Carpenter’s Cannibal Salmon

 

 

Atlantic Salmon (public domain image)

 

War loomed large on the front page of the Northern Daily Mail on 1 Sept. 1939. Poland is complaining about being a victim of German aggression and Hitler is making provocative speeches.

The British Association for the Advancement of Science was meeting in Dundee and the anxious committee decided to cancel the remainder of the meeting.   The night trains to London and other parts of the country were simultaneous booked up with all available sleeping accommodation reserved.

Kathleen Carpenter (from Liverpool University) was lucky, because earlier in the day she got to report on one of the first detailed studies of the diet of young salmon (Vol. 110: 81-96, 1940: Proceedings of the Zoological Society of London).  She had examined hundreds of young salmon from the Welsh Dee over a two year period.

Several newspapers ran headlines on the theme of “cannibal salmon” and contained almost identical quotes from Dr. Carpenter:
“The result is to show that the young salmon are wholly opportunists in their feeding, taking greedily any sort of animal food which is available, no matter what its nature and origin.”

“The stomach contents include examples of almost all the invertebrate animals found in the streams, and also such miscellaneous items as a bird’s feather, a mole-flea, ants, spiders and millipedes, many winged insects, portions of the skeletons of fishes, and some unmistakable salmon eggs.”

“The interest of this new record of cannibalism is enhanced by the fact that one parr, which had swallowed five of these eggs, was a prematurely ripe and already spent male, and so may quite possibly have eaten his own offspring.”

The abstract of her scientific paper described the salmon as “indiscriminately carnivorous”- they ate whatever was available at the time.   She considered material from outside the river ecosystem important, especially leaf-eating tree-parasites which fall into the river in the autumn.  For this reason she thought the growth of riparian trees and vegetation desirable. Fish scale readings seemed to correspond to the seasonal cycle in feeding.  In her opinion there is no evidence of loss of appetite at any season but merely variations in opportunity.

This paper was Kathleen Carpenter’s last contribution to the scientific literature.

Three days after the aborted Dundee meeting on the 3rd Sept., Britain declared war of Germany. Presumably Kathleen Carpenter returned safely to Liverpool.  In a review of the pollution of rivers of West Wales in 1944 (which was first documented by Carpenter), Lily Newton remarks in a footnote that a complete set of scientific records were destroyed in enemy action.  There is no acknowledgement of any assistance from Kathleen Carpenter. To add to the mystery Liverpool University archives have no record of Kathleen Carpenter.

You can find out more about Kathleen Carpenter at my International Women’s Day lecture at Aberystwyth University on the evening of 7th March 2016 – details here. If you have any records for her in Liverpool during or after the Second World War please get in touch.