Endobiont infestation, shell strength and condition index in wild populations of New Zealand abalone, Haliotis iris

Abstract

Anecdotal suggestions that abalone in northern New Zealand are more heavily infested with endobiont sponges and polychaetes than those in the south led to a comparison of populations in the two regions. Shells from wild populations of Haliotis iris were examined by X-ray analysis to evaluate the degree of infestation and penetration. The mechanical strength of shells and condition index of the abalone were measured and compared with the degree of endobiont infestation. There were no significant differences in measured characteristics in abalone from the northeastern region of New Zealand (36°16′–36°22′S) compared with those from the South Island (40°44′–41°11′S) nor among populations within these regions. Shell strength, previously unknown for abalone, was considerably weakened by bifacial porosis and was correlated with condition index.