New Zealand Journal of Marine and Freshwater Research abstracts

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BIOLOGY OF EVECHINUS CHLOROTICUS (ECHINOIDEA: ECHINOMETRIDAE) FROM DIFFERENT LOCALITIES 2. MOVEMENT

Trevor G. Dix*

Zoology Department, University of Canterbury, Christchurch, New Zealand

Abstract During late December 1967 and January 1968, 310 Evechinus chloroticus (Val.) were tagged with anchor tags at four marked subtidal sites in Third Bay, Kaikoura. Tag recoveries after 3, 6 and 9 months were approximately 57%, 26% and 17%. Tagged urchins were recovered only at the marked sites and only small numbers (6% at 3 months and 10% at 6 months) had moved between sites; these urchins had moved 'from the nearest neighbouring sites, the maximum distance between these being 4.8 m. Gonad condition and amount of food in the gut were compared for 50 tagged and 30 untagged urchins 9 months after tagging. Of tagged urchins, only five had gonads of normal size and appearance and only 18 could be sexed. Mean gonad indices of tagged and untagged urchins were 0.43 and 1.12. The amount of food in the gut of tagged specimens was generally less than that of untagged specimens. Tag insertion holes were not sealed by regenerated test and no significant changes in test diameter had occurred in tagged specimens after 9 months. In October 1968, 27 Evechinus were tagged in situ underwater at Kaiteriteri and four of these were recovered alive after a month, one at the tagging site and one at each of three positions 3 m, 4 m, and 5 m from the tagging site. Although mortality probably accounts for most Of the fall in tagged recoveries, other evidence suggests that the pattern indicated by tagging, of very little movement of subtidal Evechinus at Kaikoura with more at Kaiteriteri, reflects the natural situation. The amount of movement may be related to the availability of food. Evechinus moved more at night than during the day in running sea-water tanks.

N.Z. 31 mar. Freshwat. Res. 4 (3): 267-77.
(Received for publication 26 September 1969)

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