Modelling the effects of currents and migratory behaviours on the dispersal of Atlantic salmon (Salmo salar) post-smolts in a coastal embayment

Abstract

The post-smolt phase is considered a critical period for Atlantic salmon (Salmo salar). Hence, identifying migration routes used by post-smolts is needed to protect the habitats they require to successfully complete their life cycle. We used a bio-physical model coupled with output from a water circulation model (FVCOM) to simulate dispersal of Atlantic salmon post-smolts in a semi-enclosed bay: Passamaquoddy Bay, New Brunswick, Canada. The model was run with nine post-smolt behaviours and six swimming speeds, and then tested against acoustic telemetry data. While no modelled behaviour entirely captured observed salmon migration routes, we identified some behaviours that could allow salmon to successfully leave the bay and resulted in predictions that matched observations reasonably well (e.g., swimming southwest, negative or tide-varying rheotaxis). We could also rule out several behaviours as unlikely to be used by Atlantic salmon post-smolts in this area (e.g., passive dispersal, orienting based on salinity or temperature, positive rheotaxis). Hence, with suitable behaviours and models, this approach can provide estimates of the essential habitats and migration routes of wild post-smolts.

Modelling the dispersion of infectious salmon anemia virus from Atlantic salmon farms in the Quoddy Region of New Brunswick, Canada and Maine, USA

“…Thirteen farms representing a range of hydrographic conditions and connectivity were included in this study, and a simulation was completed independently with each of them as the index farm. All these farms are located in the migration path of Atlantic salmon post-smolts in the region (Lacroix et al 2004;Quinn et al 2022).…”

“…A coastal ocean circulation model based on the unstructured-grid Finite Volume Community Ocean Model (FVCOM, Chen et al 2012) has been implemented to simulate the dynamic physical oceanographic environment in Passamaquoddy Bay and adjacent areas (i.e., the Quoddy Region). A detailed description of the model can be found in Quinn et al (2022), with some basic configurations summarized below. The FVCOM domain covers the Scotian Shelf, Gulf of Maine, and Bay of Fundy, including waters in and just outside of Passamaquoddy Bay (Fig.…”

“…Comparisons of the physical oceanographic model's predictions were made against sea surface height measured from a tide gauge to the south of Passamaquoddy Bay and vertical temperature/salinity profile data from station Prince 7 of the Atlantic Zone Monitoring Program survey (https://www.df o-mpo.gc.ca/science/data-donnees/azmp-pmza/index-eng), as well as overall regional patterns in surface residual currents, salinity, and temperature (Quinn et al 2022). Further, the particle tracking model within Passamaquoddy Bay was tested against trajectories of GPS-equipped surface drifters (Quinn et al 2022 In this study, hourly FVCOM outputs for the period between 1 May to 1 July 2018 were retrieved for analysis, as May-June is the period when wild post-smolt conspecifics are more likely to swim near salmon aquaculture sites in this area (Lacroix et al 2004). Sur-…”

Fjord circulation permits a persistent subsurface water mass in a long, deep mid-latitude inlet

“…This Lagrangian model has been used for many applications related to tracking of pathogens, viruses, salmon post-smolts, etc. (e.g., Foreman et al, 2015;Quinn et al, 2022;DFO, 2022). Here, we followed the application of PTrack described in a study of the hydrodynamic connectivity between marine finfish aquaculture facilities in BC (DFO, 2022), using a time step of 10 s and outputting particle locations every hour.…”

The Impact of Tides and Monsoons on Tritium Migration and Diffusion in Coastal Harbours: A Simulation Study in Lianyungang Haizhou Bay, China

“…In another study [24], a high-resolution regional model (Nucleus for European Modelling of the Ocean) simulated the distribution of tritium in the Mediterranean Sea. In a different study [25], a combined biophysical and water cycle model simulated the dispersion of Atlantic salmon in a semi-enclosed bay. In another study [26], the combination of a hydrodynamic model and evaporation-atmosphere transport model was constructed, which assessed the average tritium release from the coast into the English Channel.…”