculture. New York; John Wiley & Sons Costa-Pierce, 2002. Ecological Aquaculture: The evolution of the blue revolution Oxford: Blackwell Science