The sole assessment enigma

Up to the turn of the Century, the sole resource had “behaved by the book”: A steady annual catch of about 700 mt with a similarly steady CPUE over the last two decades (at least).

Then, without any change in the TAC, the catches started to drop. Initially this was driven mainly by a decrease in effort as old vessels were retired from the fishery. But then a decade into the new Century, the CPUE dropped markedly too, by some 50%.

Thus the key question for the IWS Panel is: What parsimonious revisions to the assumptions underlying the current sole model do you suggest for further investigation?