Bett Nolan N, Hinch Scott G, Yun Sang-Seon
Department of Forest and Conservation Sciences, University of British Columbia, Vancouver, BC V6T 1Z4, Canada.
Department of Forest and Conservation Sciences, University of British Columbia, Vancouver, BC V6T 1Z4, Canada.
Behav Processes. 2016 Nov;132:76-84. doi: 10.1016/j.beproc.2016.10.001. Epub 2016 Oct 5.
Many fish that are exposed to a threat release disturbance cues, which are chemicals that alert conspecifics to the presence of the threat. The release of disturbance cues has been well demonstrated in various species of laboratory-reared fish. Migratory fish species often exhibit increased cortisol levels and are exposed to numerous stressors during their migrations, which could trigger the release of disturbance cues. We tested the responses of wild migrating sockeye salmon (Oncorhynchus nerka) and pink salmon (O. gorbuscha) to the odours of disturbed and undisturbed conspecifics to determine whether these fish release disturbance cues following exposure to a simulated stressor. Furthermore, we tested the responses of sockeye salmon to water-borne cortisol, following evidence from past studies that this chemical is excreted through the gills of stressed fish, and speculation that endogenous correlates of stress might function as disturbance cues. We found that sockeye salmon avoid the odour of disturbed conspecifics, whereas pink salmon do not. Avoidance occurred in both female and male sockeye salmon, and was associated with an increase in plasma cortisol levels in females, but not in males. We also found no behavioural response to water-borne cortisol, which suggests this chemical does not act as an exogenous disturbance cue in sockeye salmon. Avoidance of disturbed conspecifics could limit exposure to risks during the sockeye salmon spawning migration, but could also delay the rate of migration and thereby accrue reproductive costs.
许多受到威胁的鱼类会释放干扰信号，这些信号是一些化学物质，用于提醒同种个体威胁的存在。干扰信号的释放已在多种实验室养殖的鱼类中得到充分证明。洄游鱼类在洄游过程中往往会表现出血浆皮质醇水平升高，并面临众多应激源，这可能会触发干扰信号的释放。我们测试了野生洄游的红大马哈鱼（Oncorhynchus nerka）和细鳞大麻哈鱼（O. gorbuscha）对受干扰和未受干扰的同种个体气味的反应，以确定这些鱼类在接触模拟应激源后是否会释放干扰信号。此外，鉴于过去的研究表明这种化学物质会通过应激鱼类的鳃排出，并且有人推测应激的内源性相关因素可能起到干扰信号的作用，我们还测试了红大马哈鱼对水中皮质醇的反应。我们发现，红大马哈鱼会避开受干扰的同种个体的气味，而细鳞大麻哈鱼则不会。红大马哈鱼的雌鱼和雄鱼都会出现这种回避行为，并且雌鱼的血浆皮质醇水平会升高，而雄鱼则不会。我们还发现红大马哈鱼对水中皮质醇没有行为反应，这表明这种化学物质在红大马哈鱼中不会作为外源性干扰信号起作用。避开受干扰的同种个体可能会在红大马哈鱼产卵洄游期间限制其面临的风险，但也可能会延迟洄游速度，从而增加繁殖成本。
