Описание
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.
Записи данных
Данные этого sampling event ресурса были опубликованы в виде Darwin Core Archive (DwC-A), который является стандартным форматом для обмена данными о биоразнообразии в виде набора из одной или нескольких таблиц. Основная таблица данных содержит 6 записей.
Также в наличии 2 таблиц с данными расширений. Записи расширений содержат дополнительную информацию об основной записи. Число записей в каждой таблице данных расширения показано ниже.
Данный экземпляр IPT архивирует данные и таким образом служит хранилищем данных. Данные и метаданные ресурсов доступны для скачивания в разделе Загрузки. В таблице версий перечислены другие версии ресурса, которые были доступны публично, что позволяет отслеживать изменения, внесенные в ресурс с течением времени.
Версии
В таблице ниже указаны только опубликованные версии ресурса, которые доступны для свободного скачивания.
Как оформить ссылку
Исследователи должны дать ссылку на эту работу следующим образом:
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
Права
Исследователи должны соблюдать следующие права:
Публикующей организацией и владельцем прав на данную работу является Southwestern Pacific Ocean Biogeographic Information System (OBIS) Node. Эта работа находится под лицензией Creative Commons Attribution (CC-BY 4.0).
Регистрация в GBIF
Этот ресурс был зарегистрирован в GBIF, ему был присвоен следующий UUID: 58eada0b-0178-454a-a823-45205d42f9fd. Southwestern Pacific Ocean Biogeographic Information System (OBIS) Node отвечает за публикацию этого ресурса, и зарегистрирован в GBIF как издатель данных при оподдержке Ocean Biodiversity Information System.
Ключевые слова
Samplingevent
Контакты
- Metadata Provider ●
- Originator ●
- Point Of Contact
- Originator
- Originator
- Originator
- Originator
- Originator
- Originator
- Originator
- Originator
Географический охват
Vanuatu and surrounding ocean
| Ограничивающие координаты | Юг Запад [-15,717, 166,587], Север Восток [-8,77, 173,016] |
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Таксономический охват
Eels, genus Anguilla
| Species | Anguilla marmorata, Anguilla megastoma, Anguilla obscura |
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Временной охват
| Дата начала / Дата окончания | 2012-02-02 / 2012-05-02 |
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Методы сбора
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.
| Охват исследования | 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. |
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Описание этапа методики:
- 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.
Библиографические ссылки
- 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.
Дополнительные метаданные
marine, harvested by iOBIS
| Альтернативные идентификаторы | https://nzobisipt.niwa.co.nz/resource?r=vanuatu_eels |
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