Abstract
We provide the first complete set of survival rate estimates for the Endangered Mediterranean monk sealMonachus monachusfrom birth into adulthood, as well as the first age-specific reproductive rates for the species. From 2002 to 2016, we obtained individual seal live encounter data through non-invasive monitoring techniques that were analyzed to estimate vital rates of Mediterranean monk seals of the Cabo Blanco (Western Sahara/Mauritania) population. From birth to age 2 mo, when pups molt, survival averaged 0.59, ranging from 0.41 to 0.74 among cohorts. From birth to 1 yr and from 1 to 2 yr, median estimated survival rates were 0.46 and 0.75, respectively. Beyond 2 yr, survival estimates differed by sex: 0.94 for males and 0.97 for females. From 2005 to 2016, we estimated a mean gross reproductive rate of 0.71. The youngest parturient females were 3 yr old. Fitted age-specific reproductive rates increased beginning at age 3 yr and exceeded 0.80 from age 6 to 17 yr. Despite low survival during the first 2 mo of life, the aggregate vital rates of the population are favorable for growth; a Leslie matrix containing our survival and fecundity estimates yielded an intrinsic growth rate of 1.058. Increasing abundance and favorable vital rates are a testament to the efficacy of the many measures taken to promote the conservation of this population.
Highlights
Survival, fecundity, immigration, and emigration are the parameters that together determine population abundance over time
The Endangered Mediterranean monk seal Monachus monachus is the rarest species of pinniped; the most recent published assessment reports that fewer
Sex- and age-specific survival rates were calculated by dividing the randomized number of survivors to at least age 2 yr by the number known to have been alive at age 2 mo
Summary
Fecundity, immigration, and emigration are the parameters that together determine population abundance over time. The monk seal caves are situated just 7 km from Nouadhibou, a rapidly growing commercial center with a population of over 100 000 Both local artisanal and large-scale modern foreign fishing fleets operate in the waters adjacent to Cabo Blanco peninsula (Belhabib et al 2012). The perilous status of the Cabo Blanco monk of reproductive-age females used to estimate birth seal population following the 1997 mass mortality, rates. We analyzed more than a decade coupled with known negative impacts of human dis- of live encounter data to estimate vital rates of Mediturbance on the species throughout its range, terranean monk seals at Cabo Blanco, encompassing prompted the 2006 Action Plan to emphasize hands- a period of population increase and enhanced conoff methods. Tification techniques had already been developed for studying monk seals at Cabo Blanco prior to the mass mortality event (Forcada & Aguilar 2000), and were
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