DAILY MOVEMENT PATTERNS OF THE SPINY LOBSTER JASUS-EDWARDSII (HUTTON) ON A SHALLOW REEF IN NORTHERN NEW-ZEALAND

Daily movement patterns of spiny lobster Jasus edwardsii were investigated in north-eastern New Zealand during 1984 and 1985. The position of tagged lobsters was recorded by searching a mapped area of shallow (< 10 m deep) rocky reef at intervals during day and night. Handling during capture for tagging had short-term effects on behaviour. Spiny lobsters were crepuscular and nocturnal although daytime movements were also common during the mating period. No significant relationship was detected between activity of J. edwardsii and any environmental factor, including sea temperature, hours of darkness or moonlight or population density. Individual spiny lobsters moved in relation to local topography. The median total distance moved at night was 41 m while the median foraging range was only 24 m. The frequency distribution of distance moved was dispersed and near-exponential in distribution, a reflection of the wide range in lobster size and moult state. Activity of spiny lobsters during April-July appeared related to mating. Most premoult females were active at night and moved shelters between consecutive days enabling choice of shelters or mates. Mature males either stayed within their shelter and mated with cohabiting females or moved among shelters by day and night in search of receptive females. During the mating period the total distance moved at night by males greater-than-or-equal-to 140 mm CL was inversely related to size. Any impact J. edwardsii have on prey populations will be restricted to near-daytime shelter.