2023 Discard Estimation, Precision, and Sample Size Analyses for 14 Federally Managed Species Groups in the Waters off the Northeastern United States

This report describes the analyses associated with the discard estimation of 14 federally managed fish and invertebrate species groups from July 2021 through June 2022 and the expected at-sea observer coverage for northeastern United States fisheries from April 2023 through March 2024 by using the Standardized Bycatch Reporting Methodology. An estimated 55,824 mt (123,070,619 lb) of federally regulated species were discarded from nonconfidential fleets from July 2021 and June 2022. The top species groups discarded were skates (Rajidae) and sea scallop (Placopecten magellanicus). Across all species groups examined, “no market” was the reason reported for the majority of discards. Analyses also revealed that for fleets with observer coverage, the coverage within a fleet corresponded with the spatial and temporal patterns of fishing activity in terms of kept weight of all species. The discards reported in this document may not necessarily correspond directly with the discard estimates derived for individual stock assessments because of differences in stratification and data. Hence, the discard estimates are not definitive, but they are indicative of where discarding occurred among commercial fleets and for which species groups. An estimated 7,238 sea days are needed to achieve a precision-based performance standard (30% coefficient of variation of the discard estimate) for the 14 fish and invertebrate species groups across 64 fleets. The sea day analyses used a standardized protocol to account for the importance of the discarded species relative to the amount of discards by each fleet and total fishing mortality.

本报告阐述了2021年7月至2022年6月期间，针对14个联邦管辖鱼类和无脊椎动物物种组的丢弃量估算相关分析，以及2023年4月至2024年3月美国东北部渔业采用标准化副渔获物报告方法（Standardized Bycatch Reporting Methodology）的预期海上观察员覆盖情况。据估算，2021年7月至2022年6月期间，非保密作业船队丢弃的受联邦监管的物种总重量达55824公吨（合123070619磅）。丢弃量最高的物种组为鳐科（Rajidae）与巨海扇贝（Placopecten magellanicus）。在所调研的全部物种组中，绝大多数丢弃行为的上报原因为“无市场需求”。分析还显示，对于配备观察员的船队而言，其内部的观察员覆盖率与所有物种的上岸重量所体现的渔业活动时空格局高度契合。由于分层方式与数据存在差异，本报告中上报的丢弃量未必与针对单一种群评估得出的丢弃估算值直接对应。因此，本次丢弃估算并非确定性结果，但可反映商业船队的丢弃发生场景与对应物种组。针对64支船队的14个鱼类和无脊椎动物物种组，若要达成基于精度的绩效标准（丢弃估算值的变异系数为30%），则需累计约7238个海上作业日。本次海上作业日分析采用标准化规程，将各船队的丢弃物种重要性、丢弃总量以及总捕捞死亡率纳入考量。