Marquardt Alexandria R, Southworth Melissa, Scheld Andrew M, Button Andrew, Mann Roger
Virginia Institute of Marine Science, William & Mary, P.O. Box 1346, Gloucester Point, VA, 23062, USA.
Virginia Institute of Marine Science, William & Mary, P.O. Box 1346, Gloucester Point, VA, 23062, USA.
J Environ Manage. 2025 Feb;375:124179. doi: 10.1016/j.jenvman.2025.124179. Epub 2025 Jan 24.
Coastal ecosystems are degraded worldwide and oyster reefs are among the most threatened coastal habitats. Oysters are a critical ecosystem engineer and valuable fishery species, thus effective management strategies must balance tradeoffs between protecting reef ecosystems and continued human use. Management practices for oysters commonly incorporate shell replenishment (provisioning hard substrates to increase reef relief) and spatial management (rotational harvest areas or sanctuaries); however, the impact of these practices on reef dynamics and fisheries outcomes are poorly understood, particularly on harvested reefs. This project examines the efficacy of shell replenishment and spatial management practices on public fishing grounds by analyzing long term datasets available for the Rappahannock River in the Chesapeake Bay, USA. Using generalized linear mixed effects models, we examine how oyster reef metrics (brown shell substrate L m, recruit density m, market density m) and fisheries efficiency (meeting daily bushel harvest limit or not) respond to management actions. Our results indicate that a 3 y rotation maintains the underlying reef structure, enhances recruitment, and increases market sized oyster density by 1.23 oysters m on average. Sanctuaries and harvested reefs had comparable brown shell and recruit density; however, sanctuaries had higher market oyster density on average. Shell replenishment practices directly enhanced harvester efficiency, particularly in harvest areas with poor reef condition. Our results indicate that low levels of replenishment (∼1000 bushels acre) provide substantial benefits to oyster reefs and the fishery. This study is the first to evaluate the marginal benefits of replenishment activities for biological and fisheries outcomes, and a novel, real world assessment for oyster restoration practices on public fishing grounds. Cumulatively, our findings show that spatial management and replenishment practices enhance oyster reefs in temperate estuaries and offers a framework applicable to other degraded ecosystems worldwide.
全球沿海生态系统均遭退化，牡蛎礁是受威胁最严重的沿海栖息地之一。牡蛎是重要的生态系统工程师和珍贵的渔业物种，因此有效的管理策略必须在保护礁生态系统与人类持续利用之间权衡利弊。牡蛎的管理措施通常包括贝壳补充（提供硬质基质以增加礁体起伏）和空间管理（轮作捕捞区域或保护区）；然而，这些措施对礁体动态和渔业成果的影响却鲜为人知，尤其是对已捕捞的礁体。本项目通过分析美国切萨皮克湾拉帕汉诺克河的长期数据集，研究了公共渔场贝壳补充和空间管理措施的效果。我们使用广义线性混合效应模型，研究牡蛎礁指标（棕色贝壳基质L/m、补充群体密度/m、上市规格密度/m）和渔业效率（是否达到每日蒲式耳捕捞限额）如何对管理行动做出反应。我们的结果表明，3年一轮作可维持礁体的基础结构，促进补充群体的生长，并使上市规格牡蛎的密度平均每平方米增加1.23只。保护区和已捕捞的礁体具有相当的棕色贝壳和补充群体密度；然而，保护区的上市牡蛎密度平均更高。贝壳补充措施直接提高了捕捞效率，尤其是在礁体状况较差的捕捞区域。我们的结果表明，低水平的补充（约1000蒲式耳/英亩）能为牡蛎礁和渔业带来显著益处。本研究首次评估了补充活动对生物和渔业成果的边际效益，是对公共渔场牡蛎恢复措施的一项新颖的现实评估。总体而言，我们的研究结果表明，空间管理和补充措施可增强温带河口的牡蛎礁，并提供了一个适用于全球其他退化生态系统的框架。
