Wildlife Conservation Society, Marine Programs, Bronx, NY 10460, USA.
Conserv Biol. 2011 Oct;25(5):945-55. doi: 10.1111/j.1523-1739.2011.01694.x. Epub 2011 Jun 15.
We tested the unsustainable fishing hypothesis that species in assemblages of fish differ in relative abundance as a function of their size, growth rates, vagility, trophic level, and diet by comparing species composition in historical bone middens, modern fisheries, and areas closed to fishing. Historical data came from one of the earliest and most enduring Swahili coastal settlements (approximately AD 750-1400). Modern data came from fisheries near the archeological site and intensively harvested fishing grounds in southern Kenya. The areas we sampled that were closed to fishing (closures) were small (<28 km(2) ) and permanent. The midden data indicated changes in the fish assemblage that are consistent with a weak expansion of fishing intensity and the unsustainable fishing hypothesis. Fishes represented in the early midden assemblages from AD 750 to 950 had longer life spans, older age at maturity, and longer generation times than fish assemblages after AD 950, when the abundance of species with longer maximum body lengths increased. Changes in fish life histories during the historical period were, however, one-third smaller than differences between the historical and modern assemblages. Fishes in the modern assemblage had smaller mean body sizes, higher growth and mortality rates, a higher proportion of microinvertivores, omnivores, and herbivores, and higher rates of food consumption, whereas the historical assemblage had a greater proportion of piscivores and macroinvertivores. Differences in fish life histories between modern closures and modern fishing grounds were also small, but the life histories of fishes in modern closures were more similar to those in the midden before AD 950 because they had longer life spans, older age at maturity, and a higher proportion of piscivores and macroinvertivores than the modern fisheries. Modern closures and historical fish assemblages were considerably different, although both contained species with longer life spans.
我们通过比较历史骨渣、现代渔业和禁渔区的物种组成，检验了不可持续捕捞假说，该假说认为，鱼类群落中的物种丰度会根据其体型、生长率、迁移能力、营养级和食性而有所差异。历史数据来自于东非沿海地区最早和最持久的斯瓦希里人聚居地之一（约公元 750 年至 1400 年）。现代数据来自于考古遗址附近的渔业和肯尼亚南部高度捕捞的渔区。我们抽样的禁渔区（禁渔区）较小（<28 平方公里）且为永久性的。骨渣中的数据表明，鱼类群落发生了变化，这与捕捞强度的微弱扩张和不可持续捕捞假说相一致。公元 750 年至 950 年早期骨渣中出现的鱼类，其寿命更长、成熟年龄更大、世代时间更长，而在公元 950 年之后，体长更长的物种数量增加，这表明鱼类的生活史发生了变化。然而，历史时期鱼类生活史的变化幅度仅为历史和现代组合之间差异的三分之一。现代组合中的鱼类平均体型较小、生长和死亡率较高、微食性动物、杂食动物和草食动物的比例较高、食物消耗率较高，而历史组合中的鱼类则以肉食性鱼类和大型食虫动物为主。现代禁渔区和现代渔业之间的鱼类生活史差异也很小，但现代禁渔区的鱼类生活史与公元 950 年前的骨渣中鱼类生活史更为相似，因为它们的寿命更长、成熟年龄更大、肉食性鱼类和大型食虫动物的比例更高。尽管现代禁渔区和历史鱼类组合都包含寿命较长的物种，但两者之间存在很大的差异。
