Holkham, 21 oktober 2016 – A CSIP team from ZSL carried out a field necropsy over Friday afternoon on the juvenile female fin whale (national reference SW2016/584), which was found dead stranded at Holkham in Norfolk on 20th October.
We found that the 13m whale was in very poor nutritional condition, with the transverse processes of the spine visibly protruding along the rear part of the body and notable hollowing of the dorsal flanks. No evidence of previous entanglements or of fresh injuries consistent with recent ship strike was found, although we couldn’t examine the left side of the body due to the stranding position. Abrasions on the underside of the keel and on the leading edge of the right tail fluke, together with the fresh nature of the carcass on initial discovery, were all considered to be consistent with recent live stranding. There was no evidence of recent feeding and minor parasite burdens were present at various sites in the body. The organs were all moderately decomposed, despite the animal probably having died within the last few days.
There was a distinct kink or curvature in the body shape, with an approximate 30-40 degree bend in the tailstock, with an associated dorsal ‘hump’. The curvature was largely in a vertical direction, but there was also some lateral distortion from the midline, with displacement somewhat to the left. The location of the ‘hump’ approximately corresponded with some scarring noted on the ventral abdominal region (just caudal to the termination of the throat pleats). When we dissected the ‘humped’ region, we found that the spinous processes of the vertebra were misaligned, illustrating the general misalignment of the spine. The surrounding musculature on the right side of the body also appeared to be much more oedematous and reddened compared to that on the left, although this may be partly associated with live stranding.
So to summarise, the evidence from the post mortem indicates that the fin whale had developed a spinal abnormality (possibly a kyphosis or kyphoscoliosis), which had potentially limited the degree of movement and lead to the progressive wasting of the musculature and eventual live stranding and death. The degree of muscle wasting appeared much more profound along the tail-stock, behind the ‘hump’, so we speculate that the spinal abnormality had limited the degree of movement in that region in particular, which would have impacted on the animals ability to dive and feed. The spinal abnormality may have been congenital, but it is certainly possible that the whale may have survived an historical traumatic event. However, we cannot confirm or rule this out this without having examined the other side of the whale to look for other evidence of scarring or traumatic injuries. We’d very much appreciate any images or footage taken of the left side of the whale, as this may help us learn more about the possible reasons for its death and stranding.
The results of other analyses are pending completion and may alter the final cause of death, but it has provisionally been given as ‘starvation, consequential to spinal abnormality (kyphosis or kyphoscoliosis)’.
We owe a huge debt of thanks to the Holkham Estate and to Natural England for helping to facilitate our examination of the whale, in particular to Sarah Henderson and her team and to all our colleagues at Natural England who helped out on the day.
Images credit CSIP-ZSL.
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