Long-term migration patterns and bisexual philopatry in a benthic shark species

2017 ◽  
Vol 68 (8) ◽  
pp. 1414 ◽  
Author(s):  
Nathan Charles Bass ◽  
Johann Mourier ◽  
Nathan A. Knott ◽  
Joanna Day ◽  
Tristan Guttridge ◽  
...  
Keyword(s):  
Management Strategies ◽  
Movement Patterns ◽  
Conclusive Evidence ◽  
Migration Route ◽  
Shark Species ◽  
Apex Predators ◽  
Arrival Times ◽  
And Bisexual ◽  
Australian Coastline ◽  
Port Jackson

Knowledge of the broad-scale movement patterns of sharks is essential to developing effective management strategies. Currently there is a large bias in studies focusing on species that are either large apex predators or found in tropical to subtropical regions. There is limited knowledge of the movements and migrations of benthic and temperate shark species. The present study used passive acoustic telemetry to investigate the movement patterns of a benthic shark species, the Port Jackson shark (Heterodontus portusjacksoni). Individuals were tagged with acoustic transmitters between 2012 and 2014 and their movements were monitored within Jervis Bay and along the east Australian coastline for up to 4 years. Male and female Port Jackson sharks demonstrated high levels of philopatry to both Jervis Bay and their tagging location across multiple years. Although males and females did not differ in their arrival times, females departed from Jervis Bay later than males. Approximately half the tagged individuals migrated in a southward direction, with individuals being detected at Narooma, Bass Strait and Cape Barron Island. This study provides conclusive evidence of bisexual philopatry in a benthic temperate shark species, confirming previous hypotheses, and presents the most detailed migration route for Port Jackson sharks to date.

scholarly journals Impacts of Whale-Watching on the Short-Term Behavior of Fin Whales (Balaenoptera physalus) in a Marine Protected Area in the Southeastern Pacific

2021 ◽  
Vol 8 ◽  
Author(s):  
Macarena Santos-Carvallo ◽  
Fernanda Barilari ◽  
María José Pérez-Alvarez ◽  
Laura Gutiérrez ◽  
Guido Pavez ◽  
...  
Keyword(s):  
Marine Protected Area ◽  
Management Strategies ◽  
Movement Patterns ◽  
Economic Benefits ◽  
Observation Point ◽  
Behavioral Patterns ◽  
Whale Watching ◽  
Balaenoptera Physalus ◽  
Fin Whales ◽  
Response Variables

Whale-watching (WW) is an activity which has been increasing worldwide due to the great interest of tourists and the economic benefits it provides to local communities. However, it has been reported that this activity affects the behavioral patterns of some cetaceans, although for some species such as the fin whale (Balaenoptera physalus) this has not been extensively studied. To identify the effects of WW on the behavioral patterns of this species, we studied its traveling and resting behaviors in a locality of north-central Chile from 2015 to 2018. Using a theodolite, we calculated the response variables of swim speed, directness index, and reorientation for each behavior. We used the number of WW boats and the WW scenarios of “before”, “during”, and “after” the presence of boats as possible factors to explain the differences in the response variables of the whales, along with the factors of year, month, group size, and distance from the observation point. Reorientation increased significantly and the directness index decreased significantly for both traveling and resting behaviors from “before” to “during” WW scenarios, indicating more erratic and sinuous movements in the presence of boats. These changes in movement patterns are a commonly reported evasion response of cetaceans to the presence of WW boats. For traveling behavior, the swimming speed significantly increased, and trends showed increased reorientation and a decrease in the directness index in the “after” WW scenario, which suggests perturbation of the whales potentially associated with the speed and the direction in which the boats left. During resting behavior, the trajectories of the fin whales became straighter (decrease in reorientation) as the number of boats increased, thus evasion (more erratic and sinuous movements) is a behavior used less by fin whales as the number of boats increases. Notwithstanding the fact that tourism development in the study area is small in scale, we found that WW generates adverse effects that are reflected in changes in the whales’ movement patterns. This kind of information is valuable to the adjustment and/or design of management strategies for the species, which is fundamental for WW to continue to be a sustainable activity.

scholarly journals Antibiotic sensitivity of bacteria isolated from the oral cavities of live white sharks (Carcharodon carcharias) in South African waters

2019 ◽  
Vol 115 (11/12) ◽  
Author(s):  
Enrico Gennari ◽  
Alison A. Kock ◽  
Malcolm J. Smale ◽  
Alison Towner ◽  
Nasreen Khan ◽  
...  
Keyword(s):  
South Africa ◽  
Antibiotic Resistance ◽  
South African ◽  
Antibiotic Sensitivity ◽  
White Shark ◽  
Shark Species ◽  
Apex Predators ◽  
Carcharodon Carcharias ◽  
Bacterial Microbiota ◽  
Carbapenem Antibiotic

The white shark (Carcharodon carcharias) is responsible for 49% of shark-related injuries in South Africa, yet no information currently exists on the composition or antibiotic resistance of bacteria hosted by these apex predators in South African waters. This study aimed to address this gap by sampling the bacteria present in the oral cavities of 28 live C. carcharias along South Africa’s southern coastline. The antibiotic resistance of the range of microbiota was also assessed using antibiotic disc diffusion tests. A total of 51 strains from at least 20 species of bacteria were isolated from the oral cavities of C. carcharias. Of these strains, the most common bacteria present were Serratia spp., Proteus vulgaris and Vibrio alginolyticus. The overall antibiotic resistance was relatively higher in this study than that reported for bacterial microbiota sampled from other shark species. Results indicate that the combination therapy of imipenem (carbapenem antibiotic) and vancomycin (glycopeptide antibiotic) might be the most parsimonious option to effectively treat infections resulting from white shark bites, particularly in South Africa. It is hoped that, in addition to assisting medical professionals to treat shark bite victims, these findings enhance the understanding of the microbial communities present in large coastal predators and their surrounding environments.

Assessing growth band counts from vertebrae and dorsal-fin spines for ageing sharks: comparison of four methods applied to Heterodontus portusjacksoni

2009 ◽  
Vol 60 (9) ◽  
pp. 898 ◽  
Author(s):  
Javier Tovar-Ávila ◽  
Christopher Izzo ◽  
Terence I. Walker ◽  
J. Matías Braccini ◽  
Robert W. Day
Keyword(s):  
Shark Species ◽  
Systematic Bias ◽  
Age Validation ◽  
Growth Band ◽  
Dorsal Fin ◽  
Growth Bands ◽  
Visible Growth ◽  
Port Jackson ◽  
First Time ◽  
Fin Spines

Four methods for counting growth bands using vertebrae and dorsal-fin spines of the Port Jackson shark, Heterodontus portusjacksoni, are compared. Both calcified structures presented observable growth bands, allowing cross comparison among structures for the first time in a shark species. Whole and sectioned vertebrae and dorsal fin-spines possess highly visible growth bands and intra-reader band counts resulted in similar precision indices with little systematic bias. However, inter-reader growth band count plots showed possible biases in counts from sectioned vertebrae and sectioned dorsal-fin spines. Sectioned vertebrae and whole and sectioned dorsal-fin spines produced similar growth band counts, whereas whole vertebrae produced significantly lower counts. The similar readability, precision indices, growth band counts and apparent absence of biases between counts for a single reader would indicate that sectioned vertebrae and whole and sectioned dorsal-fin spines are both potentially useful and acceptable methods for band counting. However, inter-reader comparisons are necessary to avoid acceptance of biased estimations, resulting in over- or under-estimations of age. Validation for all age classes is essential to determining accurate age estimations for this and other species.

scholarly journals Density responses of lesser-studied carnivores to habitat and management strategies in southern Tanzania’s Ruaha-Rungwa landscape

PLoS ONE ◽  
2021 ◽  
Vol 16 (3) ◽  
pp. e0242293
Author(s):  
Marie Hardouin ◽  
Charlotte E. Searle ◽  
Paolo Strampelli ◽  
Josephine Smit ◽  
Amy Dickman ◽  
...  
Keyword(s):  
Wildlife Management ◽  
Management Strategies ◽  
Ecological Knowledge ◽  
Anthropogenic Pressure ◽  
Miombo Woodlands ◽  
Apex Predators ◽  
Miombo Woodland ◽  
Mixed Use ◽  
Management Area ◽  
By Catch

Compared to emblematic large carnivores, most species of the order Carnivora receive little conservation attention despite increasing anthropogenic pressure and poor understanding of their status across much of their range. We employed systematic camera trapping and spatially explicit capture-recapture modelling to estimate variation in population density of serval, striped hyaena and aardwolf across the mixed-use Ruaha-Rungwa landscape in southern Tanzania. We selected three sites representative of different habitat types, management strategies, and levels of anthropogenic pressure: Ruaha National Park’s core tourist area, dominated by Acacia-Commiphora bushlands and thickets; the Park’s miombo woodland; and the neighbouring community-run MBOMIPA Wildlife Management Area, also covered in Acacia-Commiphora. The Park’s miombo woodlands supported a higher serval density (5.56 [Standard Error = ±2.45] individuals per 100 km2) than either the core tourist area (3.45 [±1.04] individuals per 100 km2) or the Wildlife Management Area (2.08 [±0.74] individuals per 100 km2). Taken together, precipitation, the abundance of apex predators, and the level of anthropogenic pressure likely drive such variation. Striped hyaena were detected only in the Wildlife Management Area and at low density (1.36 [±0.50] individuals per 100 km2), potentially due to the location of the surveyed sites at the edge of the species’ global range, high densities of sympatric competitors, and anthropogenic edge effects. Finally, aardwolf were captured in both the Park’s core tourist area and the Wildlife Management Area, with a higher density in the Wildlife Management Area (13.25 [±2.48] versus 9.19 [±1.66] individuals per 100 km2), possibly as a result of lower intraguild predation and late fire outbreaks in the area surveyed. By shedding light on three understudied African carnivore species, this study highlights the importance of miombo woodland conservation and community-managed conservation, as well as the value of by-catch camera trap data to improve ecological knowledge of lesser-studied carnivores.

scholarly journals Effects of Tidally Varying River Flow on Entrainment of Juvenile Salmon into Sutter and Steamboat Sloughs

2020 ◽  
Vol 19 (2) ◽  
Author(s):  
Jason Romine ◽  
◽  
Russell Perry ◽  
Paul Stumpner ◽  
Aaron Blake ◽  
...  
Keyword(s):  
River Flow ◽  
Management Strategies ◽  
Tidal Flow ◽  
Potential Effect ◽  
Rate Of Change ◽  
Sacramento River ◽  
Juvenile Salmon ◽  
Migration Route ◽  
Management Actions ◽  
Hydrodynamic Data

Survival of juvenile salmonids in the Sacramento–San Joaquin Delta (Delta) varies by migration route, and thus the proportion of fish that use each route affects overall survival through the Delta. Understanding factors that drive routing at channel junctions along the Sacramento River is therefore critical to devising management strategies that maximize survival. Here, we examine entrainment of acoustically tagged juvenile Chinook Salmon into Sutter and Steamboat sloughs from the Sacramento River. Because these sloughs divert fish away from the downstream entrances of the Delta Cross Channel and Georgiana Slough (where fish access the low-survival region of the interior Delta), management actions to increase fish entrainment into Sutter and Steamboat sloughs are being investigated to increase through-Delta survival. Previous studies suggest that fish generally “go with the flow”—as net flow into a divergence increases, the proportion of fish that enter that divergence correspondingly increases. However, complex tidal hydrodynamics at sub-daily time-scales may be decoupled from net flow. Therefore, we modeled routing of acoustic tagged juvenile salmon as a function of tidally varying hydrodynamic data, which was collected using temporary gaging stations deployed between March and May of 2014. Our results indicate that discharge, the proportion of flow that entered the slough, and the rate of change of flow were good predictors of an individual’s probability of being entrained. In addition, interactions between discharge and the proportion of flow revealed a non-linear relationship between flow and entrainment probability. We found that the highest proportions of fish are likely to be entrained into Steamboat Slough and Sutter Slough on the ascending and descending limbs of the tidal cycle, when flow changes from positive to negative. Our findings characterize how patterns of entrainment vary with tidal flow fluctuations, providing information critical for understanding the potential effect of management actions (e.g., fish guidance structures) to modify routing probabilities at this location.

scholarly journals Combating Bisexual Erasure: The Correspondence of Implicit and Explicit Sexual Identity

2020 ◽  
Author(s):  
Teri Ann Kirby ◽  
Sally Merritt ◽  
Sarah Baillie ◽  
Lori Wu Malahy ◽  
Cheryl Kaiser
Keyword(s):  
Sexual Identity ◽  
Impression Management ◽  
Implicit Association Test ◽  
Management Strategies ◽  
Bisexual Men ◽  
Men And Women ◽  
Sexual Identities ◽  
And Bisexual ◽  
Implicit And Explicit ◽  
Insight Into

Both heterosexual and gay/lesbian individuals still question and erase bisexual identities. Skeptics contend that people adopt bisexual identities for strategic motivations, such as avoiding the stigma associated with identifying as gay or for attention-seeking purposes. Across two studies, self-identified gay (N = 168), straight (N = 237), and bisexual (N = 231) participants completed a sexual identity Implicit Association Test, a measure that can provide insight into automatic associations and lessen the influence of impression management strategies. All three groups displayed implicit sexual identities that were consistent with their self-ascribed identities. Gay men and lesbians implicitly identified as more gay and less bisexual than bisexual men and women, who in turn identified as less straight and more bisexual than straight men and women. These findings show that self-reported sexual identities converge with implicit identities and have implications for understanding the psychology of sexual orientation.

scholarly journals Gap analysis of acoustic tracking data reveals spatial and temporal segregation in sympatric reef sharks

2020 ◽  
Author(s):  
Michael J. Williamson ◽  
Emma J Tebbs ◽  
Terrence P Dawson ◽  
David J Curnick ◽  
Francesco Ferretti ◽  
...  
Keyword(s):  
Acoustic Telemetry ◽  
Gap Analysis ◽  
Movement Patterns ◽  
Battery Life ◽  
Shark Species ◽  
Tracking Data ◽  
Telemetry Data ◽  
Temporal Segregation ◽  
Differential Movement ◽  
Reef Sharks

Abstract Background There are now a wide array of field and laboratory techniques available for gaining insight into the movement and behaviour of sharks. Although acoustic telemetry may lack the fine-scale resolution of satellite telemetry, the low cost and longer battery life make it a powerful tool for investigating elasmobranch behaviour. Here, in the absence of satellite tracking data, we develop a novel approach to analysing acoustic telemetry data, using detection gaps to infer movement patterns to and from monitored reef habitats, to investigate spatial and temporal segregation between two sympatric shark species in a large remote MPA. Methods A total of 102 grey reef and 76 silvertip sharks were fitted with long-term acoustic transmitters and tracked inside a large acoustic array of reef-based receivers in the British Indian Ocean Territory MPA, between 2014 and 2018. From the resulting dataset (768,081 movements), movements between receivers and recursive loops to the same receiver were identified. Using the durations of inter-receiver movements (i.e. detection gaps), individual behaviours were classified into ‘restricted’ or ‘wider ranging’ movements. Drivers of these movements were identified using network analysis, generalised linear mixed models and multi-model inference starting from an a priori set of explanatory variables. Results In general, silvertip sharks were more likely to undertake ‘wider ranging’ movements than grey reef sharks. ‘Wider ranging’ movements were more common at night compared to during the day, and during the wet season compared to the dry season. In addition, the difference in ‘wider ranging’ movements between the two species increased at night. These results suggest spatial segregation and temporal segregation of movements between grey reef and silvertip sharks in the region. Conclusions We present a novel analysis of detection gaps from acoustic telemetry data to infer differential movement patterns and describe how species organise in space and time. Furthermore, this approach shows that acoustic telemetry gap analysis can be used for comparative studies, or combined, with other research techniques to better understand the functional role of sharks in reef ecosystems, moving towards more informed strategies for the conservation and management of the marine environment.

Nursery grounds, movement patterns and growth rates of dusky sharks, Carcharhinus obscurus: a long-term tag and release study in South African waters

2009 ◽  
Vol 60 (6) ◽  
pp. 571 ◽  
Author(s):  
Nigel E. Hussey ◽  
Ian D. McCarthy ◽  
Sheldon F. J. Dudley ◽  
Bruce Q. Mann
Keyword(s):  
South African ◽  
Growth Rates ◽  
Movement Patterns ◽  
Small Scale ◽  
Shark Species ◽  
Early Life Stages ◽  
Kwazulu Natal ◽  
Management Plans ◽  
Carcharhinus Obscurus

Knowledge of movement patterns of sharks in coastal waters is critical for the structuring of regional management plans. Through a long-term tag–recapture program, 9716 dusky sharks (Carcharhinus obscurus) were tagged and released along the east coast of South Africa. A total of 648 C. obscurus, principally small sharks (<100 cm PCL), were recaptured. Most recaptures were within 100 km of the tagging location in the nursery habitat in KwaZulu-Natal (KZN) with small scale movements occurring throughout the year. Forty-eight C. obscurus undertook movements >200 km that indicated a southerly migration between KZN and Eastern/Southern Cape (E/SC) between June and November. Seasonal northerly migrations were less well defined. The largest southerly and northerly movements were 1323 km and 1374 km, respectively. For sharks moving 1–100 km south from their tagging locality in KZN, an increase in displacement occurred between June and September identifying animals beginning their migration to the E/SC. With increasing displacement, there was also an increase in minimum swimming speed. Calculated growth rates of small sharks of 10.3–11.5 cm year–1 were in agreement with current literature values. Established tag–recapture programs provide an important tool in understanding the ecology of early life-stages of coastal shark species.

Residency, space use and movement patterns of juvenile sandbar sharks (Carcharhinus plumbeus) within a Virginia summer nursery area

2010 ◽  
Vol 61 (2) ◽  
pp. 223 ◽  
Author(s):  
C. L. Conrath ◽  
J. A. Musick
Keyword(s):  
Movement Patterns ◽  
Nursery Area ◽  
Small Scale ◽  
Shark Species ◽  
Eastern Shore ◽  
Carcharhinus Plumbeus ◽  
Near Shore ◽  
Passive Acoustic ◽  
Conservation And Management ◽  
Juvenile Sharks

Neonates and juveniles of many large coastal shark species occupy shallow inshore nursery areas during portions of the year. The identification of how these areas are used by large coastal shark populations is an important consideration in conservation and management efforts. An array of passive acoustic receivers was utilised to track the movements of 64 neonate and juvenile sandbar sharks within the Eastern Shore of Virginia summer nursery during the summers of 2003–2005. Residency patterns were variable during each year of the study, with younger sandbar sharks spending more time within the array area than older sharks. The number of detections was positively related to the distance of the receiver inshore from the inlet, indicating that young sandbar sharks preferentially utilise protected, shallow near-shore waters. Neonate and juvenile sandbar sharks tended to be detected more frequently within all areas of the inlet at slack tides, during the night and during early dawn hours. Periodogram analyses indicated that juvenile sharks tend to move in the direction of tidal currents. The present study documents large- and small-scale movement patterns of juvenile sandbar sharks and emphasises the importance of nursery-area habitats for this species.

scholarly journals Heat Tolerance, Energetics, and Thermal Treatments of Honeybees Parasitized With Varroa

2021 ◽  
Vol 9 ◽  
Author(s):  
Patricia Aldea-Sánchez ◽  
Guillermo E. Ramírez-Cáceres ◽  
Enrico L. Rezende ◽  
Francisco Bozinovic
Keyword(s):  
Energy Expenditure ◽  
Heat Tolerance ◽  
Synergistic Effects ◽  
Management Strategies ◽  
Conclusive Evidence ◽  
Adaptive Responses ◽  
Survival Times ◽  
Death Time ◽  
Fat Reserves ◽  
The Impact

Ongoing global change affects both wildlife and economically relevant species, which are now subjected to combined challenges from climate change and higher exposure to pathogens. Honeybee colonies worldwide are under threat by higher temperatures and the ectoparasitic mite Varroa destructor, hence we studied the impact of these combined challenges in the thermal biology and energetics of Apis mellifera. We estimated the heat tolerance and energy expenditure (CO2 production and VCO2) of honeybees acclimated to different temperatures (32 and 38°C) and subjected to different levels of parasitism (0, 1, and 2 mites). Heat tolerance was quantified employing thermal death time (TDT) curves describing how survival times vary as a function of temperature, which differed significantly between treatments. Warm-acclimated uninfected bees exhibited a higher thermal tolerance than their cold-acclimated counterparts, but parasitism by Varroa resulted in a substantial drop in tolerance rendering TDT curves of parasitized bees virtually indistinguishable. Accordingly, VCO2 increased dramatically in parasitized bees (46.5 and 67.1% with 1 and 2 Varroa, respectively), suggesting that Varroa impinges on substantial costs on energy expenditure which, in combination with lower fat reserves due to parasitism, should have synergistic effects on bees’ survival and performance. Results provide conclusive evidence of the detrimental impact of Varroa on heat tolerance that undermines potentially adaptive responses associated with thermal acclimation. Results also show that heat treatments are a realistic venue to control Varroa, and we discuss how TDT curves may be employed to optimize management strategies in this context.

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