Mayday Monday - Depleted Salmon Stocks
15 February 2016 - 2:40pm
Primary Threat #1: Depleted Salmon Stocks
The fates of Resident orcas in the Pacific Northwest and their salmon prey are one and the same. The extent of this relationship is reflected in an old tribal adage, "no fish, no Blackfish." The availability and abundance of salmon is the most influential threat to the Southern Residents' recovery. Unless salmon stocks become more abundant, and available, the whales will not recover.
Resident orcas' diet is highly specialized - they rely almost exclusively on salmon, and of that, at least 80% is Chinook. A recent study analyzing the DNA remains of prey in the Southern Residents’ fecal remains confirmed that in the summer months, more than 98% of their diet is salmon – and about 80% is Chinook. This level of specialization indicates that Chinook salmon were at one point much more abundant than now, and may have been the singular supporting resource for a once larger thriving population of whales. Current salmon runs in the Pacific Northwest are approximately 2% of historic levels. This dramatic decline is largely due to human activities related to hydro-electric dams, habitat degradation, overfishing, and hatchery impacts. Birth and survival rates of orcas are clearly related to coast-wide abundance of Chinook salmon. In years of higher Chinook runs, new calves are a source of hope. But, the fact that young Scarlet (J50) is the only calf since 2012 to definitely reach the one-year mark shows that sudden baby booms are short-term trends and that salmon runs may not be stable or large enough to support the whole population the next year. Drops in salmon stocks can have about a year or two of lag time to affect the size of the Southern Resident population. Recovery of both salmon and orcas will take decades. While it's greatly encouraging to see seven new calves added to the population in 2015, we will have to wait and see if they survive the crucial first year, and then live to reproduce and help population growth - an uncertainty largely dependent on how salmon fare in the near future.
The Southern Residents spend their summers in inland Washington and Canadian waters, and travel extensively along the West Coast of the US during the winter and early spring. When prey availability is especially limited, orca families travel over greater distances with more complex movement patterns, spending precious energy foraging for scarce resources. Since winter of 2000, K and L pods have been spending more time inland, later than normal, which is likely related to decreased salmon availability in their normal winter ranges along the outer coast. Expanding critical habitat can help to restore the coastal ecosystem and re-establish the traditional ranges of the Southern Residents.
The National Marine Fisheries Service (NMFS) oversees the legal protection of both the Southern Residents and endangered salmon species, but not nearly enough has been done to restore salmon and the conditions are quickly getting worse for wild populations. Climate change is expected to exacerbate an already serious situation - salmon are known to be sensitive to warm water temperatures, and the El Niño of 2016 is expected to severely impact the ocean food web. Protecting orcas will require protecting salmon, and to make those prey resources available, protecting the Southern Residents' foraging habitat along the West Coast will be essential to their recovery.
Help us expand the Southern Residents' critical habitat by signing our letter urging NMFS to protect this key foraging ground.
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Read more about WDC’s ecosystem recovery efforts to help imperiled salmon populations and the Southern Residents.