This campaign follows five years of studies of the hydrodynamics of the Saint-Pierre and Miquelon archipelago (SPM), which revealed that in this region of the northwest Atlantic, the tidal current regime is highly specific and quite remarkable. Sea level oscillations are predominantly semi-diurnal, but the associated currents are both semi-diurnal and diurnal, with the latter component often dominant. From spring to autumn, the water column stratifies, as SPM is located at an average latitude of 47°N, with surface temperatures that can reach 18°C, while bottom waters remain cold at 2-3°C on average. Numerous observations since the early 2010s have shown that diurnal oscillations in bottom temperatures have exceptional amplitudes at depths of 10 to 60 m, reaching up to ten degrees during the day.

The SPM2017 campaign took place in this unique environment. Thanks to the use of an oceanographic vessel, several disciplines were able to participate in the description of the coastal environment in a region highly constrained by physics. The SPM2017 campaign can be divided into different sections:

- A section dedicated to hydrodynamics (SPM2017_Phys), aimed at understanding the archipelago's highly specific current regimes and then modeling them. These observations have led to a better understanding of the extreme variability of bottom water temperatures, with the potential for short-term prediction.

- A fisheries component (SPM2017_Hals) aimed at updating knowledge of the scallop stock in the French-Canadian zone known as the ¿Boite à pétoncles¿. In addition, an assessment of the sea cucumber resource was carried out in the southern part of French waters to provide the expertise needed to manage this newly exploited resource.

- A section dedicated to the study of bivalves (SPM_2017Biv): SPM is rich in different species, all of which record variations in environmental conditions through the composition of their shells. This work will not only provide a better understanding of bivalves' reactions to sudden temperature variations, but will also enable us to reconstruct past time series of changes in environmental variables over periods ranging from a day (or even less) to several decades, depending on the species.

- A phytoplankton component (SPM_Phyt), focusing on phycotoxin-producing species, which are very poorly known in this region. The few samples already taken have revealed a very rich floristic composition in this region, where many plankton species are still unknown and could be described. Samples will be taken from various bodies of water to provide the first over