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1
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- Growth and feeding of larval cod
- (Gadus morhua) in the Barents Sea and the Georges Bank
- Trond Kristiansen, Frode Vikebø, Svein Sundby, Geir Huse, Øyvind Fiksen,
Greg Lough, Larry Buckley, and Cisco Werner
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2
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3
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4
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5
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- Three types of models:
- A mechanistic individual-based model for simulating
- bioenergetics, behaviour, and feeding of larval cod
- A general circulation model to simulate the dynamics
- of the ocean (the ROMS model)
- A 3D zooplankton model to simulate the dynamical
- prey field
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6
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7
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- Study how environmental conditions such as:
- Light
- Temperature
- Turbulence
- Food abundance
- affect growth rate of larval fish
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8
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- Specific growth rate (SGR): the amount of weight increase over 24 hours
relative to total weight
- Maximum growth: The physiologically possible growth restricted by
temperature alone
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9
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- Varying light and prey availability at two locations for two different
levels of temperature, and zero turbulence.
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10
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11
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12
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- Varying light and prey availability at the two locations, and increasing
temperature by 2 degrees C.
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13
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14
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- How do light and temperature
for two levels of food abundance and turbulence regulate growth of 5mm
on April 1 and May 1?
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15
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16
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17
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- Varying light and temperature, with estimated prey distribution from the
zooplankton model for larva kept fixed in space.
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18
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19
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- Preliminary conclusions
- Light is limiting feeding and growth prior to mid-April.
- By early May, the number of light hours increases (17/24) and growth is
mainly determined by water temperature.
- High prey densities is not a requirement for growth, but may reduce the
activity level of the larvae and reduce their visibility to predators.
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20
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21
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22
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- Spawning migration:
- Georges Bank: Short spawning migration
- Barents Sea: Very long spawning migration
- Central recruitment hypothesis:
- Barents Sea: Match-mismatch
- Georges Bank: Larval loss
- Temperature-recruitment relations:
- Georges Bank: No clear temperature-recruitment relation
- Barents Sea: Srong temperature-recruitment relationships
- Dominant prey for larvae and early juveniles
- - Georges Bank: Pseudo/Paracalanus spp.
- Barents Sea: Calanus finmarchicus
- Light, climate, spawning and larval growth:
- Georges Bank: Extended spawning period in winter/spring
- Barents Sea: Compressed spawning around equinox and rapid larval and
juvenile growth thereafter
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23
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- Objectives: Use the same model setup for the Barents Sea and the
Georges Bank ecosystems and model drift, dispersal, growth, feeding, survival,
and behavior.
- Identify the major processes
that affect survival variability between ecosystems.
- Simulate a set of years that contributed strongly to recruitment in
each of the ecosystems, and try to understand the major underlying
causes.
- Meet objectives using:
- - Physical model (ROMS)
- - Individual based model (IBM)
- - What about prey fields? Modeled prey fields? Theoretical prey
fields? Observed prey fields?
- - How many prey stages should
be included?
- - What type of atmospheric data to use?
- - +++
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Notes