Alexandria, VA – The 2015 Atlantic menhaden benchmark assessment indicates the resource is not overfished nor experiencing overfishing relative to the current maximum spawning potential (MSP) based biological reference points. Population fecundity, a measure of reproductive capacity, is estimated to be 71% higher than the target value (100 trillion eggs). Additionally, total fishing mortality is estimated to be 0.27, below both the fishing mortality threshold (2.98) and target (1.03). The Atlantic Menhaden Management Board approved the benchmark stock assessment for management use.
“The assessment findings bring good news regarding the status of the Atlantic menhaden resource and sets the stage for the Board to begin to discuss how it wants to move forward in sustainably managing Atlantic menhaden. This discussion will include Board management objectives that address the needs of the reduction and bait fisheries as well as the ecological services menhaden provides as an important prey species,” stated Board Chair Robert Boyles from South Carolina. “The assessment results are different from prior assessments and this is in large part due to the tremendous efforts of stakeholders, and state and federal scientists to improve upon both the data and modeling approaches used in the assessment. We are grateful for their hard work and dedication in advancing our understanding of the Atlantic menhaden stock status.”
Atlantic menhaden is harvested by both commercial reduction and bait fisheries. From 2010 to 2012, reduction fishery landings averaged 172,600 metric tons and are substantially lower than historical levels. Conversely, total bait landings have been increasing in recent years, averaging about 52,900 metric tons during 2010-2012, with peak landings of about 63,540 metric tons in 2012. In 2013, landings for both fisheries were reduced by 20%, consistent with the requirements of Amendment 2.
Through the consideration of new and existing datasets and the exploration of alternative model configurations, significant changes were made during the 2015 assessment to address the issues identified with the 2010 assessment. Below are a few of the major changes that led to significantly different assessment results.
Using new datasets, maturity at age was corrected, resulting in a higher estimated proportion of mature fish at ages 1, 2, and 3. This higher proportion of mature fish at the earlier ages resulted in a stock that had higher reproductive potential (i.e., increased fecundity) than previously estimated.
Two composite adult indices of relative abundance were created using nine new standardized fishery-independent indices that spanned a much broader spatial scale. This was a significant improvement from the 2010 benchmark assessment that used one Chesapeake Bay fishery-dependent pound net index to characterize adult abundance for the entire stock.
Dome-shaped selectivity for all fishery fleets was used to account for the fact that larger sized individuals were observed in multiple fishery-independent surveys than captured by the bait and reduction fisheries during the entire history of sampling. This ultimately results in more fish at older ages because the larger fish are not being captured by the fisheries.
All these improvements combined led to significantly different assessment results. A more detailed description of the stock assessment results is available on the Commission’s website at http://www.asmfc.org/uploads/file/54d26f852015MenhadenStockAssessmentOverview_Feb2015.pdf.