Southern resident orcas are among the most contaminated marine mammals in the world.
They are highly contaminated by 颅polychlorinated biphenyls (PCBs) in 颅particular, which affect the whales鈥� physical and brain development, immune system and reproductive health.
Ocean Wise and the Environmental Law Centre at the University of Victoria reported in 2020 and 2019, respectively, that out of 51 sites sampled up and down the coast, Victoria Harbour contains the 颅highest 颅concentrations of mercury and toxins such as PCBs, dioxins, flame retardants and 颅plastic stabilizers. The results are based on data from Ocean Wise鈥檚 PollutionTracker, a tool that monitors contaminants in the marine environment along sa国际传媒鈥檚 coast.
Although our harbour isn鈥檛 颅considered critical orca habitat, the toxin 颅concentrations may affect other species. These include some endangered Pacific salmon the 颅endangered orca feed on. In 颅addition, some salmon may feed on other species that spend part of their lives in our harbour.
I鈥檝e seen signs of herring running in the Gorge, and every year, volunteers count the coho returning to spawn in Colquitz Creek. Crabs, shrimp, oysters, and other 颅invertebrates, as well as fish can also be found sheltering in our harbour.
Adult chum eat fish, mollusks and other marine invertebrates. Chinook eat insects and crustaceans when they鈥檙e young and other fish as they grow older and larger.
In 2016, Seattle-area researchers found over-the-counter and prescription 颅medications, cocaine and other illicit drugs in the tissues of juvenile chinook in Puget Sound. Estuary waters near the outfalls of the region鈥檚 sewage-treatment plants were cocktails of more than 80 drugs and 颅personal-care products.
To determine what the drugs might be doing to the fish, the researchers 颅undertook another study. They regularly fed fish food treated with chemicals to the same levels found in the Puget Sound 颅estuaries.
The results, reported in the journal 颅Environmental Pollution in 2018, weren鈥檛 good. The fish grew more slowly, and their metabolisms were so disrupted the fish seemed starved. Blood tests showed that the disruption continued long after the chemical feeding finished.
The response was particularly 颅pronounced in chinook salmon, a species southern resident orcas depend on.
What is found in inland waters would also affect fish swimming in them. For 颅example, Czech researchers found recently that brown trout kept for eight weeks in water laced with trace amounts of 颅methamphetamine similar to levels found in European rivers downstream of 颅cities showed signs of meth addiction.
When the researchers transferred the 铿乻h to 颅uncontaminated water and offered a choice between clean or meth-laced water, the meth-exposed trout selected the 颅drug-laced water 鈥� behaviour that suggests addiction.
The 铿乻h were also less active than trout that had never experienced the drug. The researchers found evidence of the drug in the 铿乻hes鈥� brains up to 10 days after the methamphetamine dosing stopped.
Meth and cocaine may not accumulate in fish tissues nor move up the food chain as PCBs and similar toxins do. Drug addiction, however, might drive 铿乻h to gather near wastewater discharge outfalls in search of 铿亁es, as well as disturb their natural life habits and disrupt population health.
All Pacific salmon start their lives in freshwater. Coho spend at least one 颅winter in freshwater before moving out to the ocean, and sockeye and steelhead spend one to three years in rivers, streams and lakes before heading to the saltwater.
Chinook vary, with some moving oceanwards within weeks of hatching and others remaining in freshwater for up to two 颅winters.
Most southern sa国际传媒 rivers pass through sewage-discharging cities and towns that carry chemical and drug loads.
This means many sa国际传媒 salmon are exposed at a young age to whatever we flush, whether it鈥檚 what we throw out, throw up or dump into our toilets. And if the salmon are exposed, southern resident orcas are likely affected, directly or indirectly.
The Capital Regional District鈥檚 new 颅sewage treatment facility, which began 颅operating in December, provides 颅tertiary treatment before the wastewater is 颅discharged two kilometres out in the strait. Tertiary treatment is one of the highest 颅levels of contaminant-reduction processes and is used to further reduce substances such as metals, organic chemicals and 颅nutrients such as phosphorus and nitrogen.
Depending on the specific processes in place in a facility, it can also reduce the amount of pharmaceuticals and personal care products in the wastewater.
It would be interesting to know how it is helping to reduce the stew of drugs and chemicals the region鈥檚 salmon and orcas are exposed to.
