Could there be a link between increased incidences of whale and dolphins with severe lesions and polluted marine environments?
A 7m humpback whale was recently disentangled (early July 2015) off the KwaZulu-Natal coast. It was found to be covered in skin lesions and from the air resembled an ‘ albino-look’.
This has concerned local marine ecologists and scientists as increased reports from other southern ocean countries (South America and Australia) reveal sores and cuts on whales researched in these areas.
Skin condition prevalence has been poorly studied in cetaceans and though not considered to cause the death of the animals it may be an indicator of other health problems or a polluted environment. A study a few years ago (by M.A. Faria and S. Rakotoharimalala) undertaken off the east coast of Madagascar on humpback whales revealed the following types of skin conditions:
– areas of hypo- or hyperpigmentation on any part of the body
– skin lesions which could be whitish and velvety, irregular and white or whitish rounded/ stippled lesions, granulomatous tissue, vesicular lesions and ulcerated lesions to name a few.
Researchers have found that 7 percent of coastal dolphins studied in Paracas Bay (Peru) had whitish, velvety lesions – this may be linked to polluted water close to the coastline.
In the case of the 7 m humpback the exact cause of the lesions is unknown and may be due to a virus or bacterial infection (Mike Meyer, Marine and Coastal Management South Africa). Tissue samples have been taken for RNA and DNA analysis.
The waters along and around the East London coast are heavily polluted from irregular discharges of sewage and un-treated pollutants (marine outfalls at Bat’s Cave and Hood Point are a point in case). To date no studies have been undertaken on the effects of pollution on our inshore dolphin species and on other marine mammals passing by.
Members of the public are encouraged not to touch stranded cetacean species unless protective gloves are worn. Bacterial/viral infections may arise from these contact sessions. Stranded dead whales with skin lesions are a health risk to humans if the meat is eaten.