Spawning time , frequency , and batch fecundity of yellowfin tuna , Thunnus albacares , near Clipperton Atoll in the eastern Pacific Ocean
Spawning time , frequency , and batch fecundity of yellowfin tuna , Thunnus albacares , near Clipperton Atoll in the eastern Pacific Ocean
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东太平洋克利珀顿环礁附近黄鳍金枪鱼Thunnus albacares的产卵时间、频率和批量繁殖力
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发表时间：
2008
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通讯作者：
K. Schaefer
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作者：
K. Schaefer
在东太平洋的Clipperton环礁附近，黄鳍金枪鱼（Thunnus albacares）的产卵发生在2230至0330小时之间，这是基于在一天的不同时间取样的雌性卵巢中存在迁移核和水化期卵母细胞和新的排卵后卵泡。制定了组织学标准来估计排卵后卵泡的年龄，并用于估计产卵频率。睾丸组织的组织学检查提供了精子管结构特征的标准，对估计产卵频率有用。雌鱼产卵间隔平均为1.14天，雄鱼产卵间隔平均为1.22天。平均批次繁殖力为157万个细胞，即每克体重68个卵母细胞。除行为活动外，雌鱼和雄鱼的平均每日产卵成本分别为体重的0.97%和0.28%。1995年7月14日接受稿件。渔业公报94:98-112（1996）。黄鳍金枪鱼（Thunnus albacares）的生殖生物学知识对于全面了解该物种的种群动态至关重要。以前对黄鳍金枪鱼生殖生物学的研究涉及产卵分布、性别比例、成熟长度和繁殖力等主题（Wild, 1994）。然而，关于雄性或雌性黄鳍金枪鱼的成熟和产卵的基本信息以前还没有阐明。了解排卵后卵巢卵泡的外观和寿命对于估计产卵频率是必要的。含有排卵后卵泡的卵巢的频率已被用来估计一些鲭鱼的产卵频率，包括鲣鱼、大腹鱼（Hunter等）。, 1986);黄鳍金枪鱼（McPherson, 1991）；大眼金枪鱼（Nikaido et aI）。, 1991);和鲐鱼（Scomberjaponicus）（迪克森等）。, 1992)。然而，排卵后卵泡的年龄和寿命仅测定了圈养的鲣鱼、金枪鱼和鲐鱼（Hunter et aI）。, 1986;迪克森等人。, 1992)。使用组织学方法通常比性器官指数或卵母细胞直径测量提供更精确的标准来评估个体的生殖状态（Hunter and Macewicz, 1985; West, 1990）。尽管硬骨鱼睾丸的组织学检查已经描述了季节性周期的结构变化（Grier, 1981），并用于估计成熟时的长度和确定产卵季节，但还没有关于硬骨鱼睾丸变化与节律性产卵活动的关系的研究。关于金枪鱼睾丸组织学的信息很少，因为大多数研究人员都满足于“大体形态或性器官指标”来衡量雄性的生殖活动。尽管对长鳍金枪鱼的睾丸进行了组织学检查，但长鳍金枪鱼（Thunnus alalunga, Ratty et aI.）大眼金枪鱼，Thunnus obesus (Nikaido et aI。（1991），提供了雄性金枪鱼精子发生的某些方面和性成熟特征的描述，但没有描述金枪鱼睾丸的组织学特征，这些特征可以用来确定雄性金枪鱼何时产卵，从而有助于估计雄性金枪鱼的产卵频率和繁殖努力。黄鳍金枪鱼，像许多亚热带和热带远洋鱼类一样，不断产生一批又一批的水合卵母细胞（Hunter等）。, 1985)。它们的年繁殖能力是不确定的，在任何给定的时间都超过卵巢内的卵母细胞存量。年轮：产卵时间。频率。黄鳍金枪鱼99 14和SI雌（n-33） 1986•雄（n-26） 12
-Spawning of yellowfin tuna, Thunnus albacares, around Clipperton Atoll, in the eastern Pacific Ocean, occurred between 2230 and 0330 h on the basis of the presence of migratory-nucleus and hydrated-stage oocytes and new postovulatory follicles in ovaries offemales sampled at different times of the day. Histological criteria were developed to estimate the ages of the postovulatory follicles and used to estimate spawning frequency. Histological examinations oftesticular tissues provided criteria on the structural characteristics of the sperm duct useful for estimation of spawning frequency. The mean interval between spawnings was 1.14 days for females and 1.22 days for males. The average batch fecundity was 1.57 million 00cytes, or 68 oocytes per gram of body weight. The average daily cost of spawning, excluding behavioral activities, is estimated to be 0.97% and 0.28% of the body weight per day for females and males, respectively. Manuscript accepted 14 July 1995. Fishery Bulletin 94:98-112 (1996). Knowledge of the reproductive biology of yellowfin tuna, Thunnus albacares, is essential for a comprehensive understanding ofthe population dynamics ofthis species. Previous investigations on the reproductive biology of yellowfin tuna have addressed the topics ofspawning distribution, sex ratios, length at maturity, and fecundity (Wild, 1994). However, fundamental information on maturation and spawning has not previously been elucidated for either male or female yellowfin tuna. Knowledge ofthe appearance and longevity of postovulatory follicles in ovaries after spawning is necessary for estimating spawning frequency. The frequency of ovaries containing postovulatory follicles has been used to estimate spawning frequency in some scombroid fishes, including skipjack tuna, Katsuwonus pelamis (Hunter et aI., 1986); yellowfin tuna (McPherson, 1991); bigeye tuna, Thunnus obesus (Nikaido et aI., 1991); and chub mackerel, Scomberjaponicus (Dickerson et aI., 1992). However, the age and longevity of postovulatory follicles have been determined only for skipjack tuna and chub mackerel held in captivity (Hunter et aI., 1986; Dickerson et aI., 1992). The use of histological methods generally provides more precise criteria than do gonosomatic indices or oocyte diameter measurements for assessing reproductive status ofindividuals (Hunter and Macewicz, 1985; West, 1990). Although structural changes over seasonal cycles have been described from histological examinations of teleost testes (Grier, 1981) and used to estimate length at maturity and define spawning seasons, there have been no investigations of diel testicular changes in relation to rhythmic spawning activity. Information on testicular histology in tunas is scarce because most researchers have been satisfied with" gross morphological or gonosomatic indices to measure the reproductive activity of males. Although histological examinations of the testes from albacore tuna, Thunnus alalunga (Ratty et aI., 1990), and bigeye tuna, Thunnus obesus (Nikaido et aI., 1991), have provided descriptions of some aspects of spermatogenesis and characteristics of sexual maturity in male tunas, there have been no descriptions of histological characteristics of tuna testes which can be used to determine when a male has spawned and which would thus be useful for estimating the spawning frequency and reproductive effort of males. Yellowfin tuna, like many subtropical and tropical pelagic fishes, continuously produce batches of hydrated oocytes (Hunter et aI., 1985). Their annual fecundity is indeterminate and exceeds the standing stock ofoocytes within the ovaries at any given time. Annual Schaefer: Spawning time. frequency. and batch fecundity of Thunnus albacares 99 14 &'SI Females (n-33) 1986 • Males (n-26) 12