Date: Fri, 18 Jul 1997 19:22:38 +0000
From: alexa@porthos.bio.ub.es
Subject: Update monk seal die-off
The die-off that has been affecting the Cap Blanc population of
monk seals since mid- May is still producing deaths in the colony
although the current levels of mortality appear to be lower. During
the second half of June almost no casualties were observed, but
since July 5 two freshly dead individuals and three moribunds
have been detected.
Since the beginning of the event a total of 108 corpses have been
examined. However, the mortality is thought to have affected a
larger number of individuals. From standardized counts made on
the caves and their comparison with comparable counts made the
four previous years, it can be calculated that 68% of the population
has already disappeared. Thus, the colony, estimated to be originally
composed of about 300 seals, is thought to have been reduced now
to less than 100 individuals. 98% of the examined corpses were
adults and subadults, and 56% of the sexed individuals were males
and 44% females. Only 2 juveniles and 2 newborn pups have been
found. However, it is likely that the pups indeed died because
of malnutrition caused by the death of their mothers and not by
the direct effect of the agent causative of the mortality.
The four orphaned pups that were rescued by the LIFE-CE team at
the beginning of the event continue to be rehabilitated, and the
one that remained with its mother inside the caves has already
moulted and is in good condition. Another female gave birth on
20 June and is also apparently doing well in the caves.
Since the beginning, research to identify the causative agent
of the die-off has focused on two main potential agents: a virus
and a saxitoxin produced by a dynoflagellate.
Regarding the virological analysis, Dr. S. Kennedy (Northern Ireland
Agriculture Department, Stormont) has finalised the examination
of 10 seals and concluded that there were no indications of viral
infection. Only in one individual he find unidentified structures
that could either be the result of autolysis or a virus. Tests
for morbillivirus infection (IPX staining and PCR) all resulted
negative. The histological examination of lung sections showed
no evidence of a pneumonic process, as is commonly observed in
morbillivirus infection, in any animal. No results on the virological
analysis have been so far produced by Dr. A. Osterhaus (Erasmus
University, the Netherlands).
Regarding saxitoxins, the bioassay and HPLC analysis of tissues
from further seals and from a variety of fishes and filtrating
organisms have been completed by the three Spanish laboratories
involved (Dr. J. Franco from the Institute of Oceanographic Sciences;
Dr. E. Costas from the University of Madrid, and Dr. M. Fern=E1ndez
from the Community Laboratory on Biotoxins of Vigo). The results
from all laboratories have been coincidental in consistently detecting
the presence of at least two PSP saxitoxins in the tissues of
the seals and in some of the other organisms analysed, particularly
in the viscera of phytophagous fishes. Further, sea water examination
and cultures carried out by the two former laboratories have consistently
shown the presence of toxic dynoflagellates, particularly Alexandrium
minutum. Concentrations in seal tissues were, however, low and
a cause-effect relationship could not be indisputably established
from only the HPLC and bioassay tests. However, Dr. E. Costas
has recently applied immunofluorescence techniques to brain tissues
of four freshly dead seals and has detected the presence of saxitoxins
in all cases. The saxitoxin concentrations found in the brain
are associated to brain neuronal disruption capable to produce
the death of the seals, therefore producing evidence of the cause
of death. A recent message authored by Mr Taleb, director of the
Mauritanian Center for Fisheries Research (CNROP), and circulated
by the Seal Rescue and Research Center of Pieterburen (SRRC) in
MARMAM, has created considerable confusion when informing that
the CNROP had sent samples to some of the above laboratories and
that the results of the saxitoxin analyses on these samples were
negative. The three laboratories have, however, informed that
they never received any sample from the CNROP nor have ever sent
any report to Mr. Taleb, for which reason this information should
be considered incorrect.
Overall, the analytical results, the mortality pattern (only affecting
adults and with almost absent juvenile mortality) and the clinic
diagnosis (paralytic symptoms before death, lung congestion but
not pneumonic process), all point out that the cause of the die-off
is a saxitoxin of algal origin.
The Emergency Action Plan designed by a Committee of Experts that
met in the Amsterdam airport at the end of May was approved by
all its members with the exception of the representative of the
CNROP. The Plan has received a wide support from international
organizations (IUCN, WWF, UNEP, IFAW, Bonn Convention, European
Nature Heritage Fund, etc) and has also been approved by the Governor
of Nouadhibou and the Parc National du Banc d'Arguin (PNBA), the
Mauritanian national authority for nature conservation. Funding
for the implementation of the Plan has been offered by a number
of international organisations. The field team undertaking the
Plan is multidisciplinary and multinational, and it is mainly
composed of personnel from the University of Barcelona, the University
of Las Palmas, the Spanish Ministry of the Environment (all working
within the LIFE-CE framework), the Norfolk Wildlife Hospital,
the Sea Mammal Research Unit, and the Parc National du Banc d'Arguin.
It is soon expected the incorporation to the fieldwork of Greek
and Turkish researchers on monk seals.
Monitoring of the situation in the caves occupied by the colony
and in the surrounding cliffs and beaches has been maintained
constant since the beginning of the event by the LIFE-CE team
to assess trends in mortality and in population numbers. Necropsies
have been performed in over 70 individuals, with detailed sampling
in those corpses found fresh. Samples of blood have been obtained
from 6 apparently non-diseased seals and analyses carried out
on them did not indicate presence of infection or other disease.
Capture techniques, both for seals hauled-out on beaches or swimming
freely in open waters, have been adapted to the local conditions
and the appropriate equipment is now available on the spot. However,
until present, treatment of the diseased seals has unfortunately
only been possible inside the caves. This represents definite
physical risks to the personnel involved and produces sensible
disruption to the non-diseased individuals.
One of the main objectives of the Emergency Action Plan was the
closing of a cave or the construction of an enclosure in the neighbourhood
of the caves to temporarily keep seals in captivity. In this way
it was expected that the monitoring of the health status of the
seals and their safe treatment would be facilitated while avoiding
impact on the colony. Nevertheless, attempts to undertake such
action have been frustrated to date. The CNROP and its advising
institution, the Seal Research and Rescue Center of Pieterburen
(SRRC), opposed belligerently to the Action Plan, even when Peter
Reijnders, as supervisor of the Plan, travelled to Mauritania
to explain its details and urgency of implementation. The situation
appeared to be solved when on June 15 the Governor of Nouadhibou
informed Dr. Reijnders and the PNBA that the CNROP had changed
its position and was willing to participate in the implementation
of the Plan. Consequently, a formal letter of invitation to participate
in the seal rescue tasks was issued to the CNROP through the Governor.
Nevertheless, the CNROP never answered this invitation and continued
trying to obstruct the Plan.
As a consequence of this opposition, the permission from some
of the Mauritanian authorities to carry out these actions has
not yet been obtained. The reasons for such opposition to an otherwise
widely accepted Action Plan are unclear but do not appear to be
scientifically based. In the recent MARMAM message above mentioned,
as well as in a number of public declarations, the CNROP director
has stated that the disagreement was based on their assumption
that the mortality stopped by the end of May (at that time the
total number of corpses found was only 67, while today 108 have
already been recorded), and that the die-off was of viral origin
(an assumption not supported by analytical results and that was,
nevertheless, of no significance because the Committee of Experts
agreed that the Action Plan should be implemented irrespective
of the cause of the die-off).
Whatever are the reasons, the CNROP-SSRC opposition to the Emergency
Action Plan has prevented the field team to treat the seals, in
particular using the antidote against saxitoxins made available
by the US Marine Mammal Commission already by the end of May.
This has undoubtly had negative consequences on the successful
rescue of the diseased seals as well on the research towards the
clarification of the causes of the die- off. It is uncertain how
many seals could have been saved if the Plan had been implemented
more rapidly and efficiently, but it is clear that the contribution
of both the CNROP and the SRRC to the conservation of this, the
last colony of monk seals, has been profoundly negative.
Furthermore, the Emergency Action Plan also considered vaccinating
seals against morbillivirus as a preventive measure in the case
that the virus appeared in the future. The field team implementing
the Action Plan requested on 2 June the vaccines to the personnel
of the SSRC in Mauritania. Subsequent requests were made in numerous
occasions, two of them by writing (10 June and 10 July). However,
the vaccines have not been supplied to the field team to date
despite being available in Mauritania since the beginning of the
process.
Despite the low current levels of mortality, efforts to monitor
both live individuals and the appearance of newly dead seals,
as well as the undertaking of necropsies and attempts to rescue
diseased seals will continue. Material and personnel is ready
to build an interim enclosure in only about three days if the
authorisation is finally granted. The field team working for the
Emergency Action Plan is currently composed of 12 persons, mainly
from the University of Barcelona, the University of las Palmas
and the Norfolk Wildlife Hospital. It is considered that, given
the reduced current population levels, even a small number of
deaths may further compromise the future of the colony. Moreover,
the mortality has appeared to slow down in a couple of occasions
(end of May and second half of June) to re-start again, for which
reason the rescue operative will be maintained until the process
is definitely over.
Alex Aguilar (alexa@porthos.bio.ub.es)
Coordinator of the Emergency Action Plan
15 July, 1997