Monk seal pup production in the Northern Sporades by MOm

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Contributionsto the Zoogeographyand Ecologyof the EasternMediterraneanRegion Vol. 1(1999),pp.413-419

MONK SEAL PUP PRODUCTION IN THE NATIONAL MARINE PARK OF ALONNISSOS N. SPORADES

P. DENDRINOS, S. KOTOMATAS & E. TOUNTA Abstract Since 1990,11long term project hasbeenestablishedin the NationalMarine Parkof Alonnissos-N. Sporadesandthe neighbouringareaswith aim to studyandmonitor th~statusof the local sealpopulation.Part of this project,from which resultsarepresented,wasto recordpup productionandpup behaviourin the wild. The studywasconductedby regulardirect visits to the sealhabitats(seacaves)andby the useof programmed photographiccameraswithin the shelters,throughwhich individualsobservedwereidentifiedandtheir behaviour was recorded.During the study period, from 1990until November1995,35 new born pupshavebeen recordedand monitoredwithin the study area.The births of pupsrecordedare distributedbetweenJuly and Decemberwith a peakin October. Morphometricdata on total length of pupsof one week old providedan averageof 104cm, whi1eaverageweight was measuredat 16 kg. The externalmorphologyof all the individuals were characterisedby a distinct light colour patchat the abdomenin contrastto the dark grey-blackcoloration on the rest of their thick pelage.Moulting period was observedto startthe earliestat an age5 weeks old and wasfound to last at least2 weeks.In termsof behaviour,during the first monthof development,pups were not found constantlyin the presenceof their mothers,while by the fourth month, pups were observed with their motherse"en lessfrequently.Pupswere seenenteringthe seawithin the cavesin the first weekof life even in the absenceof their mothers.Swimming and diving ability improvedwith age,and pups were found to changesheltersandtravel distancesof severalhundredmeters,evenat an early age. ll£QlA1),/,1)

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413

,INTRODUCTION The Mediterranean

monk seal (Monachus monachus) is considered to be a high-

ly endangered species and the number one endangered marine mammal in Europe (RONALD & DuGUY 1984). The former distribution of the Mediterranean monk seal extended from the Black Sea, through the Mediterranean

to the Atlantic

coast of North

Africa, at least, as far south as, the Cap Blanc peninsula in Mauritania. Presently, its distribution is extremely patchy and only fragmentary populations still exist. Its world population is estimated to be 400-550 individuals of which 200-250 individuals are estimated to live in Greece (REIJNDERSet ai. 1993). In Greece, seals are thought to exist in islands throughout the Aegean and Ionian seas (PANOU et ai. 199'3), but the best studied and possibly the largest population is found in the Northern Sporades island complex (HSSPMS 1995). The fact that the N. Sporades island complex, due to the existence of the monk seal population, have been officially declared a Special Area of Conservation, as a National Marine Park, in 1992 by a Presidential Decree, makes this one of the most important areas for the survival of tvis species. The fact that the Mediterranean monk seal is rare, is found in isolated rocky islands, spends considerable time underwater, and when on land seeks refuge in secluded coastal caves, the location and study of this species becomes logistically very difficult. This is-mainly the reason for the limited knowledge that currently exists relative to the species' distributi~n and habitat, the status of its local populations, the movements within and between populations, its ecological requirements and other basic biological parameters. Especially, relative to the biology of monk seal pups, most of the existing data are based on opportunistic encounters of researchers with pups (TROITZKY 1953, KING 1956, RONALD & HEALY 1974, SEARGENTet ai. 1978), or often parameters have been extrapolated from values known (KENYON & RICE 1959) for Monachus schaz,tinsiandi, the Hawaiian monk seal. Particular data on morphology, time of birth and behaviour of pups, have been presented by MURSALOGLOU(1984, 1986) and MARCHESSAUX& PERGENT-MARTINI (1991) froni work conducted in Turkey and Mauritania, respectively. Since the N. Sporades islands hold one of the largest breeding monk seal populations, provide the opportunity to collect in the field, valuable data on the species and especially on the biology and ecology of the pup stage. This study is part of a long-term programme in the N. Sporades, which was established in 1990, in order to monitor the status of the monk seal population of the area (HSSPMS 1995). The aim of the study was to record all births within the study area, to determine the distribution of births in time and space, and to collect data on the development and behaviour of monk seal pups during the first months of their life.

MATERIALS

AND METHODS

The study was conducted in the National Marine Park of Alonnissos - N. Sporades (NMPANS),

414

which has an area of 2200 square kilometres, and includes nine islands and

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a number of islets. Apart from the NMPANS, the study area included the neighbouring to the NMPANS areas of the islands, Agios Georgios, Skopelos and Dassia. The methodology used for monitoring the seal population consisted of a combination of two methods (HSSPMS 1995): A. The first method, which was used as the main study method, is based on direct observations within the 35 seal shelters of the study area. The team approachesthe shelters and depending on the cave enters each shelter with a small inflatable boat rowing or by snorkelling. All shelters are visited approximately once a month throughout the year, with increased frequency at about once a week during late summer to early winter. Using the minimal light source a team member checks the shelter for the presenceof any animal: AI. If no animal is found, any signs of previous seal presenceare recorded. These signs are: tracks of movement and hollows or depressions from animals laying on the beach surface, smell from the animal, faecal matter deposited on the beach or on the surfaces of the cave, any hair that has fallen from an animal, or any other evidence (saliva, blood, placenta, etc.). The date, time of visit, location, state of the shelter, and findings are noted. The duration -of the visit does not last more than a few minutes at most. A2. If an animal is found within the shelter, then all visible characteristics (size, developmental stage, coloration, external skin marks or scars, overall status of the animal, sex) are recorded. Depending on the specific circumstances of each case and when possible (e.g~animal sleeping), a photograph of the animal is taken for a permanent record of the encounter with the specific individual. It is important to mention that all the above process lasts less than 2 minutes. During encounters with pups, and only if the conditions are suitable (mother or any other adult is not within or around a shelter, pup is young in the sensethat it has not shed its lanugo (woolly coat), pup is not disturbed by the presence of the researchers),length and weight measurementsare taken by measuring tape and by a 50kg capacity spring scale with a net, respectively. The age of pups was estimated within weekly intervals, based on the time interval between the date of the first encounter with a pup and the date this shelter was last surveyed in conjunction with the external morphology (presence of umbilical cord, state of umbilicus and dentition) of the animals (unpublished data). The methodology used during this study had as central consideration to minimise disturbance to the monk seals in the process of collecting the necessarydata. Thus, at any time when the animals observed appearedto be disturbed by the presenceof the researcherswithin a shelter, the visit was terminated and the team left the area. B. The second method used selectively was based on the use of cave camera equipment (built and supplied as part of Contract No. ACE 6611/28 between the European Commission and the Institute Royal des Sciences Naturelles de Belgique), which were implemented in certain seal shelters within the project area. The camerasare programmed to take one shot at predetefplined time intervals within the cave; thus each film is recording the conditions within the cave at specific time instancesfor up to several days. During the visits described above, the cameras were installed and the set-up and films were inspected and collected in subsequent visits. After development, the films are inspected for evidence of seal use and animal presence. 415

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RESULTS AND DISCUSSION During the study period (1990-1995), in total 1670 visits to the seal shelters were conducted, during which in 160 cases a monk seal pup was observed. In addition, 115 films (36 exposures) were used in the programmed cameras, from which pups were recorded in 11 of them. Upon evaluation of all the data collected during the study period, 35 different pups have been identified who were all born within the study area. Two of the pups were found orphan and malnourished. by inhabitants of the study area, and were treated in the Seal Treatment and Rehabilitation Centrc of Alonnissos (HSSPMS 1994. 1996). Data from these animals were not included in this study. The distribution of the births of pups through the duration of the project, as well as, the effort invested in surveying the study area is shown in Fig.1. Pups were observed in 11 of the 35 shelters of the study area, while births were recorded in (j shelters, of which 5 are located within the core zone of the Park, at the island of Piperi. It is important to mention that during the study period, births were recorded every year in shelters located in the core zone, a-result that provides evidence for the importance of the island of Piperi as the most important habitat within the study area. Thus its strict protection may be considered as vital for the conservation of the local monk seal population. In 22 animals the sex was determined with 12 of them being males and 10 females. From tAe total number of individual pups recorded, 6 were found dead within their shelters at the first encounter (one of which was prematurely born) and one was found dead two weeks after its first encounter. In all these cases,autopsies were conduct~ ed. The results of the autopsies and of the samples analysesprovided evidence that in all the casesthe death was due to natural causes(HSSPMS 1994, 1996), a fact not previously recorded in the field. Externally, all the pups, during the first month of development, have their bodies covered by a thick woolly coat of approximately 2cm length. All the animals observed were characterised by a distinct white -yellowish colour patch in the abdomen, while the rest of the body was black or dark brown in colour. In several casesthe patch had distinct black or dark brown spots. These and the shape of the patch werc used in the identification of the different individuals. The average total length (nose to flippers), measured in individuals of 1 week of age was found to 104cm (S.D. = 11.48, n=8), while in individuals of 2-4 weeks old, was found to be 113cm (S.D. = 9.67, n=9). The average weight measured in pups of 1 week old was 16kg (S.D. = 1.82, n=5). The above figures are in general agreementwith the ones available from 11 monk seal pups from different areas within the species distribution (MARCHESSAUX& PERGENT-MARTINI1991).

The distribution of the births recorded within the time of year is shown in Fig.2. It appears that all births are distributed between July and December, with a peak in the number of births recorded, in the first half of October. Similar seasonality in pupping season has been reported by TROITZKY(1953), SEARGENT et at. (1978) and by MARCHESSAUX & PERGENT-MARnNI (1991). In contrast, BOULVA& CYRUS(1976) and GONzALEzet at. (1994) have recorded births of pups throughout the year in the monk seal population of 416

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NEWBORN PUPS OBSERVED IN NORTHERN SPORADES

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DISTRIBUTION

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417

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the Western Saharan-Mauritania area. During the development of the pups, observations on the postnatal moulting of 15 different individuals were conducted. Initiation of moulting was observed at an age of 5 weeks old in two pups, while the earliest completion of moulting was observed within the 8th week of a pup's development. This last individual exhibited also the shortest moulting period, lasting 2 weeks. In two more individuals, moulting period was observed from initiation to completion, and was recorded lasting approximately 3 weeks. The moulting process observed in this study is similar to the one described for the Hawaiian monk sear (KENYON& RICE 1959), but in that species its initiation and completion occurs earlier in the development of the pup. In terms of behaviour, contrary to past reports (ThOITZKY 1953, RONALD & HEALY 1974), pups were observed to enter the sea within the shelters during their first week of life, ~ven in the absencetheir mother, while pups where observed to leave their shelter and swim in the vicinity alone in the second week of life. Their swimming and diving skills, even though they appear limited in the first week, are progressively developed and by the age of one and a half month old they swim and dive with ease. MURSALOGLOU (1984, 1986) has reported simil~r behaviour for 2 pups observed in caves of the Turkish coast. In certain cases, pups were observed swimming outside their shelters with their mothers. During the study, 11 pups were found to have changed shelters during their development and travel distances of several hundred meters at the age of two or three months old. In one occasion, a pup during the second week of development was observed to have moved into an adjacent shelter covering a distance of at least 1,500 meters. In addition, mothers were not found to be continuously within the shelters, during the development of their pups. This is in contrast to the Hawaiian monk seal, where pups are always accompanied by their mothers until weaning (KENYON& RICE 1959). In fact, even during the first week of development, pups were found alone in 51% of the times observed (see also MURSALOGLOU 1984). By the second month of life, pups were observed with their mother even less frequently (33% of cases),while by the fourth month, in only 20% of the observations, they were found in the presence of their mother.

ACKNOWLEDGEMENTS We would like to thankthe InternationalFundfor Animal Welfarefor their donationof the research vessel"IFAW-ODYSSIA", Mr. A. Kottas,and Mr. N. Lambadarioufor their assistance in the field, the people of SteniVala, Alonnissosfor their hospitality and the GreekMinistries of Agriculture and Environment for their support.This project was partially funded by the EuropeanCommission,D.G. XI, ContractNo. 6610(90)9165and 4-3010(92)7829.

REFERENCES BOULVA J. & CYRUS J.L. 1976.The Mediterraneanmonk seal,Monachusmonachus,in NorthwestAfrica (Tunisiato Mauritania).Rapp. CommintoMe/: Medit. 23(8): 79. GONZALEZ L.M., GONZALEZ J.R., FELIX M.S., GRAU E., LOPEZ-JURADO L.F. & AGUILAR A.

418

. ~

.. ~

1994.Puppingseasonand annualproductivityof the monksealMonachusmonachus in "Cabo Blanco" peninsula (Western Sahara-Mauritania). EuropeanResearchon Cetaceans-8. Proceedings of the 8th annual conference of the European Cetacean Society, Montpellier, France, 2-5 March 1994. p.281-283. HSSPMS (Hellenic Society for the Study and protection of the Monk Seal) 1994.. Continuation of the Establishment of a Rescue Networkfor orphan, wounded and sick seals and gathering of seal observation from the whole of Greece - function of the seal treatment and rehabilitation center in Alonnissos. Final report for the European Commission Project 4-3010(92}7829, April 1992-Mar~h 1994, HSSPMS 1995. Continuation of the Monitoring of the Monk Seals in the National Marine Park of Northern

Sporades.FinalReportfor theEuropean Commission Project4-3010(92)7829. HSSPMS 1996. Monk Seal Conservation in Greece. Part 1. Coastal and 1sland Greece. Final Repon for the European Commission Project B4-3040/95/009/AO/D2.. ' KENYON K.W. & RICE D.W. 1959. Life history of the Hawaiian monk seal. Pacific Science 13: 215-252. KING J.D. 1956. The monk seals (Genus Monachus). Bulletin of the British Museum 3(5): 201-256. MARCHESSAUX D. & PERGENT-MARTINI C. 1991. Biologie de la reproduction et developpement des nouveaux nes chez Ie phoque moine Monachus monachus. Les Especes Marines a proteger en Metiterranee, GIS Posidonie publ., 1991,349-358. MURSALOGLOU Q" 1984. The survival of Mediterranean monk seal (Monachus monachus) pup on the Turkish coast. In: Ronald K. & Duguy R. (eds.), Les Phoques Moines - Monk Seals. Proceedings of the Second international Conference on the Mediterranean Monk Seal, La Rochelle, France, 5-6 Oct. 1984. Ann. Soc. Sci. nat. Charente-Maritime, Suppl.: 41-47. MURSALOGLOU B. 1986. Pup-mother-environment rel,ations in the Mediterranean monk seal, Monachus monachus,.(Hermarin, 17790}, on Turkish coasts. Commun. Fac. Sci. Univ. Ankara, Ser C. 5(4}: 1-8. PANOU A., JACOBS J. & PANOS D. 1993. The 'endangeredMediterranean monk seal Monachus monachus in the Ionian Sea, Greece. BioI. Cons. 64: 129-140. REIJNDERS P., BRASSEUR S., van der TORN J., van der WOLF P., BOYD I., HARWOOD J., LAVIGNE D. & LOWRY L. 1993. Seals, Fur Seals, Sea Lions and Walrus. Status Survey and Conservation Plan. IUCN/SSG Seal Specialist Group.

RONALDK. 29P.. & HEALY

P.J. 1974. The monk seal (Monachus .

monachus).

F.A.O./A.C.M.R.R./

MM/SC/36-

RONALD K. & DUGUY R. (eds.). 1984. Les Phoques Moines - Monk Seals. Proceedings of the Second international Conference on the Mediterranean Monk Seal, La Rochelle, France, 5-6 Oct. 1984. Ann. Soc. Sci...nat. Charente-Maritime, Suppl. SERGEANT D., RONALD K., BOULVA J. & BERKES F. 1978. The recent status of Monachus monachus the Mediterranean monk seal. In: Ronald K. & Duguy R. (eds.), 1979. The Mediterranean monk seal. Proceedings of the First International Conference, Rhodes, Greece, 2-5 May 1978. UNEP Technical Series I. Pergamon Press. TROITZKY A. 1953. Contribution a I'etude des Pinnipedes a propos de deux phoques de la Mediterranee ramenes de crisiere par S.A.S. Ie Prince Rainier III de Monaco. Bulletin de l'/stitut Oceanographique. 1032: 1-46.

MOm/Hellenic

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10682 Athens,

Greece

the Study and Protection

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Seal, 18 Solomou

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