Delgado Gabriel A, Glazer Robert A, Stewart Nicola J
Florida Fish and Wildlife Conservation Commission, Florida Marine Research Institute, 2796 Overseas Highway, Suite 119, Marathon, Florida 33050, USA.
Biol Bull. 2002 Aug;203(1):112-20. doi: 10.2307/1543463.
Florida queen conch stocks once supported a significant fishery, but overfishing prompted the state of Florida to institute a harvest moratorium in 1985. Despite the closure of the fishery, the queen conch population has been slow to recover. One method used in the efforts to restore the Florida conch population has been to release hatchery-reared juvenile conch into the wild; however, suboptimal predator avoidance responses and lighter shell weights relative to their wild counterparts have been implicated in the high mortality rates of released hatchery juveniles. We conducted a series of experiments in which hatchery-reared juvenile conch were exposed to a predator, the spiny lobster (Panulirus argus), to determine whether they could develop behavioral and morphological characteristics that would improve survival. Experiments were conducted in tanks with a calcareous sand substrate to simulate a natural environment. Conditioned conch were exposed to caged lobsters while conch in the control tanks were exposed to empty cages. Conditioned conch moved significantly less and buried themselves more frequently than the naive control conch. Morphometric data indicated that the conditioned conch grew at a significantly slower rate than the naive conch, but the shell weights of the two groups were not significantly different. This implies that the conditioned conch had thicker or denser shells than the control group. As a result, the conditioned conch had significantly higher survival than naive conch in a subsequent predation experiment in which a lobster was allowed to roam free in each tank for 24 hours. In the future, the conditioning protocols documented in this study will be used to increase the survival of hatchery-reared conch in the wild.
佛罗里达女王凤凰螺种群曾经支撑起一个规模可观的渔业，但过度捕捞促使佛罗里达州在1985年实施了捕捞禁令。尽管渔业关闭了，女王凤凰螺种群的恢复却一直很缓慢。为恢复佛罗里达凤凰螺种群所采取的一种方法是将孵化场培育的幼年凤凰螺放归野外；然而，相对于野生同类，放归的孵化场幼年凤凰螺在躲避捕食者方面反应欠佳，且壳重较轻，这被认为是导致其高死亡率的原因。我们进行了一系列实验，让孵化场培育的幼年凤凰螺接触一种捕食者——多棘龙虾（Panulirus argus），以确定它们是否能形成有助于提高生存几率的行为和形态特征。实验在装有钙质沙质底质的水箱中进行，以模拟自然环境。对经过条件训练的凤凰螺，让它们接触关在笼子里的龙虾，而对照组水箱中的凤凰螺则接触空笼子。与未经训练的对照凤凰螺相比，经过条件训练的凤凰螺移动明显更少，且更频繁地将自己埋起来。形态测量数据表明，经过条件训练的凤凰螺生长速度明显慢于未经训练的凤凰螺，但两组的壳重没有显著差异。这意味着经过条件训练的凤凰螺的壳比对照组的更厚或更致密。结果，在随后的捕食实验中，当允许一只龙虾在每个水箱中自由活动24小时时，经过条件训练的凤凰螺的存活率明显高于未经训练的凤凰螺。未来，本研究中记录的条件训练方案将用于提高孵化场培育的凤凰螺在野外的存活率。
