Salmon return to Carkeek Park to spawn in big numbers

Chum salmon
Deceased Chum salmon are sampled to determine spawning success. Here is a partially spawned female.
Deceased Chum salmon are sampled for a variety of standard data measurements.

As anyone who visited can tell you, the last half of November was amazing in Carkeek Park.  The 2017 Fall run saw about 17% more Chum salmon (338) compared to 2016 (240).  The numbers in the chart below give a quick overview of how exciting it was around the middle of November and how robust the entire season was.  And how do we know these numbers with such confidence?  Continue reading to learn more about Fall salmon runs in this watershed.

Each Fall, CWCAP enters the creeks and tributaries in the Pipers Creek Watershed to collect spawning data from the salmon that naturally die after returning to their home waters. The primary objective is to determine the relative spawning success of salmon in Piper’s Creek and its largest tributary, Venema Creek. Spawning success over time is one measure of the health of the salmon run and the health of the creeks.   Here are the numbers for 2014, 15, 16, and 17.

Here are some details to consider:

  • Anecdotal evidence strongly suggests that this survey undercounts dead fish.  This is the number we discuss when talking about how many fish return from season to season.
  • Storm water flow rate: it is known that extreme energy and water volume associated with storm water moves dead adult salmon from the system to Puget Sound. Fish flushed from the system by stormwater conveyance cannot be estimated and are not represented in this data. 
  • Predators/Scavengers: many salmon carcasses are found each Fall in the brush and wooded areas near the creeks.  Without a comprehensive search, it is likely that the survey team misses numerous carcasses during surveys due to predators and/or scavengers that drag salmon from the near-creek vicinity and are therefore not represented in the data.
  • The survey design is focused on spawning Chum salmon, the species that is imprinted and released into Venema Creek every Spring since the early to mid 80s.  Chum salmon are more fit for spawning success in this system compared to other species of salmon due to its overall life cycle adaptability.  Adaptability to this system’s water quality and habitat is also key to spawning success.
  • Only dead fish are sampled.  Since each of these dead fish are opened with a long incision from vent to throat, fish cannot be double-counted from week to week.  Some dead fish are counted as Remnants since they may be beyond the collection of some data such as Length, Sex, or Spawning due to predation, scavenging or length of time since death.  
  • Live fish are noted for their presence.  On a given day, totals for live and dead fish are discreetly counted and are a good indicator of salmon presence in the Piper’s Creek system for that day.  Seasonal totals of live fish, however, are not possible since this survey has no way of distinguishing between live fish counted from one week to fish that might be alive the next week.
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