Brooks E.J.,Cape Eleuthera Institute |
Brooks A.M.L.,Cape Eleuthera Institute |
Williams S.,Cape Eleuthera Institute |
Jordan L.K.B.,Microwave Telemetry Inc. |
And 4 more authors.
Deep-Sea Research Part II: Topical Studies in Oceanography | Year: 2015
Deep-sea chondrichthyans, like many deep-water fishes, are very poorly understood at the most fundamental biological, ecological and taxonomic levels. Our study represents the first ecological investigation of deep-water elasmobranch assemblages in The Bahamas, and the first assessment of species-specific resilience to capture for all of the species captured. Standardised deep-water longline surveys (n=69) were conducted September to December 2010 and 2011 between 472. m and 1024. m deep, resulting in the capture of 144 sharks from 8 different species. These included the Cuban dogfish, Squalus cubensis, the bigeye sixgill shark, Hexanchus nakamurai, the bluntnose sixgill shark, Hexanchus griseus, the smooth dogfish, Mustelus canis insularis, the roughskin dogfish, Centroscymnus owstoni, Springer[U+05F3]s sawtail catshark, Galeus springeri and the false catshark, Pseudotriakis microdon. Preliminary genetic analysis indicated two or more species of gulper sharks, Centrophorus spp.; however, for the present study they were treated as a single species complex. Water depth and distance from the rocky structure of the Exuma Sound wall were inversely correlated with species richness, whereas seabed temperature was directly correlated with species richness. These variables also had a significant influence on the abundance and distribution of many species. Expanded depth ranges were established for S. cubensis and H. nakamurai, which, in the case of S. cubensis, is thought to be driven by thermal preferences. At-vessel mortality rates increased significantly with depth, and post-release mortality was thought to be high for some species, in part due to high post-release predation. This study highlights the importance of utilising strategic geographic locations that provide easy access to deep water, in combination with traditional expedition-based deep-ocean science, to accelerate the acquisition of fundamental ecological and biological insights into deep-sea elasmobranchs. © 2015 Elsevier Ltd.
Meyburg B.-U.,Wangenheimstr. 32 |
Howey P.W.,Microwave Telemetry Inc. |
Fiuczynski K.D.,Westfalenring 26
British Birds | Year: 2011
A prototype of the smallest satellite transmitter produced so far, weighing just 5 g.was fitted to an adult Hobby Falco subbuteo in Germany in August 2008. Two autumn and two spring migrations were recorded successfully from the unit carried by this particular Hobby. All four migration routes were to the west of a direct line between breeding site and wintering area. The migration route in spring 2010 was up to 2,150 km farther west than that in autumn 2009, effectively forming a 'migration loop'. This was much less pronounced in 2008/09. The direct distance from the breeding site to the southernmost point reached in Zimbabwe in 2008/09 was 10,065 km. The fastest flight speeds on migration were recorded in spring 2010 in Mali and Morocco, when 1,243 km was covered in two days. Also in spring 2010, during migration from Morocco to southern France ( 1,032 km in two days), the falcon migrated at night, when a fix was made over the Mediterranean in the vicinity of Gibraltar. Migration across the Sahara took 4-4.5 days on each migration. The West African equatorial rainforest appears to be a significant ecological barrier, and the significance of this is discussed. Migration was noticeably rapid there with distances of up to 580 km flown per day - also partly at night. During both wintering periods the falcon spent the majority of its time in the Angolan Miombo woodlands, but in winter it also travelled large distances: from 16th October 2008 to 7th April 2009, the bird covered a total distance of at least 9,025 km between identified night roosts. In 2009, the bird spent half the year in the wintering area, a third on the breeding grounds and the remaining 18% of the time on migration; i.e. 65% of its time in Africa and 35% in Europe. © British Birds 104.
Camargo S.M.,Paulista University |
Camargo S.M.,Federal University of Sao Paulo |
Coelho R.,Instituto Portugues Do Mar e DaAtmosfera IPMA |
Coelho R.,University of Algarve |
And 11 more authors.
PLoS ONE | Year: 2016
Information regarding population structure and genetic connectivity is an important contribution when establishing conservation strategies to manage threatened species. The oceanic whitetip shark, Carcharhinus longimanus, is a highly migratory, large-bodied, pelagic shark listed by the IUCN (International Union for Conservation of Nature) Red List as "vulnerable" throughout its range and "critically endangered" in the western north Atlantic. In 2014, the species was protected globally under Appendix II of CITES (Convention on International Trade in Endangered Species), limiting and regulating trade. This study used partial sequences of mitochondrial DNA (mtDNA) control region to determine the population genetic structure of oceanic whitetip sharks across the Atlantic and Indian Oceans. 724 base pairs were obtained from 215 individuals that identifed nine polymorphic sites and defined 12 distinct haplotypes. Total nucleotide diversity (τ) was 0.0013 and haplotype diversity (h) was 0.5953. The Analysis of Molecular Variance (AMOVA) evidenced moderate levels of population structure (ØST = 0.1039) with restricted gene flow between the western and eastern Atlantic Ocean, and a strong relationship between the latter region and the Indian Ocean. Even though the oceanic whitetip is a highly migratory animal the results presented here show that their genetic variability is slightly below average of other pelagic sharks. Additionally, this study recommends that at least two populations in the Atlantic Ocean should be considered distinct (eastern and western Atlantic) and conservation efforts should be focused in areas with the greatest genetic diversity by environmental managers. © 2016 Camargo et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Madigan D.J.,State University of New York at Stony Brook |
Brooks E.J.,Cape Eleuthera Institute |
Bond M.E.,State University of New York at Stony Brook |
Gelsleichter J.,University of North Florida |
And 4 more authors.
Marine Ecology Progress Series | Year: 2015
Identifying the driving forces behind oceanic pelagic shark movements is key to a better understanding of their life history. Some oceanic pelagic shark species have been shown to aggregate in specific regions to mate and/or exploit abundant food resources. The oceanic whitetip shark Carcharhinus longimanus, a subtropical, ectothermic, oceanic pelagic shark that has experienced severe population declines, aggregates seasonally around Cat Island (CI) in The Bahamas. Large pelagic teleosts (e.g. billfish, tunas, and dolphinfish) are abundant in this region and oceanic whitetips are anecdotally reported to feed heavily on recreationally caught teleosts. However, it was unknown whether feeding habits at CI substantially differ from longer-term feeding habits. We used tag-recapture to assess site-fidelity of adult oceanic whitetips to CI and stable isotope analysis (SIA) of 2 different tissues (blood plasma and white muscle) to compare short- and long-term feeding patterns. The relatively high recapture rate (20.3%) confirmed that individual whitetips exhibit site-fidelity to CI. The aggregation consisted of adult individuals; females were more common, more than half were gravid, and no physical or behavioral evidence of mating or parturition was observed at CI. SIA-based Bayesian mixing model estimates of short-term (near CI) diets showed more large pelagic teleosts (72%) than in long-term diets (47%), showing a spatiotemporal difference in oceanic whitetip feeding habits. This suggests that availability of large teleost prey is a possible mechanism underpinning site-fidelity and aggregation of whitetips at CI. These results provide insight into the function of one of the last known aggregations of this once-abundant top predator. © Inter-Research 2015.
Hoffmayer E.R.,National Oceanic and Atmospheric Administration |
Franks J.S.,University of Southern Mississippi |
Driggers III W.B.,National Oceanic and Atmospheric Administration |
Howey P.W.,Microwave Telemetry Inc.
Bulletin of Marine Science | Year: 2013
Despite the circumglobal distribution of scalloped hammerheads, Sphyrna lewini (Griffith and Smith, 1834), little information is available regarding finescale movement and habitat use patterns for this species. Over a 27-d period, data were collected on diel habitat use and environmental preferences of a 240 cm (total length) female S. lewini. The shark exhibited a consistent and repeated diel vertical movement pattern, making more than 76 deep nighttime dives; the maximum depth reached was 964 m, where the temperature was 5.8 °C. The purpose of the nightly oscillatory deep diving pattern is unknown but could possibly represent feeding behavior. These findings represent the first detailed account of S. lewini diel vertical behavior and habitat utilization in the western North Atlantic Ocean. © 2013 Rosenstiel School of Marine & Atmospheric Science of the University of Miami.