說明
Information on oceanic migrations and spawning areas of tropical Pacific freshwater eels (genus Anguilla) is very limited. Lake Letas and its single outflowing river, Mbe Solomul on Gaua Island, Vanuatu, were surveyed for large migrating individuals. Twenty-four Anguilla marmorata (87 to 142 cm), 39 A. megastoma (50 to 131 cm), and 3 A. obscura (119 to 126 cm) were caught. Seven individuals were tagged with pop-up satellite transmitters and released offshore. One A. marmorata migrated 843 km towards the South Equatorial Current. The tag surfaced only 330 km from the point where the smallest leptocephalus has been captured so far. Tags on A. megastoma and A. obscura popped up within the archipelago.
資料紀錄
此資源sampling event的資料已發佈為達爾文核心集檔案（DwC-A），其以一或多組資料表構成分享生物多樣性資料的標準格式。 核心資料表包含 6 筆紀錄。
亦存在 2 筆延伸集的資料表。延伸集中的紀錄補充核心集中紀錄的額外資訊。 每個延伸集資料表中資料筆數顯示如下。
此 IPT 存放資料以提供資料儲存庫服務。資料與資源的詮釋資料可由「下載」單元下載。「版本」表格列出此資源的其它公開版本，以便利追蹤其隨時間的變更。
版本
以下的表格只顯示可公開存取資源的已發布版本。
如何引用
研究者應依照以下指示引用此資源。:
Schabetsberger R, Økland F, Aarestrup K, Kalfatak D, Sichrowsky U, Tambets M, Dall’Olmo G, Kaiser R, Miller P I (2024). Oceanic migration of tropical Pacific eels from Vanuatu. Version 1.0. Southwestern Pacific Ocean Biogeographic Information System (OBIS) Node. Samplingevent dataset. https://nzobisipt.niwa.co.nz/resource?r=vanuatu_eels&v=1.0
權利
研究者應尊重以下權利聲明。:
此資料的發布者及權利單位為 Southwestern Pacific Ocean Biogeographic Information System (OBIS) Node。 This work is licensed under a Creative Commons Attribution (CC-BY 4.0) License.
GBIF 註冊
此資源已向GBIF註冊，並指定以下之GBIF UUID: 58eada0b-0178-454a-a823-45205d42f9fd。 Southwestern Pacific Ocean Biogeographic Information System (OBIS) Node 發佈此資源，並經由Ocean Biodiversity Information System同意向GBIF註冊成為資料發佈者。
關鍵字
Samplingevent
聯絡資訊
- 元數據提供者 ●
- 出處 ●
- 連絡人
- 出處
- 出處
- 出處
- 出處
- 出處
- 出處
- 出處
- 出處
地理涵蓋範圍
Vanuatu and surrounding ocean
| 界定座標範圍 | 緯度南界 經度西界 [-15.717, 166.587], 緯度北界 經度東界 [-8.77, 173.016] |
|---|
分類群涵蓋範圍
Eels, genus Anguilla
| Species | Anguilla marmorata, Anguilla megastoma, Anguilla obscura |
|---|
時間涵蓋範圍
| 起始日期 / 結束日期 | 2012-02-02 / 2012-05-02 |
|---|
取樣方法
Between 17 January and 2 February 2012, Lake Letas and its outflow were surveyed for silver eels by electrofishing, hooks, hook and line, and fyke nets in collaboration with fishermen from Gaua. The research team (R. Schabetsberger, F. Økland D. Kalfatak, U. Sichrowsky, M. Tambets) then anaesthetized, photographed, and measured the fish before they were either released (17 including tagged fish) or sacrificed (49) and given to local families.
| 研究範圍 | Gaua Island (Banks Group, Vanuatu) is the emerged top of a 3000 m high and 40 km wide stratovolcano. The symmetrical cone of approx. 25 km diameter is truncated between 500 and 690 m altitude by an 8.5 × 6 km central caldera. Its active volcano Mt. Garet (979 m a.s.l., 350 m high, base 3 km) towers over the crescent-shaped Lake Letas (100 m depth, 7 × 2 km, 418 m a.s.l.), which is constantly fertilized by the inflow of nutrient-rich, warm volcanic springs. Oxygen is available all the way to the deepest point (100 m), and abundant invertebrate life provides rich food resources (Schabetsberger unpubl. obs.). Migrating eels leave the lake through the outflowing Mbe Solomul River. It falls over a 120 m high cascade (Siri Falls) and bifurcates into 1 larger (18 m3 s−1) and 2 smaller rivers (0.9 and 6.1 m3 s−1) before entering the sea. Flow rates increase significantly during heavy rain. According to the experience of local fishermen, eels predominantly leave Lake Letas during heavy rains and north-westerly winds between January and March but may emigrate throughout the year. A tropical depression hitting the island on 24 January 2012 yielded silvering eels in the lower stretches of the flooding river several days later. |
|---|
方法步驟描述:
- Total length, distance from lower jaw to anus, to dorsal fin, and to gill opening, as well as length of mouth and length of pectoral fin were measured with a measuring tape to the nearest mm. Horizontal and vertical eye diameter was measured to the nearest 0.1 mm with ruler callipers. Weight measurements were taken on a Voltcraft HS-30 balance to the nearest 10 g. All eel species were determined through analysis of body proportions and dentition of the upper jaw (Ege 1939, p. 248–251). Colouration of the total body and the relative size of the eyes (Okamura et al. 2007) were used to classify silver eels. The stomachs of 7 Anguilla marmorata (4 yellow/3 silver) and 13 A. mega stoma (9/4) were opened and checked for contents.
- During the last 3 days of fishing operations, 7 eels with a silvery appearance (1 Anguilla marmorata, 4 A. megastoma, 2 A. obscura) were caught for tagging by local fishermen at the banks of the main river below Siri Falls, where fish are frequently found in shallow water after plummeting over the cascade. The single A. marmorata was caught near the mouth of the river. The tags were put on 3 different species, because we were unable to catch enough silver eels of the original target species A. megastoma. Due to the strong current that prevented the use of other fishing gear, the animals were pulled out from littoral hiding places with metal hooks mounted on wooden poles and pushed into hand-nets, resulting in minor skin lesions (ca. 1 cm) behind the anus. The small wounds were not treated with antibiotics, nor were they sutured to avoid the inclusion of anaerobic germs (F. Økland pers. obs.).
- After measuring, 2 types of satellite pop-up transmitters were deployed. Two eels were tagged with Mini-Pats (Wildlife Computers, Type 1), and the remaining 5 individuals, with X-tags (Microwave Telemetry, Type 2). Type 1 tags were provided for free by the manufacturer, and Type 2 tags were refurbished with new batteries after use in a previous project. The Type 1 tag is 11.5 cm long (excluding antenna), 40 mm wide and weighs 53 g in air. The Type 2 tag measures 12 cm in length, is 32 mm wide, and weighs 42 g.
- The tags were pre-programmed to surface after 3 mo assuming that the eels spawn north of Fiji and migrate with a speed of approximately 15 km d−1, based on the discovery of leptocephali east of Gaua (Kuroki et al. 2008) and the migration speed of similar-sized Anguilla dieffenbachii (Jellyman & Tsukamoto 2002). In case of premature death of the host or detachment of the tag, the transmitters were programmed to initiate a failsafe release mechanism, ascend to the surface, and transmit data. A depth reading deeper than 2100 m (pressure transducer sensor range exceeded) or 4 d of equal depth readings (±10 m) would initiate this mechanism.
引用文獻
- Schabetsberger, R., Økland, F., Aarestrup, K., Kalfatak, D., Sichrowsky, U., Tambets, M., Dall’Olmo, G., Kaiser, R. and Miller, P.I., 2013. Oceanic migration behaviour of tropical Pacific eels from Vanuatu. Marine Ecology Progress Series, 475, pp.177-190.
額外的詮釋資料
marine, harvested by iOBIS