Distribution and length composition of lemon sharks (Negaprion brevirostris) in a nursery ground in southern Cuba

The protection of the habitats used by juvenile sharks is a management strategy that has recently caught the attention of fishery biologists. In the present study, we evaluated the population of the lemon shark (<em>Negaprion brevirostris</em>) from Los Roques Archipelago in order to identify the nursery area, describe the size composition, and examine the variation in nocturnal activity of the juvenile individuals. The data analysed came from three different sources: commercial shark fishery, tag-recapture sampling, and visual records. A total of 375 lemon sharks with total lengths between 55 and 281 cm were recorded during the study period. Overall data showed that the area occupied by juvenile lemon sharks was clearly partitioned into primary and secondary nurseries. Additionally, nighttime activity seemed to change according to the size of sharks in the primary nursery, suggesting a reduction of time activity overlapping among juveniles of distinct size/age. Results suggest that the strategy of utilization of the primary nurseries by the lemon shark may lead to important ecological benefits by reducing the competition, predation and natural mortality.

Download Full-text

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

Download Full-text

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.

Download Full-text

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.

Download Full-text

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.

Download Full-text