McCormick S D, Haro A, Lerner D T, O'Dea M F, Regish A M
USGS, Conte Anadromous Fish Research Center, Turners Falls, MA 01370, U.S.A.
J Fish Biol. 2014 Oct;85(4):1005-22. doi: 10.1111/jfb.12532.
The timing of downstream migration and detection rates of hatchery-reared Atlantic salmon Salmo salar smolts and stream-reared smolts (stocked 2 years earlier as fry) were examined in the Connecticut River (U.S.A.) using passive integrated transponder (PIT) tags implanted into fish and then detected at a downstream fish bypass collection facility at Turners Falls, MA (river length 192 km). In two successive years, hatchery-reared smolts were released in mid-April and early May at two sites: the West River (river length 241 km) or the Passumpsic (river length 450 km). Hatchery-reared smolts released higher in the catchment arrived 7 to 14 days later and had significantly lower detection rates than smolts stocked lower in the catchment. Hatchery-reared smolts released 3 weeks apart at the same location were detected downstream at similar times, indicating that early-release smolts had a lower average speed after release and longer residence time. The size and gill Na(+) /K(+) -ATPase (NKA) activity of smolts at the time of release were significantly greater for detected fish (those that survived and migrated) than for those that were not detected. Stream-reared pre-smolts (>11·5 cm) from four tributaries (length 261-551 km) were tagged in autumn and detected during smolt migration the following spring. Stream-reared smolts higher in the catchment arrived later and had significantly lower detection rates. The results indicate that both hatchery and stream-reared smolts from the upper catchment will arrive at the mouth of the river later and experience higher overall mortality than fish from lower reaches, and that both size and gill NKA activity are related to survival during downstream migration.
在美国康涅狄格河，通过将被动集成应答器（PIT）标签植入鱼体，然后在马萨诸塞州特纳瀑布的下游鱼类旁路收集设施处进行检测，研究了孵化场养殖的大西洋鲑（Salmo salar）幼鱼和溪流养殖幼鱼（两年前作为鱼苗放养）的下游洄游时间和检测率（河流长度192公里）。在连续两年中，孵化场养殖的幼鱼于4月中旬和5月初在两个地点放流：西河（河流长度241公里）或帕森普西克河（河流长度450公里）。在集水区较高位置放流的孵化场养殖幼鱼7至14天后到达，其检测率显著低于在集水区较低位置放养的幼鱼。在同一地点相隔3周放流的孵化场养殖幼鱼在下游被检测到的时间相似，这表明早期放流的幼鱼放流后平均速度较低且停留时间较长。对于被检测到的鱼（那些存活并洄游的鱼），放流时幼鱼的大小和鳃Na(+) /K(+) -ATP酶（NKA）活性显著大于未被检测到的鱼。来自四条支流（长度261 - 551公里）的溪流养殖前幼鱼（>11.5厘米）在秋季被标记，并在次年春季幼鱼洄游期间进行检测。在集水区较高位置的溪流养殖幼鱼到达时间较晚，检测率显著较低。结果表明，来自集水区上游的孵化场养殖和溪流养殖幼鱼到达河口的时间较晚，总体死亡率高于下游的鱼，并且大小和鳃NKA活性都与下游洄游期间的存活有关。
