Modelling advection of cod eggs and larvae on the Newfoundland Shelf

In this thesis I investigate the drift and retention of cod eggs and larvae on the Newfoundland Shelf using two different mathematical methods. The first is an analytical model that solves the advection-diffusion equation for a patch of larvae in a spatially homogeneous, time-dependent current for the proportion of larvae retained on the shelf. We show that there is a weak correlation between retention of larvae and recruitment of northern cod. Furthermore, we demonstrate the sensitivity of retention to location of the larvae relative to the shelf break. -- In the second method we use a two-dimensional velocity field to study the interannual variations of cod egg and larval dispersion on the Newfoundland and Labrador shelf. This model uses a steady state mean flow derived from a diagnostic calculation of objectively analysed density data for the Northeast Newfoundland Shelf. Time-dependent currents are generated using a slab model driven by observed winds, following the approach of Pollard-Millard (1970). We study the advection of the eggs and larvae using numerical Lagrangian drifters seeded throughout the Newfoundland Shelf region. We identify favourable and unfavourable zones of retention on the Newfoundland shelf. We show that northerly, shelf break spawning locations are more favourable than southerly shelf break spawning locations for northern cod (Gadus Morhua in NAFO divisions 2J3KL).

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