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Studies on the Paua, Haliotis iris Martyn in the Wellington district, 1945-46

Growth Relation

Growth Relation

Sasaki (1926) recorded the growth relation between the shorter and longer diameter in H. gigantea and in two varieties of H. gigantea from places varying in temperature in Japan. He took the ratio at Omoi as the mean (71.29) and he read his results to show that high temperature probably produced narrower shells. Crofts (1929) found the ratio for H. tuberculata was 68.7 in the Channel Islands.

In H. iris from the Runaround and Chaffer's Passage, Wellington, the ratio is 75.7 for 120 specimens varying from 9 to 17cm in longest diameter. They, therefore, are wider than H. tuberculata at Brecqhoua (Channel Islands) or any H. gigantea specimens mentioned by Sasaki. Ten specimens from Kaikoura gave a ratio of 78.1 which is wider again than any of the specimens mentioned above. In small H. iris varying from 5 to 50mm the shells are narrower not wider as Crofts (1929) found in H. tuberculata but the ratio is not constant. H. australis specimens give a ratio very close to that of H. iris, namely 70.0.

Sasaki found that the growth relation between shorter and longer diameters in H. gigantea could be expressed by the equation S = kLx where S is the shorter diameter; L the longer diameter; k the local constant and x the specific exponent. The probable specific exponent for H. gigantea is 0.85 for mature specimens and for immature specimens 0.97 showing that the larger shell is the narrower. In H. iris the following values for the specific exponent were obtained; 0.98 for mature specimens and 0.96 for immature specimens. These values for the specific exponent indicate that in H. iris the larger shells are wider. No record of temperature range for the places in New Zealand from which the calculations on H. iris and H. australis were made were available to the writer. Consequently no correlation between the growth relation figures and temperature could be made as in the paper by Sasaki (1926).