The estimation of live fish size from archaeological cranial bones of New Zealand Red Cod Pseydophycis bachus: Tuhinga 12

Tuhinga 12: 17 - 38

ABSTRACT: The New Zealand Red Cod (Pseudophycis bachus) is a common fish in archaeological bone collections from New Zealand. It is not a true cod (family Gadidae) but a member of the family Moridae. The Maori name is hoka. The species is present in 77 of 126 archaeological sites in which fish remains have been studied, with a strong southern bias in abundance. This paper establishes a method for reconstructing fish size and weight from archaeological bones. Twenty measurements were taken on five of the paired cranial bones of a modern sample of the New Zealand Red Cod (Pseudophycis bachus). Regression analysis was performed on these measurements to estimate total fish length and fish weight. A number of regression models were examined (linear, logarithmic, exponential, and power curve) to work out the optimal estimator for each bone measurement. It was found that total length of this species can be estimated with a standard error of less than 23 mm, and weight to less than ± 194 g. Coefficients are provided for 40 equations linking bone size to fish length and weight, This is followed by an example of how to apply the equations to a small bone collection of red cod from an archaeological site at Raumati Beach near Wellington in order to reconstruct the size frequency of the original fish catch.

KEYWORDS: New Zealand, archaeozoology, Moridae, Pseudophycis bachus, regression analysis, length and weight estimation.