Blue Catfish Ictalurus furcatus provide a popular sport fishery in Mark Twain Lake, Missouri, but little is known about their population demographics or exploitation by anglers. Our objectives were to (1) determine population demographics of Blue Catfish, (2) determine exploitation of Blue Catfish, and (3) determine whether new harvest regulations would improve the quality (e.g., size structure and abundance) of the fishery in Mark Twain Lake. We sampled Blue Catfish by using jug lines baited with pieces of Gizzard Shad Dorosoma cepedianum , the gear used by the majority of anglers in this reservoir. Blue Catfish grew slowly, reaching a preferred size (762 mm TL) in about 12 years. Annual mortality was estimated at 24.8% using a weighted catch curve. Using reward tags, we estimated exploitation to be between 8% and 12%, and we modeled the effects of 508‐, 610‐, and 660‐mm minimum TL limits on yield and size structure of the Blue Catfish population relative to a baseline of 381 mm TL, the smallest fish usually harvested by anglers. All three length limits increased the proportion of larger fish (≥762 mm TL) in the population without reducing yield, except for slight decreases (6% and 10%) under the 610‐ and 660‐mm limits at the highest modeled natural mortality rate. We recommend the 610‐mm limit instead of the 660‐mm limit because it allows more harvest and higher yields with increases in natural mortality and still doubles the proportion of larger fish relative to the 508‐mm limit.

中文翻译：

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使用渔具评估高度活动的中西部蓝Cat鱼种群的最小长度限制的潜在效益

蓝Cat鱼（Ictalurus furcatus）在密苏里州马克吐温湖（Mark Twain Lake）提供流行的运动渔业，但对其种群人口统计信息或垂钓者的剥削了解甚少。我们的目标是（1）确定蓝Cat鱼的种群统计数据，（2）确定对蓝Cat鱼的开发，以及（3）确定新的捕捞法规是否会改善马克吐温的渔业质量（例如，规模结构和丰度）湖。我们通过使用肫沙德的作品开涮壶线采样蓝鲶鱼Dorosoma cepedianum，大多数钓鱼者在此水库中使用的齿轮。蓝Cat鱼生长缓慢，在大约12年内达到了首选大小（762毫米TL）。使用加权捕获曲线估计年死亡率为24.8％。使用奖励标签，我们估计剥削率在8％和12％之间，并且相对于基线水平，我们模拟了508、610和660毫米最小TL限制对蓝Cat鱼种群产量和大小结构的影响381毫米TL，通常由垂钓者收获的最小鱼类。所有这三个长度限制都增加了种群中较大鱼类（≥762mm TL）的比例，而没有降低产量，但在最高模拟自然死亡率下，在610和660 mm限制下略有下降（分别为6％和10％） 。