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Biodiversity along the West Coast of Vancouver Island: Lessons learned and application to the

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Title: Biodiversity along the West Coast of Vancouver Island: Lessons learned and application to the


1
Biodiversity along the West Coast of Vancouver
Island Lessons learned and application to the
Strait of Georgia
Ron Tanasichuk, Pacific Biological
Station, Nanaimo, B. C. Email Ronald.Tanasichuk_at_d
fo-mpo.gc.ca Ph. 250-756-7197
2
Biodiversity defined Wikipedia Biodiversity
is the degree of variation of life forms within
a given species, ecosystem, biome, or an
entire planet. But from an ecosystem
perspective, it's important to remember that its
not just the biodiversity, but also how plants
and animals interact. The monitoring of
biodiversity variations and species interactions
along the West Coast of Vancouver Island has
given us novel insights of the biological bases
of fish production variability, and the
approaches used on the West Coast provide a model
for monitoring biodiversity and ecosystem
production in the Strait of Georgia.
3
WCVI (La Perouse Bank) Study Area
4
Fish production variability along the WCVI
largely revolves around the production
variability of one species of euphausiid
(krill, Thysanoessa spinifera)
The largest T. spinifera measured was 32 mm long
and weighed 340 mg. It is not an overstatement
that T. spinifera is the link between the sun
and the production of many fish species on the
WCVI.
5
WCVI euphausiid/zooplankton monitoring programme,
1991- present
F
We have done 177 cruises since 1991 and have
measured and weighed over 162,000 euphausiids and
90,000 zooplankton
6
T. spinifera biomass, 1991-2011
Annual median biomass has varied by 120-fold
The proportion of total zooplankton biomass (open
circles) accounted for by euphausiids has changed
dramatically
7
To learn about the variations in the productivity
of any animal population we have to
consider 1) characteristics of the population
itself (eg. parental abundance, numbers of
brothers and sisters) 2) variations in prey
availability 3) variations in competitor
abundance and, 4) variations in predator
abundance. Investigative science is based on
hypothesis testing, using observation. We
collected data for a number of years, even
over several decades, so that we could test
hypotheses related to the biological basis of
herring and salmon production variability.
8
An important fish predator and possible
competitor Pacific hake
9
Hake biomass variability
Hake biomass can range from insignificant to over
1,000,000 tonnes
10
Emerging potentially important predators
Humpbacks and sea lions are recovering
dramatically
11
Herring
WCVI and Strait of Georgia herring show differing
trends
12
Prey availability for herring, 1991-2011
T. spinifera longer than 17 mm are the most
important prey for herring this prey accounts
for about 7 of the total biomass of zooplankton
August is the critical period for energy
accumulation euphausiid peaks occur in August
(open circles) in 6 of 21 years biomass has
varied by a factor of 800.
13
The biological explanation for varying WCVI
herring recruitment
The biomass of T. spinifera gt 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 (first-time spawners,
Age 3) abundance.
Open circles observed recruitment closed
circles predicted recruitment
14
The biological explanation for varying survival
rates of adult WCVI herring
Survival rates decrease (mortality rates
increase) with age, presumably because fish
become progressively less efficient metabolically
with age, but also decrease as the August biomass
of T. spinifera longer than 17 mm declines.
15
The biological explanation of WCVI growth
variation
The size of recruits is determined by T.
spinifera biomass in August of each of the first
three years of life. Size-at-age of older fish
is essentially determined by recruit size and is
affected to a lesser extent by T. spinifera
biomass in August.
7
6
5
4
3
Numbers are age
16
The salmon populations we consider
17
Barkley Sound Juvenile Salmon Studies
Goal of the research was to learn about
distribution, migration timing, diet, and
hatchery/wild fish interactions
18
Variations in euphausiid prey for coho
T. spinifera longer than 19 mm account for about
7 of the total biomass of zooplankton biomass
has varied by a factor of 700 peaks occur in
May (open circles) in 5 of 21 years.
19
The biological explanation for varying Carnation
Creek coho returns
Closed circles observed return open circles
predicted return
Number of spawners, winter stream discharge, and
marine prey (T. spinifera gt 19 mm in May when
fish enter the ocean) explained why total coho
numbers vary.
20
Variations in euphausiid prey for sockeye
T. spinifera 3-5 mm account for about 0.05 of
the total biomass of zooplankton biomass has
varied by a factor of 400 peaks occur in May
(open circles) in 6 of 16 years.
21
The biological explanation for Somass River
sockeye return variability
Somass River sockeye forecasts are based on the
observation (Tanasichuk and Routledge 2011) that
return variability is explained by variations in
the biomass of 3-5 mm T. spinifera in May, when
fish are migrating through Barkley Sound.
Forecasts were inaccurate in 2010 and 2011.
Closed circles observed return open circles
predicted return dashed lines 50 confidence
interval.
22
Age-specific responses to T. spinifera biomass
suggest that each lake contains not one but six
sockeye populations
x - 2010 return year o - 2011 return year
dashed lines - 50 confidence limits. 2011
forecast was inaccurate because of ages 3.2 and
4.2 returns. Results for Sproat Lake are
comparable for these for Great Central Lake.
23
Retrospective analysis of performance of
euphausiid-based forecasts of Smith Inlet
sockeye return
Closed circles observed return open circles
predicted return dashed lines 50 confidence
interval. WCVI euphausiid biomass
measurements may have broader implications.
24
Fraser River sockeye
Total returns of the 19 monitored populations
show a range of response to the effects of stock
and T. spinifera biomass closed circles -
observed, open circles predicted. The low
return for 2009 was predicted in this analysis
suggesting that the discrepancy between the
conventional forecast and the observed return was
a consequence of an inaccurate forecasting
methodology rather than a real biological event.
25
WCVI Summary and Conclusions
1. The lesson we have learned is that studies
which use time series of observations of
population characteristics, prey, competitors and
predators provided the information that we needed
to discover the biological bases of WCVI herring
and salmon production variability 2. It
appears that some of the WCVI work has
implications at a regional scale 3. Based on
the success of the WCVI studies, we can apply the
WCVI study methodology to create a monitoring
programme in the Strait of Georgia. 4. We will
be able to use the results to learn the
biological bases of production variability and
then be able to make informed decisions about
biological resource use to optimize ecosystem
health and benefit to communities.
26
Community-based Strait of Georgia nearshore
marine ecosystem monitoring programme An
invitation
Community locations are almost perfect for
comprehensive programme need more sampling
locations in Gulf Islands. Work would pattern
after Barkley Sound study and be bi-weekly (April
October) to monitor food, diet, distribution
and abundance of hatchery and wild salmon.
Sampling should beach- and purse seine fish
collections and zooplankton sampling.
27
Nanaimo River chum distribution
Nearshore work in the late-70's suggests that
juveniles may be highly concentrated in very
shallow water suggesting that this is an
important area to investigate.
28
Proposed Strait of Georgia beachseine sites
154 sampling sites
29
Google App technology can be used to input field
data at the time of sampling using smart phones
or tablets
This means that data will be archived
instantaneously and freely available.
30
Strait of Georgia zooplankton monitoring transects
47 sampling sites
31
Summary and Conclusions
1. Long-term monitoring of ecosystem diversity,
including species interactions and variations in
distribution and over time, are crucial to
understanding, managing, and benefitting from
biological resources 2. Studies of the
biological bases of herring and salmon production
variability on the WCVI provide a framework for
such work in the Strait of Georgia and, as
importantly, show that these types of studies can
help us learn about ecosystem structure and
function 3. The proposed Strait of Georgia
ecosystem monitoring programme is an absolutely
unique opportunity for the communities to share
in learning about the biology of the Strait, and
contribute to optimizing ecosystem health and
benefit to the communities.
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