McBride Richard S, Thurman Paul E
Florida Marine Research Institute, Florida Fish and Wildlife Conservation Commission, 100 8th Avenue SE, St. Petersburg, Florida 33701-5095, USA.
Biol Bull. 2003 Feb;204(1):57-67. doi: 10.2307/1543496.
Analyses of life-history data show that both the size-specific batch fecundities and the age-specific spawning frequencies differ for two halfbeak species, Hemiramphus brasiliensis, the ballyhoo, and H. balao, the balao. Halfbeak ages were determined from sectioned otoliths; histological data was used to describe oocyte development and estimate spawning frequency; and batch fecundity was measured from counts of whole oocytes in final maturation. Hemiramphus brasiliensis lived longer (4 versus 2 years) and had a higher survival rate (14.9% versus 7.5% annually) than H. balao did. Of the two species the larger and longer-lived congener, H. brasiliensis, reached sexual maturity at a larger size (fork length 198 versus 160 mm). The spawning period of age-0 females was strongly related to season, whereas spawning by older females occurred throughout the year. Reproduction by both species peaked during late spring or early summer, and all mature females were spawning daily during April (H. brasiliensis) or June (H. balao). This is the first demonstration of iteroparity for the family Hemiramphidae. H. brasiliensis had a lower batch fecundity (about 1164 versus 3743 hydrated oocytes for a 100-g female) than H. balao did. Such low batch fecundities are typical of the order Beloniformes, but quite different from those of other fishes that live in association with coral reef habitats. H. balao's higher batch fecundity is consistent with the life-history theory that predicts higher numbers of eggs for shorter-lived species; this is possible because H. balao produces smaller hydrated oocytes than H. brasiliensis (modal diameter about 1.6 versus 2.4 mm). The high spawning frequency of Hemiramphus species compensates for their low batch fecundity. The annual fecundity of both species is similar to that of other reef fish species, after adjusting for body size and spawning frequency. The lifetime fecundity of H. balao was very similar to that of H. brasiliensis, after accounting for the differences in survival for each species. This suggests a fine tuning of different reproductive traits over the entire life cycle that results in roughly equivalent lifetime fecundity for both species.
对生活史数据的分析表明，巴西下鱵鱼（Hemiramphus brasiliensis，也称针嘴鱼）和巴拉奥下鱵鱼（H. balao）这两种下鱵鱼的特定体长批量繁殖力和特定年龄产卵频率均有所不同。下鱵鱼的年龄通过切割耳石来确定；组织学数据用于描述卵母细胞发育并估计产卵频率；批量繁殖力通过对最终成熟阶段的完整卵母细胞计数来测量。巴西下鱵鱼的寿命更长（4年对2年），年存活率也更高（每年14.9%对7.5%）。在这两个物种中，体型更大、寿命更长的巴西下鱵鱼达到性成熟时的体型更大（叉长198毫米对160毫米）。0龄雌鱼的产卵期与季节密切相关，而老龄雌鱼全年均可产卵。两个物种的繁殖高峰期均出现在春末或夏初，在4月（巴西下鱵鱼）或6月（巴拉奥下鱵鱼）时，所有成熟雌鱼每天都在产卵。这是鱵科鱼类中首次证明多次繁殖现象。巴西下鱵鱼的批量繁殖力较低（对于100克重的雌鱼，约有1164个对3743个水化卵母细胞）。这种低批量繁殖力是颌针鱼目的典型特征，但与生活在珊瑚礁栖息地的其他鱼类有很大不同。巴拉奥下鱵鱼较高的批量繁殖力与生活史理论相符，该理论预测寿命较短的物种会产出更多卵；这是可能的，因为巴拉奥下鱵鱼产生的水化卵母细胞比巴西下鱵鱼小（平均直径约1.6毫米对2.4毫米）。下鱵鱼物种的高产卵频率弥补了它们低批量繁殖力的不足。在调整了体型和产卵频率后，两个物种的年繁殖力与其他珊瑚礁鱼类物种相似。在考虑了每个物种存活率的差异后，巴拉奥下鱵鱼的终生繁殖力与巴西下鱵鱼非常相似。这表明在整个生命周期中，不同繁殖特征进行了精细调整，使得两个物种的终生繁殖力大致相当。
