The River Herring Assessment Survey was initiated in 2013 in response to the ASMFC’s 2012 River Herring Benchmark Stock Assessment that found both species of river herring to be depleted on a coastwide basis but there was a lack of the quality and quantity of data necessary to make an assessment specific to New Jersey.  In order to fill these data gaps and address research priorities that came out of the stock assessment, Bureau of Marine Fisheries (BMF) staff developed an assessment program to understand spawning adult and young of year population abundance within two New Jersey Rivers.  The Maurice River, and later in 2015 the Great Egg Harbor River, were chosen as representative examples of Delaware Basin and Atlantic Coastal rivers with known populations of river herring. 

Two components of the survey were developed in order to assess two important life history stages of river herring.  River herring are an anadromous fish, meaning they are spawned (born) in freshwater rivers and streams and migrate out to the ocean where they grow to be mature adults which return to the same river or stream they were born in to spawn future generations. The first component of the survey uses anchored gillnets in the Maurice and Great Egg Harbor Rivers which intercept these migrating adult river herring on their way up from the ocean to their historic spawning grounds.  BMF staff deploy these gillnets perpendicular to shoreline from the bow of a small vessel, using bright orange buoys to mark their location.  The nets are left to soak for an hour and a half before they are retrieved and the catch is sorted on board the boat.  BMF staff separate and count all species caught and collect biological data from any target species caught including alewife, bluebacks, and striped bass.  This data includes number caught, fish length, fish sex, spawning maturity stage, and age data.  This component of the survey takes place in the spring from March through May.