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Nov 16 2010

DFO – monitoring since 1986 – not enough information yet!

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Subject: High pre-spawn mortality

Dear Laura Richards,

Many people are writing to me about extremely high pre-spawn mortality in the lower Shuswap and the Adams Rivers.

Can you pass on to me what DFO is doing in response to this so I can inform them? Given Kristi Miller’s work suggesting a novel virus is seriously impacting, perhaps even killing, the majority both adult and juvenile Fraser stock sockeye it would seem very important to do comprehensive pathology on this event.

People are writing me because they claim they never get answers from DFO.

Thank you very much,
Alexandra Morton

Sockeye pre-spawn mortality

—— Forwarded Message
From: “Richards, Laura”
Date: Wed, 10 Nov 2010 16:19:04 -0800
To: Alexandra Morton
Cc: Mike Lapointe, Brian Riddell, Stewart Johnson, Susan Farlinger, Mark Saunders,

Conversation: High pre-spawn mortality
Subject: RE: High pre-spawn mortality

Dear Alexandra

I would like to respond to your e-mails dated November 2, 2010, and December 7, 2010, regarding reports of extremely high pre-spawn mortality of sockeye in the Lower Shuswap and Adams Rivers.

Before commenting on the Department of Fisheries and Oceans (DFO) monitoring and assessment activities, it’s important to distinguish between the two categories of mortality experienced by sockeye along their migration path and (DFO) programs to assess each. Pre-spawning mortality (PSM) is defined as female sockeye mortality that occurs within a spawning population that have successfully migrated to their spawning grounds but which die prior to completion of spawning. En-route mortality (ERM) refers to mortality occurring within the freshwater riverine environment that is not attributable to direct fishery related removals or to PSM.

DFO annually monitors all major Fraser River sockeye salmon populations to determine spawner abundance and spawning success. During spawner enumeration surveys, an estimate of spawning success is generated for each spawning site based on female carcass assessment. As PSM is expressed as the percentage of the total estimated female spawning population that did not successfully spawn, these values cannot be calculated with any level of accuracy until spawning is complete and spawning estimates are available. Assessment programs are ongoing and it will be several weeks before spawning estimates become available.

This year field staff reported high numbers of unspawned moribund females during the early and middle portions of the Lower Shuswap River Sockeye run. However, at this time it is impossible to put these observations into context as PSM is typically higher on the early to mid portion of the run. PSM in the range of 10% is not uncommon for Fraser sockeye and given the magnitude of the return experienced this fall, even normal levels of PSM could potentially represent a large number of observed carcasses.

Estimates of en-route mortality (ERM) are difficult to obtain due to the size and water conditions of the Fraser River. En-route mortality has been periodically assessed for some Fraser sockeye stocks via the application of acoustic or radio tags and tracking the progress of tagged fish along their migratory route. Estimates of ERM are limited by the number of fish that can be tagged and at a spatial scale by the number of receivers along the Fraser River. In 2010, DFO in partnership with other researchers, applied acoustic tags to sockeye in both marine approach areas and in the lower river to obtain estimates of ERM. Given that assessment is ongoing, it is too early to report on en-route mortality levels for 2010.

Tissue biopsies were also collected from the radio-tagged fish for microarray analysis. Additional samples (RNA, tissue, blood, gill, brains, and tissues for histology) were collected from returning adults in Johnstone Strait, the lower river and on the spawning grounds. Samples collected in 2010 have not been processed yet.

DFO’s Environmental Watch Program, in collaboration with other internal and external researchers, is investigating the impact of different environmental factors on the migration success of Pacific salmon in fresh water. Annual activities include biological, energetic, physiological, and disease assessments of migrating and spawning adult Fraser sockeye salmon. In 2010, all major stocks were assessed, but effort focused on late run sockeye behaviour and consequences (e.g. ERM and PSM) for the development of descriptive and predictive modeling for fisheries management.

In addition, DFO’s Aquatic Animal Health section has been monitoring Fraser Sockeye salmon populations at Nadina River and Weaver Creek for the presence of pathogens and disease annually since 1986. In early September 2010, samples of moribund sockeye salmon from Nadina River spawning channel tested negative for viral pathogens (OIE methodology) and tested positive for the presence of Aeromonas hydrophila, a bacterium ubiquitous in the Fraser River and common in spawning sockeye. This bacterium is normally considered to be of low virulence, but can be a problem in fish that have a compromised immune system. Samples of tissues submitted for histology have not yet been analyzed. Sockeye sampled from Nadina River in late September tested positive for infectious hematopoietic necrosis virus (IHNV). IHNV has been reported in post-spawned fish in the Nadina River sporadically since 1986. There is no evidence that IHNV has an effect on pre-spawn mortality rates. The analyses of 2010 samples are ongoing with an expected completion date of spring 2011.

As you can gather, DFO has a significant program of monitoring and analyses underway related to determining the levels of pre-spawn mortality and its potential causes.

Thank you for writing to me with your concerns.

Sincerely,

Laura Richards

Dr. Laura Richards
Regional Director Science | Directrice régionale des sciences
Fisheries and Oceans Canada | Pêches et Océans Canada
Pacific Biological Station | Station biologique du Pacifique
3190 Hammond Bay Rd, Nanaimo, BC, Canada V9T 6N7
Laura Richards
Telephone | Téléphone 250-756-7177
Facsimile | Télécopieur 250-729-8360
Government of Canada | Gouvernement du Canada

3 comments

  1. priscilla judd

    Something I just thought about:
    Since there is a virus as confirmed in DFO’s e-mail – what happens when DFO chop salmon in half to count them?

    When I prune a diseased tree, I clean the pruners with alcohol between cuts so that I don’t spread disease. Is DFO cleaning their knfe between cuts? Are they spreading disease by cutting dead salmon in half?

    The virus kills the salmon but does it continue to live on in the dead salmon? Can the virus multiply in dead salmon? Can it spread to the smolts that live in the water with dead salmon? Is the disease over when the salmon tissue decomposes?

    Was it Government investigators who spread the Avian flu between the chicken barns?

    Is DFO protecting our salmon when they chop dead salmon in half?

       0 likes

  2. admin

    Dr. Laura Richards, Regional Science Director writes:

    “In early September 2010… sockeye salmon from Nadina River … tested positive for the presence of Aeromonas hydrophila” “… in late September [sockeye salmon] tested positive for infectious hematopoietic necrosis virus (IHNV). IHNV has been reported in post-spawned fish in the Nadina River sporadically since 1986. ”

    (Didn’t Dr.Moton ask about pre-spawn mortality?)

    “DFO has a significant program of monitoring and analyses underway related to determining the levels of pre-spawn mortality and its potential causes.”

    It appears that DFO has a significant monotoring program – but they always need more information and when they do say something it doesn’t really tell us enough:

    Where has “IHNV” been “reported”? Where is Nadina River? It’s not on my map.

    Does DFO’s e-mail give any information about “extremely high pre-spawn mortality in the lower Shuswap and the Adams Rivers”? Wasn’t that was the subject of Dr. Morton’s email?

    Apparently people are telling Alexandra Morton they never get answers from DFO – I can see why they say that.

       0 likes

    1. admin

      I have been told that Nadina River is up near Burns Lake. Is that in the Lower Shuswap and Adams River?

      DFO has not answered the question.
      Does that give me confidence in DFO’s scienctific monotoring?
      If DFO has not collected information related to pre-spawn mortality in the Lower Shuswap and Adams River (the largest sockeye run in BC) DFO has overlooked it’s conservation objective. If DFO has collected Adams River data in the same way they collected Nadina River data – why have they not referred to it in their e-mail reply?

         0 likes

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