24 November 2021: New Article on the Health Status of By-Caught Harbour Porpoises

Kathrine Ryeng, chair of NAMMCO’s Committee on Hunting Methods, is the primary author of a new study that focused on the health status of by-caught harbour porpoises and was recently published in the scholarly journal Polar Biology. The article provides valuable information on this little-studied topic, revealing that the harbour porpoises accidentally taken in Norwegian Arctic waters had a relatively healthy status previous to their capture. 

The study reports the pathological findings in harbour porpoises by-caught in gillnet fisheries along the northern coastline of Norway. The harbour porpoises studied presented no evidence of severe disease. The most common pathological findings in the Arctic bycaught porpoises were parasitoses, found in multiple organs (lungs, liver, stomachs). For instance, pulmonary nematodiasis was found in 77 percent of the animals studied, which is consistent to prior findings. The severity of the infection, on the other hand, was noticeably different, with far more severe cases than previously recorded. Differences in the diet and age of the bycaught harbour porpoises are likely to be the cause of the health disparities observed in the various studies conducted in European and North Atlantic waters. 

Even though the vast majority of the porpoises had parasites in their stomachs, lungs and/or intestines, the animals tolerated the parasites without significant health problems. Besides, the study reveals that the animals had a good nutritional status and had been foraging recently. This finding, consistent with the previous studies conducted in Norwegian and Icelandic waters, confirms the relatively good health of the harbour porpoises in Norwegian Arctic waters. 

The full study by Ryeng et al. is available on open-access here: www.doi.org/10.1007/s00300-021-02970-w