THE USE OF BEAKS AS TOOLS FOR BIOMASS ESTIMATION IN THE DEEP-WATER SQUID MOROTEUTHIS-INGENS (CEPHALOPODA, ONYCHOTEUTHIDAE) IN NEW-ZEALAND WATERS

Beak lengths (lower rostral length and upper rostral length) were take n for a sample of Moroteuthis ingens which were captured on the Chatha m Rise, New Zealand. Beak lengths were plotted against both mantle len gth and wet weight to determine the relationship between these paramet ers for future use in biomass estimates in predator analysis. Although M. ingens is markedly sexually dimorphic, with females reaching 5 tim es the weight of males, there was no obvious sexual dimorphism in eith er lower or upper rostral length. This resulted in sex-specific relati onships between both LRL and mantle length, LRL and weight; and URL an d mantle length, and URL and weight. Males appeared to have a curvilin ear relationship between beak length and mantle length and beak length and weight (even for log-transformed data). There was also considerab le spread in the data in the plot between beak length and weight for f emales of similar weight. These characteristics of the data makes biom ass estimates based on rostral length measurements for this species di fficult. Other beak parameters may prove more useful for estimating bi omass of M. ingens.