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Age-Specific Survival and Reproductive Rates of Mediterranean Monk Seals at the Cabo Blanco Peninsula, West Africa

August 26, 2021

Live encounter data provides the first complete set of survival rate estimates for the Endangered Mediterranean monk seal birth into adulthood, as well as the first age-specific reproductive rates for the species.

We provide the first complete set of survival rate estimates for the Endangered Mediterranean monk seal Monachus monachus from 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.


de Larrinoa PF, Baker JD, Cedenilla MA, Harting AL, Haye MO, Muñoz M, Bareck HM, Bareck AM, Aparicio F, Centenera S, Gonzalez LM. 2021. Age-specific survival and reproductive rates of Mediterranean monk seals at the Cabo Blanco Peninsula, West Africa. Endangered Species Research. 45:315-29.  https://doi.org/10.3354/esr01134.

Last updated by Pacific Islands Fisheries Science Center on 11/23/2021