Tag: mortality

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Monk seal death in Libya

Ibrahem Benamer, Natural Resources and Environmental Science,
Omar Mukhtar University (OMU), El-beida, Libya

On the 25 March in the area of Ain Gazzalla (Northeast Libya near the Egyptian border, 32.23284 N, 23.2848 E) a group of fishermen found a dead female monk seal trapped in their net. The case was reported to the coastguard who in turn informed the National Marine Laboratory. The carcass is now in their possession at the Lab and an autopsy is being arranged during this week.

This event is the only confirmed case of monk seal existence in eastern Libya since Norris 1972 [Norris, W.J.T. 1972. Monk Seals in Libya. Oryx 11: 328-330.], which may indicate that this critically endangered species can still be found in the area or close by, which will support the importance of the area as an MPA.

A report will be issued after the autopsy; meanwhile, pictures taken by the fishermen can be found on Flickr.

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Age study on Mediterranean monk seals

Recent Publications

Murphy S, Spradlin TR, Mackey B, McVee J and others. 2012. Age estimation, growth and age-related mortality of Mediterranean monk seals Monachus monachus. Endangered Species Research 16:149-163. [PDF 1.4]

ABSTRACT: Mediterranean monk seals Monachus monachus are classified as Critically Endangered on the IUCN Red List, with <600 individuals split into 3 isolated sub-populations, the largest in the eastern Mediterranean Sea. Canine teeth collected during the last 2 decades from 45 dead monk seals inhabiting Greek waters were processed for age estimation. Ages were best estimated by counting growth layer groups (GLGs) in the cementum adjacent to the root tip using unprocessed longitudinal or transverse sections (360 µm thickness) observed under polarized light. Decalcified and stained thin sections (8 to 23 µm) of both cementum and dentine were inferior to unprocessed sections. From analysing patterns of deposition in the cementum of known age-maturity class individuals, one GLG was found to be deposited annually in M. monachus. Ages ranged from 0.5 to 36 yr for females, 0.5 to 21 yr for males and 0.5 to 25.5 yr for individuals of unknown sex. The majority of seals (65%) were considered adults (≥4 yr), followed by juveniles (20%, <1 yr) and sub-adults (15%, 1−3.9 yr). Thirty percent of the aged sample had died from human-related causes, such as accidental entanglement in fishing gear and direct killings. A single-Gompertz growth curve was generated for both sexes using standard length data, resulting in asymptotic values of 212.3 cm for females and 221.8 cm for males. This study represents the first quantitative glimpse of sex-specific growth in monk seals and the age structure of dead individuals in this rare species’ core range.