Seals Starving to Death

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By Petronella Sibeene WINDHOEK The mass mortalities and abortions of the Cape Fur seals along the Namibian coastline are a result of starvation due to scarcity of food, the Ministry of Fisheries and Marine Resources has confirmed. Since September 2006, dozens of adult seals have died and seal pups aborted along the coast north of Cape Cross. According to the Director of Resource Management in the ministry, Dr Moses Maurihungirire, based on the full examinations of a live adult Cape Fur seal and a dead pup carried out at a veterinary clinic, the stomach and alimentary tract were empty, with the abdominal kidney and heart fat depleted. The general condition for both animals was poor with the blubber (fat and oil) thickness in the adult less than one centimeter in width. The analysis of blood (histopathological) results indicated that there were no gross abnormalities of the organs. “The organs had no microscopic changes,” he said. Although the director could not indicate how many seals had died so far, he acknowledged that the starvation was a result of a lack of sufficient quantities of fish in the Namibian waters. Seals usually feed on pilchards and currently there is a scarcity of this resource for reasons not established yet. Although pilchards are preferred, they also eat squid and mackerel depending on what is available. Maurihungirire described the current lack of pilchards as terrible. “We have realized we have no pilchards but there is in (neighbouring) South Africa. Maybe they migrated,” he supposed. Some experts have attributed the lack of pilchards to the excessiveness of jellyfish, known to be culprits for swallowing pilchard eggs. Maurihungirire said the ministry is currently formulating proposals to assess the biomass of jellyfish and after that it will work on the way forward. Harvest time for seals starts in July and ends in November. At the beginning of this year’s season, there were about 980 000 adult seals. With the problem of insufficient food, the ministry will continue to sustainably manage the utilization of seals, Maurihungirire said. “We will keep appropriate numbers and ensure the eco-system is in balance,” he added. When seals were first reported to be dying in large numbers, the ministry was not certain whether this problem was a result of starvation or pathological viral infection. The high numbers of deaths and abortions are not unique as the same problem was experienced in 1988, 1989, 1994, 1995, 2000 and 2002. Fisheries Permanent Secretary Nangula Mbako two months ago said seal pups were not getting enough milk and that their chances of survival after weaning were almost zero. Monitoring by the ministry’s researchers shows that seal adult males and females were depicting reduced weight and that their condition was very poor. Scientific research has shown an increase in the Namibian seal population of more than 73 percent compared to the 1993 estimates and according to Mbako, the deaths imply that population numbers of these mammals have reached a stage where their current food source has become insufficient to sustain their livelihood. Various researches have also been done on the Namibian seal resource through routine pup ecological and population dynamic studies. These studies reveal that the 2006 winter pup growth rate declined from a long-term average of 30 g a day to 2 g a day at the southern colony of Wolf and Atlas Bay. Mbako reiterated that the poor growth rates in the south could be due to the fact that the pups are not getting enough milk from their mothers. It has also been found that 48 percent of males and 51 percent of females of the total pups at Wolf and Atlas Bay are below a threshold of post-weaning survival mass of 11 kg. At Cape Cross, only 12 percent of males and 11 percent of females are below the threshold.