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 salmonproduction variability (an inkling of NEPTUNE in 2030?);

3. Revisiting the 2005 Folger Pass proposal (the biologicalbasis of euphausiid/zooplankton production variability).

1991-2010 Barkley Sound euphausiid/zooplankton study

There have been 161 cruises since March 1991; species, life history stage, sizehave been described for 150,000 euphausiids and 86,000 zooplankton, andabundance 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” offisheries 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 returnvariability.

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

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.

The biological explanation for varying WCVI (Carnation Creek) coho returns

Open circles – observed return; closed circles – predicted return

Biomass T. spinifera (3-5 mm in May), when fish migrate through Barkley Sound, explains why sockeye numbers vary; adjusted R2=0.85.

The biological explanation for varying BarkleySound sockeye returns

Open circles – observed return; closed circles – predicted return

Adult Thysanoessa spinifera biomass, 1991-2009

Annual median biomass has varied by about 100 fold; variationsare 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

Investigative aspects

1. Use Folger Passage Node flourometers to detect increasesin chlorophyll a to identify onset of a phytoplankton bloom;

Operational aspects

1. Ground-truth sensors at Folger Passage Node.

The component that didn't move forward consisted of real-time sampling ofwater properties as well as phytoplankton and euphausiid/zooplanktoncommunities

2. Sample physical and chemical oceanography, and phytoplankton and zooplankton/euphausiid communities,intensively through the bloom;

3. Revert to ongoing euphausiid/zooplankton monitoringafter bloom subsides to monitor mid- and long-term consequences of a given bloom event;

4. Results can provide an understanding of how offshore andinshore oceanographic events generate phytoplankton blooms that are ultimately conducive to euphausiid production.

Revisiting the 2005 Folger Passage Node proposalcont.

1. Creating new knowledge about why biological productivityin the ocean varies;

2. Providing learning opportunities;

3. Facilitating socio-economic empowerment.

Benefits