Nursery area and size structure of the lemon shark population, Negaprion brevirostris (Poey, 1868), in Los Roques Archipelago National Park, Venezuela

AbstractCharacterization of essential habitat for sharks is a key requirement for effective conservation of shark populations. In Cuba, shark essential habitat is largely undocumented. Here we present the first study of a shark nursery area in Cuban waters, for the lemon shark. Nursery areas for lemon sharks are typically surrounded by mangroves and contain sandy substrate where the young can feed, grow, move, and eventually disperse from the area. We conducted our study in Cuba’s La Salina Wildlife Refuge during 2015–2019, to understand the role this refuge might play as a lemon shark nursery area, by documenting the distribution and length structure of juveniles. Our results indicate that juvenile lemon sharks are present throughout much of the refuge with no clear pattern of aggregation by size. The size range of all juveniles captured was 39.8–108.0 cm precaudal length (PCL) with a mode in length-class 70.0–75.0 cm PCL. The mean size and weight of all individuals during the study period was 75.8 cm PCL and 5.5 kg, respectively. We infrequently observed neonates in May, June, and September with size range 39.8–55.5 cm PCL. Enforcement of management regulations, difficult access to the refuge for fishers and other user groups, and isolation from human settlements are factors that help maintain nearly pristine conditions in La Salina Wildlife Refuge. The size/age structure of lemon sharks likely represents a population unaltered by human influence. We recommend our study be expanded to contribute to shark conservation and management as outlined in Cuba’s National Plan of Action for sharks.

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Fernando de Noronha as an insular nursery area for lemon sharks, Negaprion brevirostris, and nurse sharks, Ginglymostoma cirratum, in the equatorial western Atlantic Ocean

Marine Biodiversity Records ◽

10.1017/s1755267209000670 ◽

2009 ◽

Vol 2 ◽

Cited By ~ 17

Author(s):

Ricardo Clapis Garla ◽

José Garcia ◽

Leonardo Bertrand Veras ◽

Norberto Peporine Lopes

Keyword(s):

Atlantic Ocean ◽

Nursery Area ◽

Western Atlantic ◽

Negaprion Brevirostris ◽

Western Atlantic Ocean ◽

Lemon Sharks ◽

Ginglymostoma Cirratum ◽

Fernando De Noronha ◽

Nurse Sharks

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Hunting tactics of the lemon shark, Negaprion brevirostris, in shallow waters of an oceanic insular area in the western equatorial Atlantic

Neotropical Ichthyology ◽

10.1590/1982-0224-20160119 ◽

2017 ◽

Vol 15 (1) ◽

Cited By ~ 2

Author(s):

Ricardo C. Garla ◽

Otto B. F. Gadig ◽

José Garcia Junior ◽

Leonardo B. Veras ◽

Domingos Garrone-Neto

Keyword(s):

Surf Zone ◽

Sandy Beaches ◽

Shallow Waters ◽

Equatorial Atlantic ◽

Lemon Shark ◽

Negaprion Brevirostris ◽

Total Length ◽

Lemon Sharks ◽

Fernando De Noronha ◽

Hunting Tactics

ABSTRACT The hunting tactics of lemon sharks, Negaprion brevirostris, are described from underwater and cliff-top observations in the Fernando de Noronha Archipelago, western equatorial Atlantic, Brazil. Two main tactics were observed in the shallow waters of sandy beaches and reefs environments: (i) “substrate inspection” of crevices and holes over rocky and reef bottoms, and (ii) “sardine blitz”, which refer to striking schools of fishes (mainly sardines) in the surf zone. The first tactic was restricted to juveniles up to 2 m of total length, whereas subadult and adult sharks with total length larger than 2 m displayed the second. As lemon sharks use waters less than 5 m depth to hunt, perform social behaviours and predator avoidance, results highlight the importance of properly managing these habitats for their conservation, especially in areas where tourism has increased substantially.

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Modeling the population dynamics of lemon sharks

10.7287/peerj.preprints.364v1 ◽

2014 ◽

Author(s):

Easton R White ◽

John D Nagy ◽

Samuel H Gruber

Keyword(s):

Time Series ◽

Population Dynamics ◽

Age Structure ◽

Population Fluctuations ◽

Lemon Shark ◽

Demographic Stochasticity ◽

Negaprion Brevirostris ◽

Lemon Sharks ◽

Long Time ◽

Structure Density

Long-lived marine megavertebrates (e.g. sharks, turtles, mammals, and seabirds) are inherently vulnerable to anthropogenic mortality. Although some mathematical models have been applied successfully to manage these animals, more detailed treatments are often needed to assess potential drivers of population dynamics. In particular, factors such as age-structure, density-dependent feedbacks on reproduction, and demographic stochasticity are important for understanding population trends, but are often difficult to assess. Lemon sharks (Negaprion brevirostris) have a pelagic adult phase that makes them logistically difficult to study. However, juveniles use coastal nursery areas where their densities can be high. Thus, we use a stage-structured, Markov-chain stochastic model to describe lemon shark population dynamics from a 17-year longitudinal dataset at a coastal nursery area at Bimini, Bahamas. We found that the interaction between delayed breeding and demographic stochasticity accounts for 33 to 49% of the variance. Demographic stochasticity contributed all random effects in this model, suggesting that the existence of unmodeled environmental factors may be driving the majority of interannual population fluctuations. In addition, we are able to use our model to estimate the natural mortality rate of older age classes of lemon sharks that are difficult to study. Further, we use our model to examine what effect the length of a time series plays on deciphering ecological patterns. We find that — even with a relatively long time series — our sampling still misses important rare events. Our approach can be used more broadly to infer population dynamics of other large vertebrates in which age structure and demographic stochasticity are important.

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Modeling the population dynamics of lemon sharks

10.7287/peerj.preprints.364 ◽

2014 ◽

Author(s):

Easton R White ◽

John D Nagy ◽

Samuel H Gruber

Keyword(s):

Time Series ◽

Population Dynamics ◽

Age Structure ◽

Population Fluctuations ◽

Lemon Shark ◽

Demographic Stochasticity ◽

Negaprion Brevirostris ◽

Lemon Sharks ◽

Long Time ◽

Structure Density

Long-lived marine megavertebrates (e.g. sharks, turtles, mammals, and seabirds) are inherently vulnerable to anthropogenic mortality. Although some mathematical models have been applied successfully to manage these animals, more detailed treatments are often needed to assess potential drivers of population dynamics. In particular, factors such as age-structure, density-dependent feedbacks on reproduction, and demographic stochasticity are important for understanding population trends, but are often difficult to assess. Lemon sharks (Negaprion brevirostris) have a pelagic adult phase that makes them logistically difficult to study. However, juveniles use coastal nursery areas where their densities can be high. Thus, we use a stage-structured, Markov-chain stochastic model to describe lemon shark population dynamics from a 17-year longitudinal dataset at a coastal nursery area at Bimini, Bahamas. We found that the interaction between delayed breeding and demographic stochasticity accounts for 33 to 49% of the variance. Demographic stochasticity contributed all random effects in this model, suggesting that the existence of unmodeled environmental factors may be driving the majority of interannual population fluctuations. In addition, we are able to use our model to estimate the natural mortality rate of older age classes of lemon sharks that are difficult to study. Further, we use our model to examine what effect the length of a time series plays on deciphering ecological patterns. We find that — even with a relatively long time series — our sampling still misses important rare events. Our approach can be used more broadly to infer population dynamics of other large vertebrates in which age structure and demographic stochasticity are important.

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ANALYSIS OF THE MODERN GRAIN-SIZE COMPOSITION VARIABILITY OF THE ANAPA BAY-BAR BEACH SEDIMENTS

Materials of XXIV International Coastal Conference, devoted to the 60th anniversary of the “Sea Coasts” Working Group of RAS Council SEA COASTS – EVOLUTION, ECOLOGY, ECONOMY ◽

10.31519/conferencearticle_5b5ce3cd694162.92112428 ◽

2018 ◽

Author(s):

В. Крыленко ◽

V. Krylenko ◽

Р. Косьян ◽

R. Kos'yan ◽

М. Крыленко ◽

...

Keyword(s):

Grain Size ◽

Bottom Sediments ◽

Size Structure ◽

Size Composition ◽

Potential Danger ◽

Grain Size Composition ◽

Beach Sediments ◽

Sediment Particles ◽

Sand Material

The results of realized in 2010 field researches of the spatial and time grain-size structure variability of beach and bottom sediments of the bay-bar Anapskaya southern part are presented in this paper. Irretrievable carrying out of sediment particles to depths more than 7 m intensifies with their size decrease to 0,1 mm. As over 70 % bottom and about 60 % beach sediments are presented by fractions less 0,16 mm on bay-bar Anapskaya southern part, namely at this part there is sand material massive carrying out to depth. Potential danger of the investigated site geosystem degradation is revealed.

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Homing ability of young lemon sharks, Negaprion brevirostris

Environmental Biology of Fishes ◽

10.1007/s10641-004-2583-4 ◽

2005 ◽

Vol 72 (3) ◽

pp. 267-281 ◽

Cited By ~ 34

Author(s):

Susi Manuela Clermont Edr�n ◽

Samuel H. Gruber

Keyword(s):

Negaprion Brevirostris ◽

Lemon Sharks

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Shifts in plankton size spectra modulate growth and coexistence of anchovy and sardine in upwelling systems

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/cjfas-2015-0181 ◽

2016 ◽

Vol 73 (4) ◽

pp. 611-621 ◽

Cited By ~ 5

Author(s):

T. Mariella Canales ◽

Richard Law ◽

Julia L. Blanchard

Keyword(s):

Size Structure ◽

Prey Availability ◽

Empirical Work ◽

Size Composition ◽

Size Spectrum ◽

Small Particles ◽

Size Spectra ◽

Factors Influencing ◽

Spectrum Model ◽

Model Scenarios

Fluctuations in the abundance of anchovy (Engraulis spp.) and sardine (Sardinops sagax) are widespread in marine ecosystems, but the causes still remain uncertain. Differences between the planktonic prey availability, selectivity, and predation between anchovy and sardine have been suggested as factors influencing their dynamics. Using a dynamical multispecies size-spectrum model, we explore the consequences of changes in plankton size composition, together with intraguild predation and cannibalism, on the coexistence of these species. The shift towards smaller plankton has led to a reduction in the growth rate of both species. The effect was more deleterious on anchovy growth because it is unable to filter small particles. In model scenarios that included the effects of cannibalism and predation, anchovy typically collapsed under conditions favouring smaller sized plankton. The two species coexisted under conditions of larger sized plankton, although strong predation in conjunction with weak cannibalism led to the loss of sardine. The model provides new testable predictions for the consequences of plankton size structure on anchovy and sardine fluctuations. Further empirical work is needed to test these predictions in the context of climate change.

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