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Stock Status

In 2012, the Atlantic States Marine Fisheries Commission (ASMFC) completed its benchmark stock assessment for river herring. It found  stocks on the U.S. Atlantic coast are depleted to near historic lows. The “depleted” determination was used instead of “overfished” and “overfishing” because many factors, not just directed and incidental fishing, are contributing to the declining abundance of river herring. In addition to reducing harvest, recovery of river herring will need to address issues such as fish passage, predation, water quality, and climate change.

The assessment  looked at the available data for 52 stocks of alewife and blueback herring, and determined, where possible, stock status relative to historic levels. It found that 23 stocks were depleted, one stock was increasing, and were unable to determine the status for 28 stocks due to lack of data. Trends over the last ten years of data showed two stocks increasing, six were stable, and four were decreasing, with the trend being unknown for the remaining rivers from Maine through South Carolina. Trends were assessed by identifying patterns in the available data, where data was insufficient conduct a model-based assessment. Because the river herring assessment is data-poor, it could not determine true estimates of abundance or fishing mortality.

Get a historical perspective of river herring commercial landings.

During the National Marine Fisheries Services' (NMFS) review of the status of the species, in order to assess the risk of extinction for alewife and blueback herring, to inform the listing determination, rangewide trends in the relative abundance of alewife and blueback herring were assessed for each species, as well as for each species-specific stock complex (see Northeast Fisheries Science Center's (NEFSC) Trend Analysis). For alewife, the stock complexes include Canada, Northern New England, Southern New England, and the mid-Atlantic. For blueback herring, the stock complexes are Canada, Northern New England, Southern New England, Mid-Atlantic, and Southern. The baseline for the overall risk assessment assumed that there has already been a significant decline in abundance in both species due to a reduction in carrying capacity and overfishing as indicated in various publications, as well as other threats. The modeling generated a population growth rate for each species and stock complex. The data used to inform the modeling for the coast-wide trend were from specific NEFSC trawl surveys. Stock-specific time series of alewife and blueback herring relative abundance were obtained from the ASMFC stock assessment and Canada's Department of Fisheries and Oceans. Relative abundance of a stock was considered to be significantly increasing or decreasing if the 95% confidence intervals of the population growth rate did not include zero. In contrast, if the 95% confidence intervals included zero, the population was considered to be stable because the increasing or decreasing trend in abundance was not significant. For alewife, modeling results showed an increasing trend for coastwide and Canada stock, and stable for the Northern New England, Southern New England, and Mid-Atlantic. For blueback herring, modeling results showed a stable trend coastwide, and in the Northern New England, Southern New England and Southern Atlantic stocks, and a decreasing trend in the Mid-Atlantic. No data was available for the Canada stock of blueback herring.

The river herring Technical Expert Working Group (TEWG) Stock Status Subgroup  has considered issues specific to appropriate methodologies to quantitatively assess river herring populations rangewide (e.g., consider data poor approaches, identify data needs). Additional information on these discussions, including identified research needs to inform the topic and ongoing efforts can be found at: