Graduate School of Fisheries and Environmental Sciences, Nagasaki University, Nagasaki, Japan.
J Fish Biol. 2022 Nov;101(5):1270-1284. doi: 10.1111/jfb.15199. Epub 2022 Sep 7.
Tiger pufferfish Takifugu rubripes (order Tetraodontiformes, family Tetraodontidae) is a highly exploited species and stocks continue to decline, although hatchery-reared juveniles have been released since 1965 for stock enhancement. To determine why the stock has not recovered through hatchery-release practices, this study investigated and compared the population characteristics of wild and hatchery-origin fish. The length-mass relationship showed that hatchery-origin fish were skinnier, with males weighing less than 90% of the mass of wild males of the same length. The hepatosomatic index tended to be lower in hatchery-origin fish. Age was estimated using the otolith-based method, and the estimates were more accurate and precise than those obtained by the conventional vertebra-based method. At the age of 2.9 years, an age at which specimens were the most abundant in catches, hatchery-origin males weighed only 67% of wild males. The maximum observed age was 12 years for wild fish and 5 years for hatchery-origin fish. The instantaneous total mortality rates of hatchery-origin fish were more than twice as high as those of wild fish. In summary, the hatchery-origin fish had poor health status, poor growth and high mortality, and their fitness in natural environments was therefore hypothesized to be low throughout life.
养殖的虎斑河豚（鲀形目，鲀科）已被大量捕捞，种群数量持续下降，尽管自 1965 年以来，为了增加种群数量，已经开始人工养殖幼鱼并放归自然。为了确定为什么通过人工养殖放归的实践并没有使种群得到恢复，本研究调查并比较了野生鱼和养殖鱼的种群特征。体长-体重关系表明，养殖鱼更瘦，同长度的雄性养殖鱼体重比野生鱼轻 90%。养殖鱼的肝体指数往往较低。采用耳石法估计年龄，与传统的基于脊椎骨的方法相比，估计年龄更准确、更精确。在捕捞中最常见的 2.9 岁年龄时，养殖鱼的雄性体重仅为野生雄性的 67%。野生鱼的最大观测年龄为 12 岁，而养殖鱼的最大观测年龄为 5 岁。养殖鱼的瞬时总死亡率是野生鱼的两倍多。总之，养殖鱼的健康状况较差，生长不良，死亡率较高，因此推测其在自然环境中的适应能力较低，一生都处于不利地位。
