TY - JOUR
UR - https://doi.org/10.7287/peerj.preprints.364v1
DO - 10.7287/peerj.preprints.364v1
TI - Modeling the population dynamics of lemon sharks
AU - White,Easton R
AU - Nagy,John D
AU - Gruber,Samuel H
DA - 2014/04/15
PY - 2014
KW - demography
KW - density-dependence
KW - elasmobranch
KW - stage-based
KW - inverse modeling
KW - population dynamics
KW - stochasticity
KW - Negaprion brevirostris
AB -
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.
VL - 2
SP - e364v1
T2 - PeerJ PrePrints
JO - PeerJ PrePrints
J2 - PeerJ PrePrints
SN - 2167-9843
ER -