ASMFC Horseshoe Crab Board Approves Benchmark Stock Assessment for Management Use

Arlington, VA – The 2019 Horseshoe Crab Benchmark Stock Assessment evaluated the stock status of the resource by region, finding populations within the Delaware Bay and Southeast regions remaining consistently neutral and good, respectively, through time.  The Northeast region population has changed from poor to neutral, while the status of the New York region population has trended downward from good, to neutral, and now to poor. The Benchmark Assessment was endorsed by the Peer Review Panel and accepted by the Horseshoe Crab Management Board (Board) for management use.

To date, no overfishing or overfished definitions have been adopted for management use. For the assessment, biological reference points were developed for the Delaware Bay region horseshoe crab population although not endorsed by the Peer Review Panel for use in management. However, given the assessment results of low fishing mortality and relatively high abundance, overfishing and an overfished status are unlikely for female horseshoe crabs in the Delaware Bay region.

In the absence of biological reference points, stock status was based on the percentage of surveys within a region (or coastwide) having a >50% probability of the final year being below the model reference point (referred to as the Autoregressive Integrated Moving Average or ARIMA reference point).  “Poor” status was >66% of surveys meeting this criterion, “Good” status was <33% of surveys, and “Neutral”status was 34 – 65% of surveys.  Based on this criterion, stock status for the Northeast region was neutral; the New York region was poor; the Delaware Bay region was neutral; and the Southeast region was good. Coastwide, abundance has fluctuated through time with many surveys decreasing after 1998 but increasing in recent years. The coastwide status includes surveys from all regions and indicates a neutral trend, likely due to positive and negative trends being combined.

Number of Surveys Below the Index-based 1998 Reference Point in the Terminal (Final) Year of ARIMA Model
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The Board will consider a possible management response to the assessment at its next meeting in August. A more detailed description of the stock assessment results is available on the Commission’s website at The 2019 Horseshoe Crab Benchmark Stock Assessment and Peer Review Report will be available on the Commission website,, on the Horseshoe Crab webpage by mid-May.

For more information, please contact Dr. Mike Schmidtke, Fishery Management Plan Coordinator, at


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