Assessing Fish Community Structure in a Tidally Dynamic Region

Standard methods for sampling and analyzing finfish communities in a variety of ecosystems are well-established.  These methods are frequently used to document community-level responses to natural or anthropogenic perturbations.  However, people’s interest in new energy-harnessing technologies in more dynamic and less understood environments results in challenges for applying traditional sampling methods; for example, netting under dangerous conditions (e.g. extreme tidal currents) and in habitats not conducive to physical sampling.  Finfish community structure in Cobscook Bay, Maine was studied in connection with development of marine hydrokinetic energy extraction.  Six intertidal and six subtidal sites were sampled in May, June, August, and September in each of three years using seine (n=390), fyke (n=72), benthic trawl (n=112), and pelagic trawl nets (n=111).  Physical netting facilitated the capture of over 60,000 individuals, and was an effective strategy for documenting finfish community structure.  However, it was inefficient in sampling large finfish and those individuals using fast tidal currents (up to 1.8 m/s).  The knowledge of local fishermen and hydroacoustic sampling provided supplemental data that was used to address these data gaps and assist in the interpretation of our results.