High predation of marine turtle hatchlings near a coastal jetty, Thevenard Island, Western Australia

We used passive acoustic telemetry to examine the effects of a jetty and artificial light on the rates of predation of flatback turtle (Natator depressus) hatchlings as they disperse through nearshore waters. A total of 61 hatchlings were released, 30 of which were released when artificial lights were present on the jetty. Predation rates were high, irrespective of the presence or absence of artificial light. Around 72% of the tagged hatchlings were predated before they could transit the nearshore. Evidence for predation was provided by tag detachment, likely due to prey handling by a predator or the extensive movement of the tags within the receiver array suggesting that the tag (and hatchling) was inside the stomach of a predator. This allowed us to track the movement of the hatchling predators. We found that 70% of the fish predators that consumed tags used the jetty as a refuge during the day and moved along nearshore waters at night. Our study shows how industrial development and the creation of nearshore structures such as jetties may have unintended consequences and pose a significant threat to populations of vulnerable species.

本研究采用被动声学遥测（passive acoustic telemetry）技术，探究突堤与人工光照对平背龟（Natator depressus）幼体在近海水域扩散过程中的被捕食率影响。研究共放归61只平背龟幼体，其中30只的放归时段内突堤上设有人工光照。结果显示，无论是否存在人工光照，幼体被捕食率均处于较高水平；约72%的标记（tag）幼体在完成近海水域洄游前即被捕食。捕食证据可通过标记脱落得到证实：其成因可能为捕食者处理猎物时造成标记脱落，或是标记在水声接收阵列（receiver array）内的大范围移动——这表明标记（连同幼龟）已进入捕食者体内。这一发现使得我们得以追踪捕食幼龟的捕食者的移动轨迹。研究发现，70%的捕食过标记幼龟的鱼类捕食者会在日间以突堤作为庇护所，夜间则沿近海水域移动。本研究揭示，工业开发与突堤等近岸人工设施的建造，可能带来未被预见的负面影响，并对脆弱物种的种群构成显著威胁。