Offshore killer whale (Orcinus orca) management plan: chapter 6

Appendix I. Terminology – Threat Assessment and PBT Chemicals

Table 5. Details on terms used for assessment of threats to the northeast Pacific Offshore Killer Whale population.

Terms were obtained from the Environment Canada ‘Guideline for Identifying and Mitigating Threats to Species at Risk’ (EC 2006).

TERMS RATING DEFINITIONS
Uncertainty Low Effect of threat is causally linked with decreased population viability and likely will result in failure to meet management plan objectives
Medium Effect of threat is correlated with decreased population viability and negatively impacts management plan objectives
High Negative effect of threat on population viability and/or management plan objectives is assumed or is plausible
Severity Negligible Threat has no detectable effects on the population
Low Effects of threat are sublethal, potentially leading to short-term behavioural changes
Moderate Effects of the threat result in chronic physiological and/or behavioural changes (e.g. potential for long-term displacement from habitat)
High Effects of the threat are lethal
Unknown Available information is insufficient to gauge the degree to which the threat may affect the population viability
Mitigation Potential Low Implementation of measures to mitigate or prevent impacts on population viability, are not practical, or are likely to be unsuccessful.
Moderate Implementation of measures to mitigate or prevent impacts on population viability are feasible, and are likely to be somewhat successful
High Implementation of measures to mitigate or prevent impacts on population viability are currently in place and future measures are likely to be very easy to implement, and are likely to be very successful
Unknown Available information is insufficient to gauge whether mitigation of effects from the threat is possible

 

Table 6. Persistent bioaccumulative toxic chemicals (PBTs) that may pose a risk to Offshore Killer Whales. 

This table was obtained from the final Recovery Strategy for Northern and Southern Resident Killer Whales (DFO 2008).

Pollutant Use/Source Persistent Bio-accumulate Risk
DDT
Dichlorodi-phenyl trichloroethane
pesticide used in some countries, banned in North America, persists in terrestrial runoff 30 years post-ban, enters atmosphere from areas where still in use yes yes reproductive impairment, immunosuppression, adrenal and thyroid effects
PCBs
Polychlorinated Biphenyls
electrical transformer and capacitor fluid, limited use in North America but enters environment from runoff, spills and incineration yes yes reproductive impairment, skeletal abnormalities, immunotoxicity and endocrine disruption
Dioxins and Furans by-product of chlorine bleaching, wood product processing and incomplete combustion. Mills less of a source now. Current sources include burning of salt-laden wood, municipal incinerators, and residential wood and wood waste combustion, in runoff from sewage sludge, wood treatment yes yes thymus and liver damage, birth defects, reproductive impairment, endocrine disruption, immunotoxicity and cancer
PAHs
Persistent Polycyclic aromatic hydrocarbons
by-product of fuel combustion, aluminum smelting, wood treatment, oil spills, metallurgical and coking plants, pulp and paper mills yes no carcinogenic
flame retardants, esp. PBBs and PBDEs
Polybrominated diphenyl ethers
flame retardants; in electrical components and backings of televisions and computers, in textiles and vehicle seats, ubiquitous in environment.  2/3  product PBDEs banned in Europe. Same two products withdrawn from North American marketplace in 2005, but one (deca) product still used globally yes yes endocrine disruption, impairs liver and thyroid
PFOs
Perfluro-octane sulfonate
stain, water and oil repellent (included in Scotchgard until recently), fire fighting foam, fire retardants, insecticides and refrigerants, ubiquitous in environment yes yes but in blood, liver, kidney and muscle promotes tumour growth
TBT, DBT
Tributyltin
Dibutyltin
antifoulant pesticide used on vessels yes yes unknown but recently associated with hearing loss
PCPs
 (Polychlorinated paraffins)
flame retardants, plasticizers, paints, sealants and additives in lubricating oils yes yes endocrine disruption
PCNs
Polychlorinated napthalenes
ship insulation, electrical wires and capacitors, engine oil additive, municipal waste incineration and chlor-alkali plants, contaminant in PCBs yes yes endocrine disruption
APEs
Alkyl-phenol ethoxylates
detergents, shampoos, paints, pesticides, plastics, pulp and paper mills, textile industry found in sewage effluent and sediments moderate moderate endocrine disruption
PCTs
Polychlorinated terphenyls
fire retardants, plasticizers, lubricants, inks and sealants, enters environment in runoff yes yes endocrine disruption and reproductive impairment

References: Primarily Grant and Ross 2002, but also Lindstrom et al. 1999, Hooper and MacDonald 2000, Kannan et al. 2001, Hall et al. 2003; Van de Vijver et al. 2003, Rayne et al. 2004, Song et al. 2005.

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