Industry-based acoustic survey of Atlantic herring distribution and spawning dynamics in coastal Maine waters

We describe a unique survey method that is able to cover a wide spatial and temporal range at a low cost. We utilised 10 individual small fishing vessels (lobster vessels) as acoustic research platforms to systematically survey a coastal population of Atlantic herring (Clupea harengus) in the Gulf of Maine. We examined 38 transects spanning more than 200 miles of coastline. Due to the low cost of chartering the vessels, the survey was repeated weekly for nine weeks, resulting in over 2300 nautical miles of on-transect data. We calibrated single beam systems using a split beam guiding transducer to increase our confidence in the accuracy of the data and allow inter-ship comparisons. Although only one year of data has been analysed, the large spatial and temporal coverage of this survey provides preliminary information on herring population dynamics including spatial distribution throughout the survey area, timing of spawning and habitat associations of spawning aggregations. This survey will provide the template for longer term monitoring of herring spawning dynamics in Coastal Maine and how this may respond to climate and ocean variability.