5 research outputs found
Three months journeying of a Hawaiian monk seal
Hawaiian monk seals (Monachus schauinslandi) are endemic to the Hawaiian
Islands and are the most endangered species of marine mammal that lives
entirely within the jurisdiction of the United States. The species numbers
around 1300 and has been declining owing, among other things, to poor juvenile
survival which is evidently related to poor foraging success. Consequently,
data have been collected recently on the foraging habitats, movements, and
behaviors of monk seals throughout the Northwestern and main Hawaiian Islands.
Our work here is directed to exploring a data set located in a relatively
shallow offshore submerged bank (Penguin Bank) in our search of a model for a
seal's journey. The work ends by fitting a stochastic differential equation
(SDE) that mimics some aspects of the behavior of seals by working with
location data collected for one seal. The SDE is found by developing a time
varying potential function with two points of attraction. The times of location
are irregularly spaced and not close together geographically, leading to some
difficulties of interpretation. Synthetic plots generated using the model are
employed to assess its reasonableness spatially and temporally. One aspect is
that the animal stays mainly southwest of Molokai. The work led to the
estimation of the lengths and locations of the seal's foraging trips.Comment: Published in at http://dx.doi.org/10.1214/193940307000000473 the IMS
Collections (http://www.imstat.org/publications/imscollections.htm) by the
Institute of Mathematical Statistics (http://www.imstat.org
Estimating the carrying capacity of French Frigate Shoals for the endangered Hawaiian monk seal using Ecopath with Ecosim
The carrying capacity of the French Frigate Shoals (FFS) region for the endangered Hawaiian monk seal was appraised using an updated version of the original FFS Ecopath model (Polovina 1984). Model parameters were updated using recent literature, and data from surveys of the seal population and its bottom-associated prey. Together they produced a static mass balance model for 1998 when the prey surveys began. The Ecopath-estimated monk seal biomass was 0.0045 t/km2, which was in close agreement with the biomass calculated from monk seal field beach counts (0.0046 t/km2). Model simulations through time were done in Ecosim using the Ecopath balanced model and included fisheries data time series from 1998 to 2008. Monk seal biomass declined concurrently with decreases in benthic bottomfish biomass, which were influenced by large-scale changes in the environment of the North Pacific. This model scenario was extended from 2010, when the last permitted fishery in the Northwestern Hawaiian Islands was closed, through to 2040, assuming a constant environmental signal. Model results for this time period did not show a recovery of monk seals that exceeded the initial 1998 model biomass levels, highlighting the importance of including environmental variability in estimates of monk seals recovery at FFS
Supplemental Information from Model recommendations meet management reality: implementation and evaluation of a network-informed vaccination effort for endangered Hawaiian monk seals
Supplemental data and analyses to support the paper