Department of Biology, University of Minnesota Duluth, Duluth, Minnesota, USA.
Department of Biological Sciences, North Dakota State University, Fargo, North Dakota, USA.
J Fish Biol. 2022 Nov;101(5):1301-1311. doi: 10.1111/jfb.15201. Epub 2022 Sep 8.
The bowfin Amia calva is an amiid (Amiiformes) relict native to North America. It is the last surviving member of the Halecomorphi, a group of fishes that evolved more than 250 million years ago. Despite the phylogenetic significance of the amiids in vertebrate evolution, little has been published about their age and growth. Recreational bowfin harvest is currently unregulated throughout most of the USA, yet new recreational fisheries are emerging. As such, bowfin are increasingly harvested by sport bowfishing without limit, in addition to their growing commercial harvest for caviar. From 2017 to 2021 we studied a total of 81 bowfin from 11 populations across the east-west gradient of Minnesota within a narrow latitudinal margin (<50 km) of the 46th parallel north. We compared the allometry and translucence of bowfin asteriscus, lapillus and sagittal otoliths and found the lapillus otoliths provide consistent readability for age estimation despite being the smallest of the set. Size-at-age data derived from otoliths indicated that bowfin are sexually dimorphic in asymptotic length and may live up to 33 years, which is 15 years longer than previously estimated in wild populations, but comparable to what has been reported in captivity. Overall, 28% of the otolith-aged fish were estimated as older than the previously reported maximum age for wild bowfin populations. Our findings suggest that the bowfin life history may exhibit slower growth, greater longevity, and more variable recruitment than previously recognized, which sets the stage for more otolith-derived population demographics across their range and age validation study. Our results have direct implications for conservation of bowfin, especially amidst the increasing rates of exploitation during the bowfishing era.
弓鳍鱼 Amia calva 是一种原产于北美的 amiid（Amiiformes）鱼类。它是 Halecomorphi 的唯一现存成员，Halecomorphi 是一组起源于 2.5 亿多年前的鱼类。尽管 amiids 在脊椎动物进化中的系统发生意义重大，但关于它们的年龄和生长情况的研究却很少。在美国的大部分地区，娱乐性的弓鳍鱼捕捞目前不受监管，但新的娱乐性渔业正在出现。因此，除了不断增长的鱼子酱商业捕捞外，弓鳍鱼还越来越多地被运动射鱼者无限制地捕捞。从 2017 年到 2021 年，我们研究了来自明尼苏达州东西梯度的 11 个种群的总共 81 条弓鳍鱼，这些种群位于北纬 46 度线以北的一个狭窄纬度范围内（<50km）。我们比较了弓鳍鱼的星状突、腹侧突和矢耳石的生长率和透明度，发现尽管腹侧突耳石是最小的一组，但它提供了一致的年龄估计可读性。耳石大小与年龄的数据表明，弓鳍鱼在渐近长度上存在性别二态性，可能活到 33 岁，这比以前在野生种群中估计的寿命长 15 年，但与圈养中的报告相当。总体而言，28%的耳石年龄鱼被估计为比以前报道的野生弓鳍鱼种群的最大年龄还要大。我们的研究结果表明，与以前认识到的相比，弓鳍鱼的生活史可能表现出生长缓慢、寿命更长和更可变的繁殖，这为在其分布范围内进行更多的耳石衍生种群动态学研究和年龄验证研究奠定了基础。我们的研究结果对弓鳍鱼的保护具有直接意义，尤其是在射鱼时代日益增加的捕捞率的情况下。
