Life in the Slow Lane: Ecology and Conservation of Long-Lived Marine Animals

Historical Abundance of Delaware Bay Atlantic Sturgeon and Potential Rate of Recovery

David H. Secor and John R. Waldman

doi: https://doi.org/10.47886/9781888569155.ch16

Abstract. —Atlantic sturgeon Acipenser oxyrinchus oxyrinchus stocks are extremely depleted throughout their range in the United States. We examined two aspects of restoration of Atlantic sturgeon—what level of abundance should be recovered and how long might this level of recovery require? To provide perspective on restoration benchmarks, we estimated historical fishery records for Delaware Bay Atlantic sturgeon. During the period 1880–1900, the Delaware Bay supported the most abundant and commercially important population in the United States. The Leslie depletion method was used to estimate abundance in 1890, a year followed by a 9-yr period of constant depletion. Assumptions of this method were partially met by limited distribution points for the fishery (accuracy of reporting), similarity of fishing practices and fish size during the period of depletion (stable catchability over size-classes) and a 15–20 year lag between depletion of spawning stock and loss of new recruits. Predicted abundance of females, the principal target of the Delaware Bay fishery, was estimated at approximately 1.8 ×10⁵. Based upon a scenario of no directed fishery but continued bycatch of juveniles and constant low annual recruitment of yearlings, restoration to historical levels would require well over a century. Low natural mortality rate in Atlantic sturgeon indicates that additional external sources of mortality, for instance bycatch mortality, can have proportionately large effects on population growth rates.