LIVIVO - Search results -

Search results

Result 1 - 9 of total 9

Search options

Article ; Online: High bycatch rates of manta and devil rays in the “small-scale” artisanal fisheries of Sri Lanka

Daniel Fernando / Joshua D. Stewart

PeerJ, Vol 9, p e

2021 Volume 11994

Abstract: Background Expanding fisheries in developing nations like Sri Lanka have a significant impact on threatened marine species such as elasmobranchs. Manta and devil (mobulid) rays have some of the most conservative life history strategies of any ... ...

Abstract	Background Expanding fisheries in developing nations like Sri Lanka have a significant impact on threatened marine species such as elasmobranchs. Manta and devil (mobulid) rays have some of the most conservative life history strategies of any elasmobranch, and even low to moderate levels of bycatch from gillnet fisheries may lead to significant population declines. A lack of information on life history, demographics, population trends, and fisheries impacts hinders effective management measures for these species. Method We report on mobulid fishery landings over nine years between 2011 and 2020 across 38 landing sites in Sri Lanka. We collected data on catch numbers, body sizes, sex, and maturity status for five mobulid species. We used a Bayesian state-space model to estimate monthly country-wide catch rates and total annual landings of mobulid rays. We used catch curve analyses to estimate total mortality for Mobula mobular, and evaluated trends in recorded body sizes across the study period for M. mobular, M. birostris, M. tarapacana and M. thurstoni. Results We find that catch rates have declined an order of magnitude for all species across the study period, and that total annual captures of mobulid rays by the Sri Lankan artisanal fishing fleet exceed the estimated annual captures of mobulids in all global, industrial purse seine fisheries combined. Catch curve analyses suggest that M. mobular is being fished at rates far above the species’ intrinsic population growth rate, and the average sizes of all mobulids in the fishery except for M. birostris are declining. Collectively, these findings suggest overfishing of mobulid ray populations in the northern Indian Ocean by Sri Lankan artisanal fisheries. We recommend strengthening the management of these species through improved implementation of CITES, CMS, and regional fisheries management actions. In addition, we report on the demographic characteristics of mobulids landed in Sri Lanka and provide the first record of M. eregoodoo in the country.
Keywords	Mobula ; Small-scale fisheries ; Bycatch ; Age structure ; Size at maturity ; Medicine ; R ; Biology (General) ; QH301-705.5
Subject code	333
Language	English
Publishing date	2021-09-01T00:00:00Z
Publisher	PeerJ Inc.
Document type	Article ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

Full text online

Full text

Inter-library loan at ZB MED

Your chosen title can be delivered directly to ZB MED Cologne location if you are registered as a user at ZB MED Cologne.

Article ; Online: The impact of injury on apparent survival of whale sharks (Rhincodon typus) in South Ari Atoll Marine Protected Area, Maldives

Jessica Harvey-Carroll / Joshua D. Stewart / Daire Carroll / Basith Mohamed / Ibrahim Shameel / Irthisham H. Zareer / Gonzalo Araujo / Richard Rees

Scientific Reports, Vol 11, Iss 1, Pp 1-

2021 Volume 15

Abstract: Abstract The whale shark (Rhincodon typus) is an endangered species with a declining global population. The South Ari Atoll Marine Protected Area (SAMPA), Maldives, is one of few locations globally where year-long residency of individuals occurs. This ... ...

Abstract	Abstract The whale shark (Rhincodon typus) is an endangered species with a declining global population. The South Ari Atoll Marine Protected Area (SAMPA), Maldives, is one of few locations globally where year-long residency of individuals occurs. This SAMPA aggregation appears to consist almost exclusively of immature males. Due to its year-round residency, this local aggregation is subjected to a high degree of tourism pressure. This ecotourism contributes to the high level of interest and protection offered to whale sharks by the local community. Unfortunately, if regulations are not followed or enforced, tourism can bring with it major stressors, such as accidental injuries. We used POPAN capture-mark-recapture models and lagged identification rate analysis to assess the effect of major injuries on whale shark residency within SAMPA. Injuries may be obtained outside SAMPA. We found individuals with major injuries had a higher apparent survival in the area than those without. Lagged identification rates also demonstrated that sharks with major injuries are more likely to return to the area. We suggest that major injuries result in sharks prolonging their time in the developmental habitat. These findings have implications for individual fitness and the population viability of this endangered species. We propose targeted conservation strategies be considered to protect sharks from further injury. Based on the presented spatio-temporal distributions of sharks, and current local knowledge of sighting patterns, speed limit zones and propeller-exclusion zones should be implemented and enforced. If carried out alongside tourist education, these measures will contribute to the protection of whale sharks within SAMPA and beyond. Furthermore, our results can aid research direction, alongside regulation and enforcement development, at similar sites worldwide.
Keywords	Medicine ; R ; Science ; Q
Subject code	910
Language	English
Publishing date	2021-01-01T00:00:00Z
Publisher	Nature Portfolio
Document type	Article ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

Full text online

Full text

Inter-library loan at ZB MED

Your chosen title can be delivered directly to ZB MED Cologne location if you are registered as a user at ZB MED Cologne.

Article ; Online: Manta and devil ray aggregations

Marta D. Palacios / Joshua D. Stewart / Donald A. Croll / Melissa R. Cronin / Abel Trejo-Ramírez / Guy M. W. Stevens / Nerea Lezama-Ochoa / Kelly M. Zilliacus / Rogelio González−Armas / Giuseppe Notarbartolo di Sciara / Felipe Galván−Magaña

Frontiers in Marine Science, Vol

conservation challenges and developments in the field

2023 Volume 10

Abstract: Manta and devil rays (mobulids) are filter feeding elasmobranchs with extreme K-selective life histories found circumglobally from temperate to tropical waters. Their vulnerability to fisheries exploitation, bycatch, boat collisions, entanglement and ... ...

Abstract	Manta and devil rays (mobulids) are filter feeding elasmobranchs with extreme K-selective life histories found circumglobally from temperate to tropical waters. Their vulnerability to fisheries exploitation, bycatch, boat collisions, entanglement and unregulated tourism is exacerbated by their aggregative behavior. Studies have identified aggregation sites around the world for all nine mobulid species, with these groupings varying from a few individuals to thousands. However, the terminology used to define these aggregations and the drivers underpinning them remain unclear, hindering the development of effective management and conservation strategies. Here, we analyze aggregation behavior for mobulid species, providing consistent definitions for grouping events and summarizing the existing research on drivers and environmental factors triggering these events. We find that aggregation behaviors facilitate socializing and key life history functions in mobulids, including feeding, courtship and mating, predation avoidance, cleaning, and thermoregulation. Conservation threats and management mitigation opportunities associated with aggregations sites include fisheries, tourism, spatial protection, and climate change. Finally, we highlight knowledge gaps for future research prioritization and developments in the field for the identification of aggregation sites, the study of aggregation size and demographics and the functions and timing of aggregations.
Keywords	mobula ; grouping behavior ; elasmobranch ; social group ; management ; feeding ; Science ; Q ; General. Including nature conservation ; geographical distribution ; QH1-199.5
Subject code	333
Language	English
Publishing date	2023-04-01T00:00:00Z
Publisher	Frontiers Media S.A.
Document type	Article ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

Full text online

Full text

Inter-library loan at ZB MED

Your chosen title can be delivered directly to ZB MED Cologne location if you are registered as a user at ZB MED Cologne.

Article ; Online: Environmental characteristics associated with the presence of the Spinetail devil ray (Mobula mobular) in the eastern tropical Pacific.

Nerea Lezama-Ochoa / Martin A Hall / Maria Grazia Pennino / Joshua D Stewart / Jon López / Hilario Murua

PLoS ONE, Vol 14, Iss 8, p e

2019 Volume 0220854

Abstract: In the eastern Pacific Ocean, the tropical tuna purse-seine fishery incidentally captures high numbers of five mobulid bycatch species; all of which are classified as mortalities by the Inter-American Tropical Tuna Commission due to uncertainties in post- ...

Abstract	In the eastern Pacific Ocean, the tropical tuna purse-seine fishery incidentally captures high numbers of five mobulid bycatch species; all of which are classified as mortalities by the Inter-American Tropical Tuna Commission due to uncertainties in post-release mortality rates. To date, the factors (operational or environmental) leading to the capture of these species by the fishery have not been well studied. Here, we developed Generalized Additive Models for fisheries observer data to analyze the relationships between the presence/absence of Mobula mobular bycatch and oceanographic conditions, the spatial and temporal variability in fishing location, and the set type (associated with dolphins, free-swimming tuna schools or floating objects). Our results suggest that chlorophyll concentration and sea surface height are the most important variables to describe the presence of M. mobular in conjunction with geographic location (latitude and longitude) and set type. Presence of the species was predicted in waters with chlorophyll concentrations between 0.5-1 mg·m-3 and with sea surface height values close to 0; which indicates direct relationships with productive upwelling systems. Seasonally, M. mobular was observed more frequently during December-January and August-September. We also found the highest probability of presence observed in School sets, followed by Dolphin sets. Three areas were observed as important hotspots: the area close to the coastal upwelling of northern Peru, the area west to Islands Colon Archipelago (Galapagos) and the area close to the Costa Rica Dome. This information is crucial to identify the mobulids habitat and hotspots that could be managed and protected under dynamic spatial management measures to reduce the mortality of mobulid rays in the eastern Pacific purse-seine fishery and, hence, ensure the sustainability of the populations of these iconic species.
Keywords	Medicine ; R ; Science ; Q
Subject code	333 ; 551
Language	English
Publishing date	2019-01-01T00:00:00Z
Publisher	Public Library of Science (PLoS)
Document type	Article ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

Full text online

Full text

Inter-library loan at ZB MED

Your chosen title can be delivered directly to ZB MED Cologne location if you are registered as a user at ZB MED Cologne.

Article ; Online: Survival of the fattest

Joshua D. Stewart / John W. Durban / Holly Fearnbach / Lance G. Barrett‐Lennard / Paige K. Casler / Eric J. Ward / Derek R. Dapp

Ecosphere, Vol 12, Iss 8, Pp n/a-n/a (2021)

linking body condition to prey availability and survivorship of killer whales

2021

Abstract: Abstract Recovering small, endangered populations is challenging, especially if the drivers of declines are not well understood. While infrequent births and deaths may be important to the outlook of endangered populations, small sample sizes confound ... ...

Abstract	Abstract Recovering small, endangered populations is challenging, especially if the drivers of declines are not well understood. While infrequent births and deaths may be important to the outlook of endangered populations, small sample sizes confound studies seeking the mechanisms underlying demographic fluctuations. Individual metrics of health, such as nutritive condition, can provide a rich data source on population status and may translate into population trends. We examined interannual changes in body condition metrics of endangered Southern Resident killer whales (SRKW) collected using helicopters and remotely operated drones. We imaged and measured the condition of the majority of all three social pods (J, K, and L) in each of seven years between 2008 and 2019. We used Bayesian multi‐state transition models to identify relationships between body condition changes and both tributary‐specific and area‐based indices of Chinook salmon abundance, and K‐fold cross‐validation to compare the predictive power of candidate salmon covariates. We found that Fraser River (tributary‐specific) and Salish Sea (area‐based) Chinook salmon abundances had the greatest predictive power for J Pod body condition changes, as well as the strongest relationships between any salmon covariates and SRKW condition across pods. Puget Sound (tributary‐specific) Chinook salmon abundance had the greatest predictive power for L Pod body condition changes, but a weaker relationship than Fraser River or Salish Sea abundance had with J Pod body condition. The best‐fit model for K Pod included no Chinook covariates. In addition, we found elevated mortality probabilities in SRKW exhibiting poor body condition (reflecting depleted fat reserves), 2–3 times higher than whales in more robust condition. Collectively, these findings demonstrate that (1) fluctuations in SRKW body condition can in some cases be linked to Chinook salmon abundance; (2) the three SRKW pods appear to have distinct patterns of body condition fluctuations, suggesting ...
Keywords	adaptive management ; body condition ; drones ; foraging ecology ; multi‐state modeling ; Orcinus orca ; Ecology ; QH540-549.5
Language	English
Publishing date	2021-08-01T00:00:00Z
Publisher	Wiley
Document type	Article ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

Full text online

Full text

Inter-library loan at ZB MED

Your chosen title can be delivered directly to ZB MED Cologne location if you are registered as a user at ZB MED Cologne.

Article ; Online: The distribution of manta rays in the western North Atlantic Ocean off the eastern United States

Nicholas A. Farmer / Lance P. Garrison / Calusa Horn / Margaret Miller / Timothy Gowan / Robert D. Kenney / Michelle Vukovich / Julia Robinson Willmott / Jessica Pate / D. Harry Webb / Timothy J. Mullican / Joshua D. Stewart / Kim Bassos-Hull / Christian Jones / Delaney Adams / Nicole A. Pelletier / Jordan Waldron / Stephen Kajiura

Scientific Reports, Vol 12, Iss 1, Pp 1-

2022 Volume 20

Abstract: Abstract In 2018, the giant manta ray was listed as threatened under the U.S. Endangered Species Act. We integrated decades of sightings and survey effort data from multiple sources in a comprehensive species distribution modeling (SDM) framework to ... ...

Abstract	Abstract In 2018, the giant manta ray was listed as threatened under the U.S. Endangered Species Act. We integrated decades of sightings and survey effort data from multiple sources in a comprehensive species distribution modeling (SDM) framework to evaluate the distribution of giant manta rays off the eastern United States, including the Gulf of Mexico. Manta rays were most commonly detected at productive nearshore and shelf-edge upwelling zones at surface thermal frontal boundaries within a temperature range of approximately 20–30 °C. SDMs predicted highest nearshore occurrence off northeastern Florida during April, with the distribution extending northward along the shelf-edge as temperatures warm, leading to higher occurrences north of Cape Hatteras, North Carolina from June to October, and then south of Savannah, Georgia from November to March as temperatures cool. In the Gulf of Mexico, the highest nearshore occurrence was predicted around the Mississippi River delta from April to June and again from October to November. SDM predictions will allow resource managers to more effectively protect manta rays from fisheries bycatch, boat strikes, oil and gas activities, contaminants and pollutants, and other threats.
Keywords	Medicine ; R ; Science ; Q
Subject code	550
Language	English
Publishing date	2022-04-01T00:00:00Z
Publisher	Nature Portfolio
Document type	Article ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

Full text online

Full text

Inter-library loan at ZB MED

Your chosen title can be delivered directly to ZB MED Cologne location if you are registered as a user at ZB MED Cologne.

Article ; Online: Mobulid rays feed on euphausiids in the Bohol Sea

Christoph A. Rohner / Katherine B. Burgess / Joshua M. Rambahiniarison / Joshua D. Stewart / Alessandro Ponzo / Anthony J. Richardson

Royal Society Open Science, Vol 4, Iss

2017 Volume 5

Abstract: Mobulid rays have a conservative life history and are caught in direct fisheries and as by-catch. Their subsequent vulnerability to overexploitation has recently been recognized, but fisheries management can be ineffective if it ignores habitat and prey ... ...

Abstract	Mobulid rays have a conservative life history and are caught in direct fisheries and as by-catch. Their subsequent vulnerability to overexploitation has recently been recognized, but fisheries management can be ineffective if it ignores habitat and prey preferences and other trophic interactions of the target species. Here, we assessed the feeding ecology of four mobulids (Manta birostris, Mobula tarapacana, M. japanica, M. thurstoni) in the Bohol Sea, Philippines, using stomach contents analysis of fisheries specimens landed between November and May in 2013–2015. We show that the mobulids feed heavily on euphausiid krill while they are in the area for approximately six months of the year. We found almost no trophic separation among the mobulid species, with Euphausia diomedeae as the major prey item for all species, recorded in 81 of 89 total stomachs (91%). Mobula japanica and M. thurstoni almost exclusively had this krill in their stomach, while M. tarapacana had a squid and fish, and Ma. birostris had myctophid fishes and copepods in their stomachs in addition to E. diomedeae. This krill was larger than prey for other planktivorous elasmobranchs elsewhere and contributed a mean of 61 364 kcal per stomach (±105 032 kcal s.e., range = 0–631 167 kcal). Our results show that vertically migrating mesopelagic species can be an important food resource for large filter feeders living in tropical seas with oligotrophic surface waters. Given the conservative life history of mobulid rays, the identification of common foraging grounds that overlap with fishing activity could be used to inform future fishing effort.
Keywords	feeding ecology ; tropical zooplankton ; elasmobranchs ; mobulidae ; mesopelagic prey ; krill ; Science ; Q
Subject code	590
Language	English
Publishing date	2017-01-01T00:00:00Z
Publisher	The Royal Society
Document type	Article ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

Full text online

Full text

Inter-library loan at ZB MED

Your chosen title can be delivered directly to ZB MED Cologne location if you are registered as a user at ZB MED Cologne.

Article: Characterization of the trade in manta and devil ray gill plates in China and Southâeast Asia through trader surveys

O'Malley, Mary p / Kathy A. Townsend / Paul Hilton / Shawn Heinrichs / Joshua D. Stewart

Aquatic conservation. 2017 Apr., v. 27, no. 2

2017

Abstract: Dried gill plates from manta and devil rays, some of the world's most biologically vulnerable fishes, have become a valued commodity in Asian driedâseafood and traditional Chinese medicine markets. This trade is a primary driver of fisheries, which ... ...

Abstract	Dried gill plates from manta and devil rays, some of the world's most biologically vulnerable fishes, have become a valued commodity in Asian driedâseafood and traditional Chinese medicine markets. This trade is a primary driver of fisheries, which have led to declines in many mobulid populations. With no reliable trade statistics and scarce data on mobulid fisheries, this study estimates the number and species of mobulids required to supply this trade, and investigates the consumers and suppliers involved and drivers of demand. Following preliminary market research, 525 trader surveys were conducted in Hong Kong, Singapore, Macau, Taiwan, and southern China. Guangzhou, China was identified as the centre of the trade accounting for 99% of total estimated market volume of 60.5 tons of dried gill plates in 2011, increasing to 120.5 tons by 2013. The estimated number of mobulids converted from tons of gill plates more than doubled over the period to 130 000, comprising 96% devil rays, Mobula japanica, Mobula thurstoni, and Mobula tarapacana, and 4% Manta spp. By 2015 the Guangzhou market had declined sharply, reportedly due to conservation campaigns and government policies. However Hong Kong's gill plate sales increased dramatically between 2011 and 2015. China, Indonesia, Vietnam, Sri Lanka, and India were reported most frequently as gill plate sources. Vendors recommend gill plates (trade name pengyusai) for ailments ranging from acne to cancer and as a general health tonic. While pengyusai is a new addition to traditional Chinese medicine literature and is rarely prescribed by traditional medicine practitioners, it is readily available over the counter and aggressively marketed by vendors. Working in concert with consumer demand reduction efforts, increased measures to restrict mobulid fisheries and trade are recommended to prevent further population declines of these highly vulnerable species. Copyright Â© 2016 John Wiley & Sons, Ltd.
Keywords	Manta ; Mobula ; Oriental traditional medicine ; acne ; consumer demand ; fish ; fisheries ; market analysis ; markets ; neoplasms ; population dynamics ; sales ; surveys ; trade ; trade statistics ; vulnerable species ; China ; India ; Indonesia ; Macau ; Singapore ; Sri Lanka ; Taiwan ; Vietnam
Language	English
Dates of publication	2017-04
Size	p. 394-413.
Publishing place	John Wiley & Sons, Ltd
Document type	Article
Note	JOURNAL ARTICLE
ZDB-ID	1146285-1
ISSN	1052-7613
ISSN	1052-7613
DOI	10.1002/aqc.2670
Database	NAL-Catalogue (AGRICOLA)

Full text online

Accessible to users with ZB MED library card

In stock of ZB MED Bonn / Germany

Z 7590: Show issues

Order via subito

This service is chargeable due to the Delivery terms set by subito. Orders including an article and supplementary material will be classified as separate orders. In these cases, fees will be demanded for each order.

Inter-library loan at ZB MED

Your chosen title can be delivered directly to ZB MED Cologne location if you are registered as a user at ZB MED Cologne.

Details ▾

Article ; Online: Research Priorities to Support Effective Manta and Devil Ray Conservation

Joshua D. Stewart / Fabrice R. A. Jaine / Amelia J. Armstrong / Asia O. Armstrong / Michael B. Bennett / Katherine B. Burgess / Lydie I. E. Couturier / Donald A. Croll / Melissa R. Cronin / Mark H. Deakos / Christine L. Dudgeon / Daniel Fernando / Niv Froman / Elitza S. Germanov / Martin A. Hall / Silvia Hinojosa-Alvarez / Jane E. Hosegood / Tom Kashiwagi / Betty J. L. Laglbauer /

Nerea Lezama-Ochoa / Andrea D. Marshall / Frazer McGregor / Giuseppe Notarbartolo di Sciara / Marta D. Palacios / Lauren R. Peel / Anthony J. Richardson / Robert D. Rubin / Kathy A. Townsend / Stephanie K. Venables / Guy M. W. Stevens

Frontiers in Marine Science, Vol

2018 Volume 5

Abstract: Manta and devil rays are filter-feeding elasmobranchs that are found circumglobally in tropical and subtropical waters. Although relatively understudied for most of the Twentieth century, public awareness and scientific research on these species has ... ...

Abstract	Manta and devil rays are filter-feeding elasmobranchs that are found circumglobally in tropical and subtropical waters. Although relatively understudied for most of the Twentieth century, public awareness and scientific research on these species has increased dramatically in recent years. Much of this attention has been in response to targeted fisheries, international trade in mobulid products, and a growing concern over the fate of exploited populations. Despite progress in mobulid research, major knowledge gaps still exist, hindering the development of effective management and conservation strategies. We assembled 30 leaders and emerging experts in the fields of mobulid biology, ecology, and conservation to identify pressing knowledge gaps that must be filled to facilitate improved science-based management of these vulnerable species. We highlight focal research topics in the subject areas of taxonomy and diversity, life history, reproduction and nursery areas, population trends, bycatch and fisheries, spatial dynamics and movements, foraging and diving, pollution and contaminants, and sub-lethal impacts. Mobulid rays remain a poorly studied group, and therefore our list of important knowledge gaps is extensive. However, we hope that this identification of high priority knowledge gaps will stimulate and focus future mobulid research.
Keywords	manta ; mobula ; devil ray ; elasmobranch ; management ; Science ; Q ; General. Including nature conservation ; geographical distribution ; QH1-199.5
Subject code	333
Language	English
Publishing date	2018-09-01T00:00:00Z
Publisher	Frontiers Media S.A.
Document type	Article ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

Full text online

Full text

Inter-library loan at ZB MED

Your chosen title can be delivered directly to ZB MED Cologne location if you are registered as a user at ZB MED Cologne.

To top

Full text online

More links

Kategorien

Inter-library loan at ZB MED

Full text online

More links

Kategorien

Inter-library loan at ZB MED

Full text online

More links

Kategorien

Inter-library loan at ZB MED

Full text online

More links

Kategorien

Inter-library loan at ZB MED

Full text online

More links

Kategorien

Inter-library loan at ZB MED

Full text online

More links

Kategorien

Inter-library loan at ZB MED

Full text online

More links

Kategorien

Inter-library loan at ZB MED

Full text online

More links

Kategorien

In stock of ZB MED Bonn / Germany

Order via subito

Inter-library loan at ZB MED

Full text online

More links

Kategorien

Inter-library loan at ZB MED