PDF(Pubmed)
Abstract：
The aims of this study were to compare male and female sea trout (Salmo trutta) with respect to their hypo-osmoregulatory ability over a simulated migration to seawater and their clinical and physiological response to salmon louse (Lepeophtheirus salmonis) infection in seawater and over a simulated pre-mature return to freshwater. For this purpose, 2-year-old hatchery-reared male and female brown trout (F1 offspring of wild caught anadromous fish) were infected with salmon lice and measured for changes in plasma ions, glucose, lactate and osmolality and relative heart, liver and gonad sizes during a simulated seawater migration and thereafter a premature return to freshwater after 4 weeks in seawater (pre-adult louse). Un-infected trout served as control. Male trout used longer time to develop full hypo-osmoregulatory ability in seawater and showed a stronger response in plasma glucose and lactate following simulated premature return to freshwater, compared to female trout. Response to salmon louse was stronger in female trout, shown by stronger osmotic stress by chalimus (plasma Cl-) and pre-adult louse (plasma osmolality) and elevated relative liver size (hepatosomatic index) by pre-adult louse in female compared to male trout. Moreover, high plasma cortisol in infected female and low plasma cortisol in infected male trout produced a significant treatment-sex interaction on plasma cortisol. Lice infection intensity was initially higher in male (0.18 lice g-1) compared to female trout (0.11 lice g-1) at the chalimus stage, but equal between sexes at the pre-adult stage (male 0.15 and female 0.17 lice g-1). This study showed that female trout were better adapted for changes in water salinity, while male trout were more robust against salmon louse infection. These results suggests that the elevated salmon louse infection pressure generated by salmon farming have strong and unexplored negative effects on wild sea trout populations. Further research on this topic is vital for the conservation of wild sea trout populations.
摘要：
这项研究的目的是比较雄性和雌性海鳟鱼（Salmotrutta）在模拟迁移到海水中的低渗透调节能力以及它们对海水中鲑鱼虱（Lepeophtheirussalmonis）感染的临床和生理反应。模拟过早返回淡水。为此,2岁的孵化场饲养的雄性和雌性棕色鳟鱼（野生捕获的无性系鱼类的F1后代）感染了鲑鱼虱子，并测量了血浆离子的变化，葡萄糖，乳酸和渗透压和相对心脏，在模拟海水迁移期间，肝脏和性腺大小，然后在海水中4周后过早返回淡水（成年前的虱子）。未感染的鳟鱼作为对照。雄性鳟鱼在海水中使用了更长的时间来发展完全的低渗透调节能力，并且在模拟过早返回淡水后对血浆葡萄糖和乳酸表现出更强的反应，与雌性鳟鱼相比。雌性鳟鱼对鲑鱼虱的反应更强，与雄性鳟鱼相比，成年前虱子（血浆Cl-）和成年前虱子（血浆渗透压）的渗透压更强，成年前虱子的相对肝脏大小（肝细胞指数）升高。此外，受感染的雌性鳟鱼中的高血浆皮质醇和受感染的雄性鳟鱼中的低血浆皮质醇对血浆皮质醇产生了显着的治疗-性别相互作用。在chleimus阶段，雄性（0.18虱子g-1）的虱子感染强度最初高于雌性鳟鱼（0.11虱子g-1），但在成年前阶段性别之间相等（男性0.15和女性0.17虱子g-1）。这项研究表明，雌性鳟鱼更好地适应水盐度的变化，而雄性鳟鱼对鲑鱼虱感染更有抵抗力。这些结果表明，鲑鱼养殖产生的鲑鱼虱感染压力升高对野生海鳟鱼种群具有强烈且未探索的负面影响。对该主题的进一步研究对于保护野生海鳟鱼种群至关重要。
