Abstract Arapaima are endemic to tropical South America and are among the largest freshwater fishes in the world. Although their populations have been harvested intensely for more than a century they are poorly studied. Here, we estimated for the first time, age, growth, and mortality rates for a Guyanese population of arapaima. Analyses were based on growth ring deposition on scales for 223 individuals (20 208 cm total length, TL), including ages 0 8. Rings on scales were annuli, and the scale radius versus total length relation was cubic. Theoretical maximum TL (∼192 cm) was less than maximum observed length (∼240 cm), but that estimate may have been biased downward by size-selective removal of faster-growing juveniles. Back-calculated TL at first annulus increased 18.6 cm between early and later year-classes, indicating removal of fast-growing juveniles in earlier years. Size-selective harvests may have delayed maturity of average survivors by two years. Comparison of length-mass relationships indicate that, for a given length, Guyanese arapaima will be much heavier than those from central Brazil. Annual total mortality was 62 72 % (ages 2 5 or 6), a rate that precludes notable harvests and that may suggest ongoing illegal harvests.

中文翻译：

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圭亚那巨型巨骨舌鱼的生长和死亡率：对过度开发人口恢复的影响

摘要 巨骨舌鱼是南美洲热带地区的特有种，是世界上最大的淡水鱼类之一。尽管它们的种群已经被大量捕捞了一个多世纪，但对它们的研究却很少。在这里，我们首次估计了圭亚那巨骨舌鱼种群的年龄、生长和死亡率。分析基于 223 只个体（总长度为 20 208 厘米，TL）的鳞片上的年轮沉积，包括 0 至 8 岁。鳞片上的环是环状的，鳞片半径与总长度的关系是立方体。理论最大 TL（~192 厘米）小于最大观察长度（~240 厘米），但该估计可能因尺寸选择性去除生长较快的幼鱼而向下偏倚。倒算第一个环的 TL 在早年级和晚年级之间增加了 18.6 厘米，表明早年去除快速生长的幼鱼。大小选择性的收获可能会将普通幸存者的成熟推迟两年。长度质量关系的比较表明，对于给定的长度，圭亚那的巨骨舌鱼将比来自巴西中部的巨骨舌鱼重得多。年总死亡率为 62 72 %（2 岁 5 岁或 6 岁），这一比率排除了显着收成，并可能表明正在进行的非法收成。