Bioaccumulation: A Case Study of British Columbia’s Killer Whales Lesson 1

Killer Whales of British Columbia There are 3 different types of killer whales They have different diets, ranges, languages, behaviour & social organization (Bigg, Ellis, Ford) The three types are Residents, Transients & Offshore killer whales The different kinds do not mate with one another! (Barrett-Lennard)

So much is known because killer whales can be told apart as individuals thanks to the work of Dr. Michael Bigg Dorsal Fin – shape, nicks & scratches Saddle Patch A12, Scimitar, 1941 A33, Nimpkish, 1971 Photos: Jackie Hildering

Resident Killer Whales Eat fish – Mainly salmon The fish can not hear in the range of the calls and salmon has very predictable spawning behaviour This means that residents can afford to be: Very social – they don’t leave their mothers, travelling in matrilines Very vocal – each matriline sounds a little different Because each matriline sounds different, they know exactly who is family and who is not. This if very important for mating! It allows them to avoid inbreeding.

Matriline example Resident killer whales – A30s A30 female 1947 “Tsitika” A6 Male 1964-2000 “Strider” A38 Male 1970 “Blackney” A39 Male 1975 “Pointer” A50 Female1984 “Clio” A54 Female 1989 “Blinkhorn” A75 2001 “Cedar” A84 2005 No name A72 Female1999 “Bend” Know female by DNA

Transient Killer Whales Eat marine mammals The marine mammals can hear them! This means that transients: Must be very quiet until they are sure they are going to get their prey Family structure less stable

Lesson 2

Resident killer whale Salmon Herring Zooplankton Phytoplankton

Transient killer whale Seals Salmon Herring Zooplankton Phytoplankton

Food Web Transient killer whale Resident killer whale Seal Humans Salmon Herring Zooplankton Phytoplankton

Amount of food energy per animal (number of plankton markers) Organism Number Surviving Amount of food energy per animal (number of plankton markers) Total amount of food energy for the species Resident killer whales 2   Salmon Salmon #1 Salmon #2 Etc. Herring Herring #1 Herring #2 Herring #3

Amount of food energy per animal (number of plankton markers) Organism Number Surviving Amount of food energy per animal (number of plankton markers) Total amount of food energy for the species Transient killer whale 1   Seals Seal #1 Etc. Salmon Salmon #1 Salmon #2 Herring Herring #1 Herring #2 Herring #3

Lesson 4

Transient killer whales Persistent Toxins Higher = more Seal Resident killer whales Salmon Salmon Herring Herring Plankton Plankton

Killer whale calf Resident killer whale Salmon Herring Zooplankton Phytoplankton

Total number of marked food pieces Survived (S), Organism Number Surviving Amount of food energy Total number of marked food pieces Survived (S), Died (D) or reproduction and immune system problems (RI) Transient killer whale 1   Seals Seal #1 Etc. Salmon Salmon #1 Salmon #2 Herring Herring #1 Herring #2 Herring #3

Organism Number Surviving Amount of food energy Total number of marked food pieces Survived (S), Died (D) or reproduction and immune system problems (RI) Resident killer whale 1   Salmon Salmon #1 Salmon #2 Etc. Herring Herring #1 Herring #3 Herring #4

Number of toxic plankton markers Organism Number of toxic plankton markers What this means Herring Less than 3 3 to 4 More than 4   Survives Survives but will have reproduction and immune system problems Dies Salmon Less then 4 4 to 6 More than 6 Seals or resident killer whales Less than 5 5 to 8 More than 8 Transient killer whales Less than 8 8 to 12 More than 12