▁brown - green ▁to ▁black ▁or ▁blue . ▁For ▁und et erm ined ▁reasons , ▁populations ▁in ▁the ▁Frank land ▁River ▁system ▁on ▁the ▁West ▁Coast ▁are ▁pre domin antly ▁found ▁to ▁be ▁blue - white ▁in ▁colour . ▁ ▁M ales ▁can ▁be ▁identified ▁by ▁their ▁larger ▁p inc ers ▁compared ▁to ▁females . ▁Young ▁ju ven iles ▁mou lt ▁several ▁times ▁a ▁year , ▁becoming ▁less ▁frequent ▁as ▁they ▁m ature . ▁The ▁species ▁is ▁long ▁lived ▁and ▁known ▁to ▁live ▁up ▁to ▁ 6 0 ▁years ▁of ▁age ▁and ▁att ain ▁weights ▁of ▁up ▁to ▁, ▁however ▁in ▁recent ▁years ▁spec im ens ▁of ▁ ▁are ▁considered ▁large . ▁ ▁Results ▁from ▁a ▁gen etic ▁study ▁indicated ▁that ▁spec im ens ▁of ▁A . ▁g ould i ▁from ▁a ▁site ▁in ▁the ▁P ip ers ▁River ▁catch ment ▁( n orth ▁of ▁La unc eston ) ▁were ▁significantly ▁gen et ically ▁distinct ▁from ▁the ▁rest ▁of ▁the ▁species . ▁ ▁Be hav iour ▁The ▁dispers al ▁and ▁mig rat ory ▁patterns ▁of ▁A . ▁g ould i ▁are ▁largely ▁unknown , ▁but ▁they ▁are ▁recorded ▁to ▁be ▁most ▁active ▁during ▁summer ▁and ▁aut umn ▁when ▁water ▁temper atures ▁are ▁higher , ▁they ▁are ▁also ▁known ▁to ▁walk ▁over ▁land . ▁A ▁ 2 0 0 4 ▁study ▁found ▁the ▁species ▁appears ▁to ▁have ▁periods ▁of ▁relative ▁in activity ▁restricted ▁to ▁a ▁" home - pool " ▁for ▁ 1 – 1 0 ▁days ▁inter sp ers ed ▁with ▁movements ▁involving