Skin Deep: An Assessment of New Zealand Blue Whale Skin Condition

• Main Authors: Barlow, Dawn R., Pepper, Acacia L., Torres, Leigh G.
• Other Authors: Fisheries and Wildlife, Oregon State University. Undergraduate Research, Scholarship, and the Arts (URSA), Hatfield Marine Science Center, Oregon State University. Marine Mammal Institute
• Format: Article in Journal/Newspaper
• Language: English
• Published: Front. Mar. Sci.
• Subjects: Dalatiidae > New Zealand; Blue whale > New Zealand; Skin > Abnormalities; New Zealand; Blue whale
• Online Access: https://ir.library.oregonstate.edu/concern/defaults/xk81js512

Skin condition assessment of wildlife can provide insight into individual and population health. Yet, logistics can limit skin condition assessment of large whales. We developed a standardized, quantitative protocol using photographs to assess skin condition of blue whales in New Zealand, and demonstrate the value gained by testing hypotheses, documenting new morphologies, and establishing baselines that can be monitored for change. We reviewed a photo-identification catalog to compile common markings, categorized markings according to existing definitions, and described markings not previously documented. Photographs of blue whale skin (n = 1,466) were assessed to quantify marking prevalence, severity, and co-occurrence patterns. Of the whales assessed (n = 148), 96.6% had cookie cutter shark bites, 80.4% had blister lesions, 56.0% had pigmentation blazes on the dorsal fin, and 33.7% had holes in the dorsal fin. Additionally, 35.8% had “starburst” lesions, a previously undocumented marking. Blister and cookie cutter shark bite severity did not accumulate linearly, indicating that the two marking types are unrelated. There was a positive relationship between blister severity and number of starbursts, indicating that the two could be related; based on morphological similarities, starburst lesions may derive from ruptured blisters. Whales with holes in their dorsal fin had significantly higher blister severity than those without, indicating that these markings could be related; this is supported by observed blisters on dorsal fins of blue whales. There was a significantly higher probability of fresher cookie cutter shark bites on whales observed at more northerly latitudes, but no relationship between blister severity or number of starbursts and latitude. These latitudinal patterns indicate that blue whales in New Zealand accumulate cookie cutter shark bites at more northerly latitudes; this finding is supported by the known range of cookie cutter sharks in New Zealand waters. Of the eight individual whales ...