SoundHAB: South Puget Sound fish kill and increasing phytoplankton abundance in the usual areas of Puget Sound

[Rensel]

A minor fish kill of yearling coho salmon has occurred at the Squaxin Island
Tribal net pens in Southern Puget Sound commencing from 2 days ago, possibly
associated with a bloom of Phaeocystic sp., a harmful or noxious species not
usually associated with fish kills and not previously reported from Puget
Sound fish kills in the past.   Fish are reared for a short term in these
pens before release to enhance fisheries in the South Puget Sound an
elsewhere in cooperation with the Washington State Dept. of Fish and
Wildlife.  Managers are assessing the situation and may release the fish in
the near future. 

 

This reportedly was not a major fish kill and Northwest Indian Fish
Commission fish pathologists have inspected the fish, observed gill damage
and made management recommendations.     If more information becomes
available, we will pass it on.  

 

Meanwhile many of the usual suspect areas are experiencing increased
phytoplankton biomass concurrent with the first sunny and relatively warm
weather of our year.  NWFSC NOAA workers and fish farmers in North Puget
Sound report that species composition is mainly diatoms where it has been
sampled.  However this is based on limited sampling and not the US/Canada
border areas or Samish and Padilla Bay areas that are often bloom inittition
areas for Heterosigma. 

 

Tides are relatively large this week which tends to reduce the risks of
major blooms in our mixed channel areas.  Vertical stratification near river
mouths and throughout all north Puget Sound north and east of Orcas Island
and the South Strait of Georgia is in some cases less influenced by tidal
induced mixing.  The plot below shows what may be an early peaking discharge
of the Fraser River are factors of concern for fish killing Heterosigma
blooms, as occurred in May 2007 and was associated with the extremely poor
return of Fraser River sockeye in 2009.  Historically, Heterosigma blooms
often first occurred around July 4th, but in recent years blooms have
occurred much earlier.   Unfortunately, no sampling is being conducted in
the open waters of South Strait of Georgia at this time to the best of our
knowledge although typically sockeye smolts by the millions are flooding out
of the river into the South Strait of Georgia.   

 

Thank you to Jeff Dickison of the Squaxin Island Tribe for reporting this
event. We invite all participants to report harmful blooms using SoundHAB
list serv and especially fish kills to please report such events as soon as
possible so that other researchers can cooperate and contribute.  This is
especially important for species of harmful algae that previously have not
been implicated in nusiance or toxic blooms in our area in the past. 

 

Yesterday's Modis Satellite chlorophyll a image from an afternoon time
period.  MODIS NPP, 0.0125 degrees, West US, EXPERIMENTAL

(mg m^-3) 2011-05-18  (not adjusted for river plume effects). 

 

Description: C:\Users\Rensel\AppData\Local\Microsoft\Windows\Temporary
Internet Files\Content.Outlook\F4FHUS15\chlorophyll 18May11.jpg

 

Fraser River Discharge (solid line), Mean historical flow (dashed) and upper
quartile of historical flow (dashed-dotted)

 

Description: C:\Users\Rensel\AppData\Local\Microsoft\Windows\Temporary
Internet Files\Content.Outlook\F4FHUS15\Fraser 19May11.jpg

 

J.E. Jack Rensel Ph.D.

Rensel Associates Aquatic Sciences

4209 234th St. N.E.

Arlington WA 98223

360-631-6538

Jackrensel at att.net

 

 

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