DOCSLIB.ORG

Pacific Island Network Critical Issue Featured Resource Clear, Cool

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Pacific Island Network Critical Issue Featured Resource Clear, Cool National Park Service Pacific Island Network Featured Critical Issue Resource U.S. Department of the Interior Clear, Cool Streams in American Samoa Native Tuna in the Streams ? Sampling stream fauna is an birds, and people. During Tuna (in Samoan), is also known Reproduction: Tuna spend amount of oxygen in the water, exciting part of Inventory & surveys, shrimp are caught as the giant mottled eel, or the their adult lives in freshwater or which makes it more difficult for Monitoring (I&M) Program with nets. Species such as marbled eel (Anguilla marmorata). estuaries, but migrate to the ocean to tuna to breathe. work in the National Park of Atyoida pilipes, Caridina reproduce. Their leaf-shaped larvae American Samoa (NPSA). The weberi, Macrobrachium Additionally, pollution such as Description: This freshwater drift into the ocean and hide among soothing sound of clear, cool lar, and Macrobrachium sewage or agricultural runoff from eel has the widest distribution plankton for about 4 months before water and the welcomed shade latimanus are found during surrounding development further of the anguillid eels. It can be returning to streams. Young migrate of overhanging trees makes stream surveys. depletes oxygen levels in the water. found in the tropical Indo-Pacific upstream feeding and growing for a walk in or along a stream, a Since these animals need to access region from East Africa to French 8-20 years before returning to the stress reducing experience. Fishes, or i’a vai , are the ocean as part of their life cycle, Polynesia as well as rivers in Japan sea to reproduce. But a more compelling reason important food for large they may need to travel through and Mozambique. Adults are long for studying these animals is that The field crew works together to birds. People catch them for food more open areas as part of their and slender and have brown to they are important to the riparian catch stream shrimp. and sport as well. Fish are not journey to or from the ocean. If the black marbling on their backs (stream) ecosystem. collected during surveys but they are amount of dissolved oxygen in the over a greyish yellow base, and a identified and recorded when seen. water is low due to lack of shade white belly. They can reach lengths Snails, or sisi vai, keep algae growth or elevated pollution, the animals' of 2 meters weighing a robust 20 under control. They feed by scraping Stream animals are important progress may be deterred. kilograms, though they typically the algal film from rocks and other indicators of the quality of the water. measure around 80 cm in American surfaces using a ribbon of teeth. Healthy streams naturally have a The Inventory & Monitoring Samoa streams. This species is The size, shape, texture, and color of balanced mix of native animals. Program monitors animal extremely long-lived with age their shells are important features for During stream animal surveys, the populations annually, and water estimates up to 40 years. identification. Snail eggs are attached water quality itself is also analyzed quality parameters quarterly. to submerged rocks or other hard to ensure that streams remain The field crew carefully removes an eel Monitoring includes vital surfaces in streams, or even attached healthy. Habitat and Diet: Don't be from a shrimp net during a survey. measurements such as temperature to the shells of other snails. Although Shrimp are counted, identified, alarmed if you see an eel slithering and dissolved oxygen. and released back to the stream. only a millimeter or two in size, the The I&M Program currently your way. Tuna are capable of Threats: Eels, like all freshwater limited overland travel, especially eggs are easily seen as clusters of monitors three streams on Tutuila fish, are cold-blooded and breathe Giant Mottled Eels in Island. Monitoring Fagatuitui during rainy periods which keep white ovals or sesame-seed shapes using gills. Since they cannot PACN National Parks: against the dark rocks. Species such Stream requires a long hike which their skin moist out of water. regulate body temperature, their The giant mottled eel is common in as Clithon corona, Septaria suffreni, is twice as hard on the way back. In They can be found in all areas of bodies are the same temperature streams on Tutuila and Ta‘u Islands Septaria sanguisuga, Neritina canalis, contrast, Leafu and Amalau Streams the stream from the mouth to the as the water. Temperature affects in the National Park of American and Melaniodes tuberculata are only require a simple stroll from headwaters. They are primarily the eels' metabolism and the Samoa.This species is also found found throughout Samoan streams. nearby villages. In the past, the nocturnal and eat a wide range of amount of oxygen in the stream. In in Asan Stream on the island of Snails are hand collected and I&M Program also sampled Laufuti prey including crabs, fish, and frogs. undeveloped areas with abundant Guam in War in the Pacific National released during the annual surveys. stream on Ta‘u Island, which is less tree cover, the water temperature Historical Park. influenced by humans than the remains relatively constant; Shrimp, ula vai, filter organic debris The field crew meticulously Tutuila Island streams. therefore, the animal’s metabolism —A. Farahi, NPS from flowing water and hunt insect identifies a shrimp. and amount of oxygen in the water Biological Technician larvae hiding among small stones. NPSA’s freshwater animals are will also be relatively constant. They are the most abundant mid- fascinating to study. Sharing this However, in more developed areas sized animals in Samoan streams. experience with others makes it where land has been cleared for Most are only a few centimeters even more enjoyable. housing or agriculture, the water Caught on Video: We long and are well camouflaged. is more exposed to the sun and captured this tuna on video last Others, belonging to the genus temperature fluctuations during the time the stream crew was working Macrobrachium, or "large arm”, are —V. Vaivai, NPS day. The warmer water increases in American Samoa. www.youtube. easier to spot because of their larger Biological Technician the eels' metabolism making them com/watch?v=znXY0WEvvu0 Occasionally, a giant mottled eel will size and bold behavior. Shrimp are A hermit crab decides to take hungrier. The relative warmth move about on land for a short time in an important food source for fishes, some notes of its own. simultaneously decreases the search of food. January 2013 Pacific Island Network .
Load more

Recommended publications
  • Drawing No. MCL/P132/EIA/12-025B
    H1 H4 H1 H8 F2/F7 Butterfly Dragonfly B1 Aeromachus jhora Grey Scrub Hopper D1 Melligomphus moluami Small Hooktail B2 Appias albina darada Common Albatross Freshwater Fish B3 Arhopala birmana birmana Burmese Bush Blue F1 Acrossocheilus beijiangensis Beijiang Thick-lipped Barb B4 Caltoris cahira Dark Swift F2 Anguilla marmorata Giant Mottled Eel B5 Dichorragia nesimachus formosanus Constable F3 Cirrhinus molitorella Mud Carp B6 Eurema brigitta rubella Small Grass Yellow F4 Cyprinus carpio Common Carp B7 Eurema laeta betheseba Spotless Grass Yellow F5 Glyptothorax pallozonum White-line Chest-sculptured Sisoridfish B8 Hasora chromus chromus Banded Awl F6 Oryzias curvinotus Rice Fish B9 Junonia hierta hierta Yellow Pansy F7 Parazacco spilurus Predaceous Chub B10 Lamproptera curius walkeri White Dragontail F8 Plecoglossus altivelis Ayu B11 Leptotes plinius Oriental Striped Blue F9 Stiphodon atropurpureus Purple Neon Goby B12 Megisba malaya sikkima Malayan Freshwater Macroinvertebrate B13 Neptis soma tayalina Sullied Sailer M1 Metapenaeus ensis Greasyback Shrimp B14 Pachliopta aristolochiae goniopeltis Common Rose M2 Somanniathelphusa zanklon Freshwater Crab Species B15 Papilio xuthus xuthus Swallowtail Herpetofauna B16 Parnara bada bada Oriental Straight Swift H1 Gekko reevesii Tokay Gecko B17 Pelopidas conjunctus conjunctus Conjoined Swift H2 Hoplobatrachus chinensis Chinese Bullfrog B18 Potanthus pava pava Yellow Band Dart H3 Liuixalus romeri Romer’s Tree Frog B19 Potanthus trachala trachala Lesser Band Dart H4 Naja atra Chinese Cobra B20
    [Show full text]
  • Li Lian WONG1, Siti Raudah ABDUL KADIR2, Rabi Atun ADAWIAH ABDULLAH1, Charlie Albert LASUIN3, Kok Onn KWONG4, and Takaomi ARAI5*
    ACTA ICHTHYOLOGICA ET PISCATORIA (2017) 47 (1): 73–79 DOI: 10.3750/AIEP/02072 EVIDENCE SUPPORTING THE OCCURRENCE AND THE ECOLOGICAL IMPLICATION OF GIANT MOTTLED EEL, ANGUILLA MARMORATA (ACTINOPTERYGII: ANGUILLIFORMES: ANGUILLIDAE), FROM SABAH, BORNEO ISLAND Li Lian WONG1, Siti Raudah ABDUL KADIR2, Rabi Atun ADAWIAH ABDULLAH1, Charlie Albert LASUIN3, Kok Onn KWONG4, and Takaomi ARAI5* 1Institute of Tropical Aquaculture, Universiti Malaysia Terengganu, Kuala Terengganu, Terengganu, Malaysia 2Institute of Oceanography and Environment, Universiti Malaysia Terengganu, Kuala Terengganu, Terengganu, Malaysia 3Faculty of Business, Economics and Accountancy, Universiti Malaysia Sabah, Kota Kinabalu, Sabah, Malaysia 4School of Biological Sciences, Universiti Sains Malaysia, Minden, Penang, Malaysia 5Environmental and Life Sciences Programme, Faculty of Science, Universiti Brunei Darussalam, Brunei Darussalam Wong L.L., Abdul Kadir S.R., Adawiah Abdullah R.A., Lasuin C.A., Kwong K.O., Arai T. 2017. Evidence supporting the occurrence and the ecological implication of giant mottled eel, Anguilla marmorata (Actinopterygii: Anguilliformes: Anguillidae), from Sabah, Borneo Island. Acta Ichthyol. Piscat. 47 (1): 73–79. Abstract. Although tropical anguillid eels account for two-thirds of all species in the genus Anguilla, the information on the species diversity, geographic distribution, and life histories of the tropical eels is very limited. Recent studies suggested that accurate species identification in the tropical anguillid eels needs a validation by molecular genetic analysis after morphological observation. Two anguillid eels found in Sabah, Borneo Island, were firstly identified as Anguilla marmorata Quoy et Gaimard, 1824 using morphological analysis and further analysis of mitochondrial 16S ribosomal RNA (16S rRNA) sequences confirmed the morphological species identification. The presently reported study represents the first description of A.
    [Show full text]
  • Fish, Various Invertebrates
    Zambezi Basin Wetlands Volume II : Chapters 7 - 11 - Contents i Back to links page CONTENTS VOLUME II Technical Reviews Page CHAPTER 7 : FRESHWATER FISHES .............................. 393 7.1 Introduction .................................................................... 393 7.2 The origin and zoogeography of Zambezian fishes ....... 393 7.3 Ichthyological regions of the Zambezi .......................... 404 7.4 Threats to biodiversity ................................................... 416 7.5 Wetlands of special interest .......................................... 432 7.6 Conservation and future directions ............................... 440 7.7 References ..................................................................... 443 TABLE 7.2: The fishes of the Zambezi River system .............. 449 APPENDIX 7.1 : Zambezi Delta Survey .................................. 461 CHAPTER 8 : FRESHWATER MOLLUSCS ................... 487 8.1 Introduction ................................................................. 487 8.2 Literature review ......................................................... 488 8.3 The Zambezi River basin ............................................ 489 8.4 The Molluscan fauna .................................................. 491 8.5 Biogeography ............................................................... 508 8.6 Biomphalaria, Bulinis and Schistosomiasis ................ 515 8.7 Conservation ................................................................ 516 8.8 Further investigations .................................................
    [Show full text]
  • True Eels Or Freshwater Eels - Anguillidae
    ISSN 0859-290X, Vol. 5, No. 1 – September 1999 [Supplement No. 6] Even if the eels, in the perception of most people, constitute a readily recognizable group of elongated and snakelike fish, the eels do not constitute a taxonomic group. There is considerable confusion related to eels. See the following system used in "Fishes of the Cambodian Mekong" by Walther Rainboth (1996). In the Mekong, two orders (Anguilliformes and Synbranchiformes) including five eel-Iike fish families are represented: The true eels (Anguillidae), the worm eels (Ophichthidae), the dwarf swamp eels (Chaudhuriidae), the swamp eels (Synbranchidae), and the spiny eels (Mastacembelidae). Of these, the swamp eels and spiny eels are by far the most important in the fisheries. True eels or Freshwater eels - Anguillidae The name "freshwater eels", is not a good name to describe the habits of the species in this family. All the anguillid species are catadromous (a catadromous fish is bom in the sea, but lives most of its life in fresh water). The sexually mature fish migrate down to the sea to spawn, and the juveniles ("the elvers") move, sometimes for a considerable distance, up the river to find their nursery areas. The true eels, contrary to most of the other Mekong eels, have two gill openings, which are high on each side of the fish. The body is covered with small scales that are deeply embedded in the skin. Pelvic fins are absent, while pectoral fins are well developed. The long dorsal and anal fins are continuous with the caudal fin, and the fins are not preceded by any spines.
    [Show full text]
  • Publication: CNMI DFW. 2008. Freshwater Invasive Species Project
    1 Table of Contents Preliminary Contents pg Title Page 1 Table of Contents 2 Section Description pg I. Introduction 4 II. Materials and Methods 6 III. Site Descriptions 8 IV. Results 16 V. Discussion & Recommendations 20 VI. Bibliography 22 Graphic Description pg Table-1 Physical Characteristics of Sampling Sites 16 Table-2 Chemical Characteristics of Sampling Sites 16 Table-3 Species findings at sampling sites 17 Table-4 Method Effort Comparison 17 Figure-1 Saipan Map with Site Locations 3 Figure-2 Method Efficiency Comparison 18 Figure-3 Method Efficiency Regression Analysis 19 Appendix Description pg Appendix A Freshwater Species Sheets 24 Appendix B Field Data Form 52 Appendix C Laboratory Data Form 53 Appendix D Field Photos & Diagrams 54 Appendix E Source Site Conditions Data 67 Appendix F Source Lab Data 71 Appendix G Electrofishing Course Description 78 Appendix H Bishop Museum Gene Sequence Report 80 2 Figure-1 Saipan Map with Site Locations 3 I. Introduction Very little was known about the freshwater ecosystems of the Commonwealth of the Northern Marianna Islands (CNMI) or the species that inhabit them prior to this study. Most information was both unpublished and anecdotal (Best 1981). Derek Stinson put a report together nearly twenty years ago, which defines most of the major wetland areas of the CNMI and provides some background information for larger lentic systems like Lake Susupe, but doesn’t mention any of our interstitial stream systems (Stinson 1990). An examination of freshwater fishes in the CNMI using Fishbase, a comprehensive fisheries web resource, lists 13 native and 2 introduced species (Froese 2008).
    [Show full text]
  • Oceanic Spawning Ecology of Freshwater Eels in the Western North Pacific
    ARTICLE Received 18 Jun 2010 | Accepted 22 Dec 2010 | Published 1 Feb 2011 DOI: 10.1038/ncomms1174 Oceanic spawning ecology of freshwater eels in the western North Pacific Katsumi Tsukamoto1, Seinen Chow2, Tsuguo Otake3, Hiroaki Kurogi2, Noritaka Mochioka4, Michael J. Miller1, Jun Aoyama1, Shingo Kimura5, Shun Watanabe1, Tatsuki Yoshinaga6, Akira Shinoda1,7, Mari Kuroki1,8, Machiko Oya1, Tomowo Watanabe9, Kazuhiro Hata10, Shigeho Ijiri11, Yukinori Kazeto12, Kazuharu Nomura13 & Hideki Tanaka13 The natural reproductive ecology of freshwater eels remained a mystery even after some of their offshore spawning areas were discovered approximately 100 years ago. In this study, we investigate the spawning ecology of freshwater eels for the first time using collections of eggs, larvae and spawning-condition adults of two species in their shared spawning area in the Pacific. Ovaries of female Japanese eel and giant mottled eel adults were polycyclic, suggesting that freshwater eels can spawn more than once during a spawning season. The first collection of Japanese eel eggs near the West Mariana Ridge where adults and newly hatched larvae were also caught shows that spawning occurs during new moon periods throughout the spawning season. The depths where adults and newly hatched larvae were captured indicate that spawning occurs in shallower layers of 150–200 m and not at great depths. This type of spawning may reduce predation and facilitate reproductive success. 1 Department of Marine Bioscience, Atmosphere and Ocean Research Institute, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8564, Japan. 2 Coastal Fisheries and Aquaculture Division, National Research Institute of Fisheries Science, Fisheries Research Agency, Yokosuka, Kanagawa 238-0316, Japan.
    [Show full text]
  • (Cd, Pb and Hg) Elements in Muscle Tissues of Anguilla Bicolor Bicolor
    Jurnal Sains Kesihatan Malaysia 17(2) 2019: 63-72 DOI : http://dx.doi.org./10.17576/JSKM-2019-1702-07 Artikel Asli/Original Articles Levels of Non-Essential (Cd, Pb and Hg) Elements in Muscle Tissues of Anguilla bicolor bicolor, McClelland 1844 from Kedah and Anguilla bengalensis bengalensis, Gray 1831 from Perak and Human Consumption Risks (Kepekatan Unsur Tidak Perlu (Cd, Pb dan Hg) dalam Tisu Otot Anguilla bicolor bicolor, McClelland 1844 dari Kedah dan Anguilla bengalensis bengalensis, Gray 1831 dari Perak serta Risiko ke Atas Konsumer Manusia) NORAIFAA ABDULLAH SANI, NOOR AZHAR MOHAMED SHAZILI, ONG MENG CHUAN & TAKAOMI ARAI ABSTRACT A study on heavy metals accumulation and human health risk assessment in the consumption of two tropical freshwater eel species (Anguilla bengalensis bengalensis) from the Sungai Perak at Kuala Kangsar, Perak and (Anguilla bicolor bicolor) from the Air Hitam irrigation canal, Kampung Kuala Sanglang, Kedah was carried out. Specimens were examined and analyzed for Pb and Cd concentrations using ICP-MS while the total Hg concentration was measured using a direct mercury analyzer (MA-3000). The range for the total concentrations (µg/g wet wt.) in Anguilla bicolor bicolor were 0.01-0.4 (Cd), 0.03-0.77 (Pb) and 0.36-0.94 (Hg) while for Anguilla bengalensis bengalensis, they were 0.76-1.23 (Cd), 0.01-0.10 (Pb) and 0.27-1.5 (Hg). Anguilla bengalensis bengalensis (Sungai Perak) showed a significant strong relationship between Hg/Pb (r = .771, P < 0.05) and Anguilla bicolor bicolor (Air Hitam irrigation canal) with Cd/ Pb (r = -.895, P < 0.05) in muscle tissues and the results indicated Hg and Pb were introduced from point and non- point sources, therefore it is of concern.
    [Show full text]
  • Ages of the Giant Mottled Eel Anguilla Marmorata Recruited at the Northern Luzon Island, the Philippines Between 2009 and 2011
    Coastal Marine Science 39(1): 1–4, 2016 Ages of the giant mottled eel Anguilla marmorata recruited at the northern Luzon Island, the Philippines between 2009 and 2011 Sho Nakazato1, Takuya Minagawa1, Fumiaki Shirotori1, Akira Shinoda2, Jun Aoyama3 and Tatsuki Yoshinaga1* 1 School of Marine Biosciences, Kitasato University, Kanagawa 252–0373, Japan 2 Department of Biology, Tokyo Medical University, Tokyo 160–8402, Japan 3 Atmosphere and Ocean Research Institute, the University of Tokyo, Chiba 277–8564, Japan * E-mail: [email protected] Received 17 April 2015; Accepted 7 May 2015 Abstract― To accumulate information on the larval transportation of the freshwater eels in the North Pacific, we examined the ages of the giant mottled eel Anguilla marmorata recruited at the northern Philippines. The glass eel specimens analyzed were collected at the river mouth of the Cagayan River in the Luzon Island in January 2009, November 2011 and November 2012, and the daily increment rings of the otoliths were observed to determine the ages at recruitment (n=14). There was no significant dif- ference in the ages at recruitment among the 2009- (147.0 ± 24.4 days; 126–182), 2011- (145.2 ± 17.3; 122–161) and 2012-groups (136.0 ± 11.1; 122–145), and were in the range of those in the previous studies at the same place. Further efforts to accumulate in- formation on the ages at recruitment at various localities and timings will be important to comprehensively understand the early life history of A. marmorata in the North Pacific. Key words: Anguilla marmorata, freshwater eel, giant mottled eel, glass eel, otolith, Philippines Introduction moto et al.
    [Show full text]
  • A Revised and Updated Checklist of the Parasites of Eels (Anguilla Spp.) (Anguilliformes: Anguillidae) in Japan (1915-2017)
    33 69 生物圏科学 Biosphere Sci. 56：33－69 (2017) A revised and updated checklist of the parasites of eels (Anguilla spp.) (Anguilliformes: Anguillidae) in Japan (1915-2017) 1) 2) Kazuya NAGASAWA and Hirotaka KATAHIRA 1) Graduate School of Biosphere Science, Hiroshima University, 1-4-4 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8528, Japan 2) Faculty of Bioresources, Mie University, 1577 Kurima machiya-cho, Tsu, Mie 514-8507, Japan Published by The Graduate School of Biosphere Science Hiroshima University Higashi-Hiroshima 739-8528, Japan November 2017 生物圏科学 Biosphere Sci. 56：33－69 (2017) REVIEW A revised and updated checklist of the parasites of eels (Anguilla spp.) (Anguilliformes: Anguillidae) in Japan (1915-2017) 1) 2) Kazuya NAGASAWA * and Hirotaka KATAHIRA 1) Graduate School of Biosphere Science, Hiroshima University, 1-4-4 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8528, Japan 2) Faculty of Bioresources, Mie University, 1577 Kurima machiya-cho, Tsu, Mie 514-8507, Japan Abstract Information on the protistan and metazoan parasites of four species of eels (the Japanese eel Anguilla japonica, the giant mottled eel Anguilla marmorata, the European eel Anguilla anguilla, and the short-finned eel Anguilla australis) in Japan is summarized in the Parasite-Host and Host- Parasite lists, based on the literature published for 103 years between 1915 and 2017. This is a revised and updated version of the checklist published in 2007. Anguilla japonica and A. marmorata are native to Japan, whereas A. anguilla and A. australis are introduced species from Europe and Australia, respectively. The parasites, including 54 nominal species and those not identified to species level, are listed by higher taxa as follows: Sarcomastigophora (no.
    [Show full text]
  • Biology and Ecology of Aqua-Sphere
    Chapter II BIOLOGY AND ECOLOGY OF AQUA-SPHERE Toyoji KANEKO, Katsumi TSUKAMOTO, Atsushi TSUDA, Yuzuru SUZUKI and Katsufumi SATOH Irrespective of the nature of the environment, whether it is the sea, river, lake or pond, organisms make even the hot spring and ground water as their habitat. Organisms living in the earth’s aquasphere are called aquatic organisms. Primeval forms of life were born and a major part of history of evolution has progressed in the sea. Therefore, biodiversity in the aquasphere, which has several endemic species, is higher than that in aerosphere and terrasphere. We can find all phyla of prokaryotes, protists, fungi, plants and animals in the aquatic environment. Animals that have strong connection with aquatic environment in their life such as the seabirds and seals are also members of aquatic organisms, and constitute a part of the ecosystem through interrelationships among them. The aquatic environments can be differentiated into riverine, coastal, and deep sea ecosystem. However, as most water bodies on earth including the seas and inland water bodies have some connections to other water bodies, the boundary of the ecosystems is obscure. Ecosystems are connected through migration of organisms and material transportation. In order to live in water, aquatic organisms have developed specialized adaptive functions and organs. The endemic and common organs, tissues and cells such as gills, lateral line, swim-bladder and chloride cells are some examples. These functions characterize not only the behavior of aquatic organisms but also their life history, population structure, reproduction, feeding, migration etc. For example, being denser than air, water offers higher buoyancy to organisms thereby helping large scale dispersion at larval stage, which is a common characteristic trait in aquatic species.
    [Show full text]
  • Oceanic Migration Behaviour of Tropical Pacific Eels from Vanuatu
    Vol. 475: 177–190, 2013 MARINE ECOLOGY PROGRESS SERIES Published February 14 doi: 10.3354/meps10254 Mar Ecol Prog Ser Oceanic migration behaviour of tropical Pacific eels from Vanuatu Robert Schabetsberger1,*, Finn Økland2, Kim Aarestrup3, Donna Kalfatak4, Ursula Sichrowsky5, Meelis Tambets6, Giorgio Dall’Olmo7, Roland Kaiser1, Peter I. Miller7 1Department of Cell Biology, University of Salzburg, 5020 Salzburg, Austria 2The Norwegian Institute of Nature Research, 7047 Trondheim, Norway 3Denmark Technical University, 8600 Silkeborg, Denmark 4Department of Environmental Protection and Conservation, Port Vila, Vanuatu 5Department of Limnology, University of Innsbruck, 6020 Innsbruck, Austria 6Estonian Marine Institute, University of Tartu, Mäealuse 14, 12618 Tallinn, Estonia 7Plymouth Marine Laboratory, Plymouth PL1 3DH, UK ABSTRACT: 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 mar- morata (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. All 3 species exhibited pronounced diel vertical migrations. Eels descended from around 200 m nighttime depth, to 320 (A. obscura), 650 (A. marmorata), and 750 m (A. megastoma) during the day. A clear impact of the lunar cycle on the upper limit of migration depths was found in A.
    [Show full text]
  • Opportunistic Migration and Habitat Use of the Giant Mottled Eel
    www.nature.com/scientificreports OPEN Opportunistic migration and habitat use of the giant mottled eel Anguilla marmorata (Teleostei: Received: 27 October 2017 Accepted: 26 March 2018 Elopomorpha) Published: xx xx xxxx Takaomi Arai 1 & Naoko Chino2 Freshwater eels have fascinated biologists for centuries due to the spectacular long-distance migrations between their freshwater habitats and their spawning areas far out in the ocean. Although freshwater eels originated in the Indonesian region, remarkably little is known about the life history of tropical freshwater eels. The diverse migratory patterns and habitat choice between marine and freshwater environments by the giant mottled eel Anguilla marmorata Quoy & Gaimard, 1824 were examined by analysing the otolith strontium (Sr) and calcium (Ca) concentrations collected in Asian waters. The wide range of otolith Sr:Ca ratios indicated that the habitat use of A. marmorata was opportunistic among fresh, brackish, and marine waters. The present study frst confrmed the occurrence of marine- resident eels that have never migrated into a freshwater habitat in A. marmorata. A. marmorata may have the same behavioural plasticity as temperate and other tropical anguillid species regarding whether to enter freshwater or to remain in estuarine and marine environments. Freshwater eels migrate fexibly among freshwater, brackish water, and seawater environments and it is now evident that their movement into freshwater is not an obligate migratory pathway but should be defned as an opportunistic catadromy, with marine and estuarine residents as ecophenotypes. Freshwater eels of the genus Anguilla, being catadromous1, migrate between freshwater growth habitats and of- shore spawning areas. Nineteen species/subspecies of Anguilla have been reported world-wide, thirteen of which are known to occur in tropical regions2,3 that are globally distributed in temperate, tropical, and subtropical areas.
    [Show full text]