Developing a fine scale system to address river herring (Alosa pseudoharengus, A. aestivalis) and American shad (A. sapidissima) bycatch in the U.S. Northwest Atlantic mid-water trawl fishery

Managers of the Atlantic herring (Clupea harengus) and mackerel (Scomber Scombrus) fisheries have a goal of reducing river herring (Alosa pseudoharengus, Alosa aestivalis) bycatch. Regulations being considered include temporarily closing 30 nm × 30 nm river herring “hotspots” or enacting these measures if a threshold amount of river herring is observed. These closures could be effective at reducing river herring bycatch, but would result in significant economic cost. The uncertainty of the effect of bycatch on river herring populations coupled with potential economic losses due to closed areas suggests a finer scale, voluntary method may be more appropriate. A collaboration between the Sustainable Fisheries Coalition, the Massachusetts Division of Marine Fisheries, and the University of Massachusetts Dartmouth School of Marine Science and Technology seeks to address this issue by implementing near real-time bycatch information systems for this fishery. The first system was implemented during the 2011 winter mid-water trawl fishery (January through March) over an approximate 60 nm × 70 nm area off the coast of New Jersey. Fifty percent of vessels landing in Massachusetts were sampled during this time period. Bycatch information from these vessels was accessed and shared with participating captains using a coded grid of smaller cells approximately 5 nm × 8 nm (10′ longitude × 5′ latitude). Industry collaboration and the appearance of small scale spatial and temporal patterns during the 2011 winter fishery suggests this is a plausible approach to reduce river herring and American shad (Alosa sapidissima) bycatch. The comparison of the results of this study to potential management actions displays both advantages and disadvantages of using a larger spatial scale to reduce bycatch while maintaining an active fishery.

► We test if a voluntary system to avoid bycatch can be used in this fishery.
► We compare different spatial scales to address the bycatch issue.
► Vessels moved from high bycatch areas to low bycatch areas on a fine spatial scale.
► Larger scale closures may eliminate more bycatch but at a higher economic cost.
► Avoidance system could be used as a tool to keep bycatch below a regulatory limit.