Blueback herring is an anadromous fish endemic in the tidal Hudson River Estuary, USA. Twentieth-century improvements to a lock and canal system permitted the species to invade the Hudson's main tributary, the Mohawk River, where it has been recorded since the 1930s. Moving westward over time, individuals were collected in Lake Ontario, approx. 275 km west of the Hudson, in 1997. However, the actual status (resident or marine anadromous) of adults there or in the Mohawk has not been determined. We collected adult blueback herring in the spring 1999 spawning run and analyzed their otoliths' elemental composition with both electron (WDS) and nuclear (2PIXE) microprobes. We measured strontium:calcium ratios along « life-history transects » (WDS) and mapped entire otoliths (2PIXE), providing a detailed time series of data on the Sr:Ca, and thus habitat use history, of the fish. We also analyzed otoliths of Mohawk and Hudson River young-of-year (YOY). The Sr:Ca ratios of Mohawk YOY are slightly but significantly higher than those of Hudson YOY. Life history transects for 51 adults show complex patterns of Sr:Ca, indicating that many of the fish move into salt water at least for brief periods. However, many fish appear to spend extended parts of their post-YOY lives in fresh water, and at least two adults (caught in the Mohawk near Rome, NY) appear never to have changed habitats at all. This is thus the first demonstration of residency in Mohawk River herring.

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Tidal resource assessment for the characterisation of turbine performance or Annual Energy Prediction currently uses the method of bins as recommended by international standards. An alternative method is proposed in this paper and applied to the Sustainable Marine Energy PLAT-I deployment in Connel Sound, Scotland. This method may be suitable for tidal turbines which operate from the surface. Three instrumentation types are used in this work, a bed-mounted Acoustic Doppler Profiler (ADP), and platform-mounted Acoustic Doppler Velocimeter (ADV) and Electromagnetic Current Meter (ECM). By comparing the resource characteristics from these three sources, a comparison of their velocity magnitudes and turbulence characteristics is made, demonstrating the difference between methodologies. It was found that the ADP evaluated using the method of bins produced a more conservative velocity distribution, in comparison to the ADV and ECM. Consequently, a representative AEP showed a difference of 3.8kWh (50% of ADP total) for the month of data collected. When comparing the Turbulence Intensity between devices, the ADP and ECM had similar metrics whilst the ADV had up to 14% higher values. The significance of these differences requires further work comparing them to the SME PLAT-I turbines power output to ascertain which best represents the onset flow experienced by the turbine and if there is a correlation between power performance and turbulence intensity.

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