New Zealand Journal of Marine and Freshwater Research abstracts

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Growth and morphometrics in the New Zealand sea urchin Pseudechinus huttoni (Echinoidea: Temnopleuridae)

Selena Kirby*
Miles D. Lamare
Mike. F. Barker

Department of Marine Science
University of Otago
P.O. Box 56
Dunedin, New Zealand
email: miles.lamare@stonebow.otago.ac.nz
*Present address: SCDNR Marine Resources Division, Hollings Marine Laboratory, 331 Fort Johnson Rd, Charleston, SC 29412, United States.

Abstract We examined somatic growth in the New Zealand sea urchin, Pseudechinus huttoni. This species normally inhabits the continental shelf, but in the New Zealand fiords can be found at shallower depths. These shallower populations provided an opportunity to quantify growth of these deep water sea urchins using chemical tag recapture techniques. Growth was modelled in three Doubtful Sound populations and varied spatially, with maximum test diameter (TD) and maximum growth rates ranging from 33.8 to 42.7 mm TD and 2.9 mm yr–1 to 23.9 mm yr–1, respectively. Size-at-age modelling suggests that P. huttoni is c. 5–15 mm TD at 1 year, 20–30 mm TD at 4 years, and adults approach a maximum size of 30–40 mm TD after 6 to 11 years. Growth in continental shelf populations was inferred from measured growth in the fiord population by comparing population statistics (size structures, mean size), morphometrics, and nutritional status among both habitats. Our results indicate that growth of P. huttoni populations on continental shelves varies spatially (with depth), but is within the range of growth measured in the Doubtful Sound populations. A generalised growth model for P. huttoni based on the three Doubtful Sound populations is described by the Brody-Bertalanffy equation St = 42.17(1–0.99e (–0.229t)).

Keywords sea urchin; echinoid; growth; Pseudechinus huttoni;Brody-Bertalanffy equation; Doubtful Sound; Otago Shelf

New Zealand Journal of Marine and Freshwater Research, 2006, Vol. 40: 413–428
0028–8330/06/4003–0413     © The Royal Society of New Zealand 2006
M05076; Online publication date 7 July 2006. Received 22 December 2005; accepted 31 March 2006

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