Download A future initiative for the Folger Passage Node

Learning about the physical, chemical and
biological oceanography that affects euphausiid
(krill) productivity:
A future initiative for the Folger Passage Node
Ron Tanasichuk,
Fisheries and Oceaans Canada,
Pacific Biological Station,
Nanaimo, B. C.
Outline
1. The 20-year euphausiid/zooplankton sampling programme
in Barkley Sound;
2. Learning the biological basis of herring and salmon
production variability (an inkling of NEPTUNE in 2030?);
3. Revisiting the 2005 Folger Pass proposal (the biological
basis of euphausiid/zooplankton production variability).
1991-2010 Barkley Sound euphausiid/zooplankton study
There have been 161 cruises since March 1991; species, life history stage, size
have been described for 150,000 euphausiids and 86,000 zooplankton, and
abundance has been estimated at fine taxonomic levels
M/V Alta: the euphausiid sampling boat
Sampling is done at night with bongo nets
Adult Thysanoessa spinifera biomass, 1991-2009
Annual median biomass has varied by about 100 fold
Knowing T. spinifera biomass variation has
helped us address two of the “Holy Grails” of
fisheries oceanography:
1) the biological basis of recruitment
(production of new spawners) variability for
pelagic fish species such as herring, and;
2) the biological basis of salmon return
variability.
Why WCVI herring recruitment (production of
new spawners, age 3 fish) varies
Biomass of T. spinifera (> 17 mm in August of each of the
first three years of life), and hake predation during the first
year of life explain changes in recruit herring abundance;
adjusted R2=0.94.
Open circles – observed recruitment; closed circles – predicted recruitment
The biological explanation for varying WCVI
(Carnation Creek) coho returns
Number of spawners, stream discharge in January, and biomass
of T. spinifera (> 19 mm in August of the first marine year)
explain why coho numbers vary; adjusted R2=0.89.
Open circles – observed return; closed circles – predicted return
The biological explanation for varying Barkley
Sound sockeye returns
Biomass T. spinifera (3-5 mm in May), when fish migrate
through Barkley Sound, explains why sockeye numbers vary;
adjusted R2=0.85.
Open circles – observed return; closed circles – predicted return
Adult Thysanoessa spinifera biomass, 1991-2009
Annual median biomass has varied by about 100 fold; variations
are not correlated with any measures or indices of ocean
conditions
• To understand how the ocean affects WCVI fish
production, it seems crucial to learn how the
ocean affects euphausiid productivity
• Now that the Folger Passage Node is installed,
we can develop studies to learn what physical,
chemical and biological oceanographic events
are significant w.r.t. euphausiid productivity
Revisiting the 2005 Folger Passage Node proposal
The component that didn't move forward consisted of real-time sampling of
water properties as well as phytoplankton and euphausiid/zooplankton
communities
Operational aspects
1. Ground-truth sensors at Folger Passage Node.
Investigative aspects
1. Use Folger Passage Node flourometers to detect increases
in chlorophyll a to identify onset of a phytoplankton bloom;
Revisiting the 2005 Folger Passage Node proposal
cont.
2. Sample physical and chemical oceanography, and
phytoplankton and zooplankton/euphausiid communities,
intensively through the bloom;
3. Revert to ongoing euphausiid/zooplankton monitoring
after bloom subsides to monitor mid- and long-term
consequences of a given bloom event;
4. Results can provide an understanding of how offshore and
inshore oceanographic events generate phytoplankton
blooms that are ultimately conducive to euphausiid
production.
Benefits
1. Creating new knowledge about why biological productivity
in the ocean varies;
2. Providing learning opportunities;
3. Facilitating socio-economic empowerment.