Institute for Marine and Antarctic Studies, University of Tasmania, Hobart, Tasmania, Australia.
PLoS One. 2013 Aug 23;8(8):e74146. doi: 10.1371/journal.pone.0074146. eCollection 2013.
Rock lobster growth is routinely measured for research to optimise management measures such as size limits and quotas. The process of estimating growth is complicated in crustaceans as growth only occurs when the animal moults. As data are typically collected by tag-recapture methods, the timing of moulting events can bias results. For example, if annual moulting events take place within a very short time-at-large after tagging, or if time-at-large is long and no moulting occurs. Classifying data into cases where moulting has / has not occurred during time-at-large can be required and can generally be determined by change in size between release and recapture. However, in old or slow growth individuals the moult increment can be too small to provide surety that moulting has occurred. A method that has been used since the 1970's to determine moulting in rock lobsters involves clipping the distal portion of a pleopod so that any regeneration observed at recapture can be used as evidence of a moult. We examined the use of this method in both tank and long-duration field trials within a marine protected area, which provided access to large animals with smaller growth increments. Our results emphasised that determination of moulting by change in size was unreliable with larger lobsters and that pleopod clipping can assist in identifying moulting events. However, regeneration was an unreliable measure of moulting if clipping occurred less than three months before the moult.
为了优化管理措施（例如大小限制和配额），研究人员通常会定期测量龙虾的生长情况。由于甲壳类动物只有在蜕皮时才会生长，因此估计生长情况的过程较为复杂。由于数据通常是通过标记-重捕方法收集的，因此蜕皮事件的时间可能会影响结果。例如，如果每年的蜕皮事件发生在标记后很短的时间内，或者如果在外时间很长而没有蜕皮。因此，可能需要将外时间内是否发生蜕皮的数据分类，并通常可以通过释放和重捕之间的大小变化来确定。然而，在年老或生长缓慢的个体中，蜕皮增量可能太小，无法确定是否发生了蜕皮。自 20 世纪 70 年代以来，一种用于确定龙虾蜕皮的方法涉及剪断一个腹肢的远端部分，以便在重捕时观察到的任何再生都可以作为蜕皮的证据。我们在海洋保护区内的水箱和长期野外试验中检查了这种方法的使用情况，这些试验为具有较小生长增量的大型动物提供了机会。我们的结果强调，通过大小变化来确定蜕皮的方法在较大的龙虾上不可靠，而剪断腹肢可以帮助识别蜕皮事件。然而，如果在蜕皮前不到三个月进行剪肢，再生则是一种不可靠的蜕皮测量方法。
