Sandra O’Neill, Contaminants in salmon
We’ve heard that S and N residents are both eating mostly Chinook. Why are the southern residents more contaminated than the northern residents?
Contaminants in fish are determined by:
- where they live
- what they eat
- how long they are exposed
- how fat they are
Chinook and Coho have elevated [PBDE] because they stay close to shore, while other salmon have undetectable levels. For PCBs are more widely dispersed and present in all salmon, but are highest in Chinook. Puget Sound fish are always much more contaminated than northern fish.
Along the west coast, [PCB] peaks at Puget Sound and are about the same at Skeena (north extreme) and Sacramento (south exptreme). Within Puget Sound, the resident Chinook (blackmouth) are ~3x as contaminated as non-resident Chinook.
Prey quality is also decreasing along W coast. Size is decreasing and kcal/fish is variable. PS fish are smaller and have lower lipid concentration. This means Puget Sound non/resident Chinook will give you ~7/16X PCBs compared to Skeena Chinook!
Peggy Krahn, persistent organic pollutants (POPs) threats to SRKWs
Fisheries and Oceans Canada collected 3 biopsy samples in 2004; NWFSC collected 18 samples in 2006-7.
Most SRKWs have [PCB] exceeding threshold for health effects. Juveniles have much higher concentrations of many POPs (PBDEs, HCGs, and HCB) than adults in their pods. This happened mostly by transfer from their mothers during lactation. The levels are above the estimated threshhold for health effects.
The prevalence of DDT use in CA raises the ratio of DDTs/PCBs above 1. K and L pods have this California signature while J pod doesn’t, which is nicely explained by the observation that J pod haven’t been observed south of Newport, OR.
Teresa Mongillo, predicted contaminant levels in SRKWs
Developed an IB Model which assumes that the Amount of prey consumed = PCB, PBDE in prey + milk – gestation -lactation
Currently there is no change in the [PCB] while [PBDE] is increasing exponentially. Projections were made for different scenarios (variable rates of increase). The model predicts that PCBs will begin to decline after 20+ years; PBDE levels will exceed current PCB levels in 2-40 years.
PCBs increase with age in males, but decreases with offspring in females. In contrast, PBDEs don’t seem to increase but they cluster into groups that are living vs dead… this suggests a potential dose-related effect on calf survival. PCBs decrease with birth order (the first-born gets the biggest load).
Questions:
Rich Osborne: Are heavy metals in such low concentration that they are not of concern? Peggy: Epidermis samples are reserved for stable isotopes and genetics, so there is a sample size limitation. Sandra: Hg levels are slightly higher in Chinook and Coho.
Jeff Lorton: Should we tell our passengers not to eat Chinook? Should we catch/release Chinook across whole region?
Ken Balcomb: Has anyone initiated a study of POPs in local humans, e.g. sports and commercial fishers? There is good analogous study from the Great Lakes.