In Alabama, Alligator Gar Atractosteus spatula populations have experienced a decline in abundance and due to their limited distribution are classified as a nongame species of moderate conservation concern. Conservation management plans have included creel limits and stocking to augment a diminished population within the lower Alabama River. Our objective was to evaluate gill‐net efficacy on catch and the environmental variables associated with improving broodfish capture rates for hatchery propagation. Broodfish collections were initiated and completed over 75 sample dates between March 2005 and April 2015. Collectors utilized multifilament gill nets consisting of three mesh sizes (101.6, 127.0, and 152.4 mm) and three net lengths (22.9, 30.5, and 61.0 m). Gill nets (n = 569) expended 2,173 h of soak time, resulting in the capture of 101 individuals (TL range = 1,020–2,210 mm). Catch was highest for the smallest mesh size, but net panel length did not influence catch rates. Median fish lengths increased with larger mesh sizes. Catch declined more than sevenfold for net soaks of 1 h or more, and the proportion of successful gill nets declined threefold for longer soak times. Examination of environmental conditions during and prior to the setting of gill nets demonstrated that fish capture success was in part influenced by various aspects of tidal current and water temperature. Catch success was 68% when nets were set at water temperatures of at least 20°C and when at least 50% of net soak time occurred during rising tides. However, success was lower when nets were set at temperatures less than 20°C, capturing Alligator Gar in 44% of all soaks and 37% for those on falling or slack tides. Agencies involved in hatchery propagation programs should continually evaluate field sampling methods, use of collection gear, and environmental conditions to increase broodfish catch rates and improve staff efficacy.

中文翻译：

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阿拉巴马州下莫比尔-天索三角洲的鳄鱼Bro亲鱼评估

在阿拉巴马州，鳄雀鳝Atractosteus铲群体都经历了大量的下降，由于其有限的分布被列为中等保育价值的非游戏类。养护管理计划包括纱架限制和放养，以增加阿拉巴马河下游的人口减少。我们的目标是评估刺网在捕捞上的功效以及与提高亲鱼孵化场繁殖率有关的环境变量。在2005年3月至2015年4月的75个采样日期开始并完成了亲鱼的收集。收集者使用的复丝刺网由三种网目尺寸（101.6、127.0和152.4毫米）和三种网长（22.9、30.5和61.0 m）组成。刺网（n  = 569）花费了2,173 h的浸泡时间，导致捕获了101个人（TL范围= 1,020–2,210 mm）。对于最小的筛孔尺寸，渔获量最高，但净面板长度不会影响渔获率。鱼的中位数随着网眼尺寸的增加而增加。1小时或更长时间的网浸泡，渔获量下降了七倍多，而更长的浸泡时间，成功的刺网的比例下降了三倍。在刺网放置期间和之前进行的环境条件检查表明，鱼类捕获成功的部分原因是潮汐流和水温的各个方面。当网被设置在至少20°C的水温下并且在涨潮期间发生至少50％的净浸泡时间时，捕获成功率为68％。但是，将蚊帐放置在温度低于20°C时，成功率会降低，在所有浸泡中占44％，在落潮或松弛时占37％。孵化场繁殖计划中涉及的机构应不断评估田间采样方法，收集工具的使用以及环境条件，以提高亲鱼的捕获率并提高工作人员的效率。