Mj. Tremblay et al., DRIFT OF SEA SCALLOP LARVAE PLACOPECTEN-MAGELLANICUS ON GEORGES BANK - A MODEL STUDY OF THE ROLES OF MEAN ADVECTION, LARVAL BEHAVIOR AND LARVAL ORIGIN, Deep-sea research. Part 2. Topical studies in oceanography, 41(1), 1994, pp. 7-49
The drift and exchange of sea scallop larvae (Placopecten magellanicus
) on Georges Bank is investigated by tracking particles in three-dimen
sional flow fields consisting of the semidiurnal tidal current and aut
umn mean circulation on realistic topography. Three composite flow fie
lds are considered, each forced by non-linear tidal current interactio
ns, seasonal-mean density gradients and seasonal-mean wind stress. The
around-bank flow rates are in approximate agreement with the observed
residual gyre, while the cross-isobath currents in the flow fields ar
e consistent with observations only in being generally weak. In most c
ases it is unclear whether the discrepancies arise from observational
uncertainties or from model approximations. In the simulations the par
ticles are given the behavior and planktonic period expected of sea sc
allop larvae. Particle star-ting positions correspond to the three maj
or scallop aggregations: the Northeast Peak (NEP), the Southern Flank
(SF), and the Great South Channel (GSC). Simulations are run to examin
e the sensitivity of the particle trajectories and settlement numbers
to aspects of larval biology (vertical distribution, ascent and descen
t rates, search times, growth and mortality rates), and to various flo
w field components. The pattern and extent of larval exchange and sett
lement are most sensitive to the duration and depth of planktonic drif
t, gyre strength, weak cross-isobath flow, and mortality rate. The sim
ulations indicate significant larval exchange among the three aggregat
ions, with self-seeding possible for the GSC and NEP, and unlikely for
the SF. Given the high retention of particles on Georges Bank as a wh
ole (10-73% before mortality), Georges Bank scallops should be conside
red self-sustaining.