Diversity At A Glance

This is a new column, geared towards people working in specific areas of biodiversity, who may be ‘neophytes’ to other fields. It aims to introduce interesting species of Hong Kong flora and fauna that might be encountered during fieldwork. Distinctive physical characteristics and some interesting ecological facts are included for each example. If you wish to contribute to this column, or have any comments or suggestions, please contact either
Jacqui Weir (jesweir@hkusua.hku.hk) or Sukh Mantel (skmantel@hkusua.hku.hk).

	'The last remaining abundant grouper in Hong Kong'
	'Spilt-gill fungus Schizophyllum commune Fr.'
	'Rousettus leschenaulti (Rousettus Fruit Bat / Leschenault's Rousette Bat)'

'The last remaining abundant grouper in Hong Kong waters'

by Liu Min

The Chocolate hind, Cephalopholis boenak (Bloch, 1790) is the smallest and last remaining abundant grouper in Hong Kong waters (Fig. 1). Its commercial value in Hong Kong live fish markets has increased in recent years, since the larger groupers have been over-fished. C. boenak is a diandric protogynous hermaphrodite i.e., it has two pathways of male development. Primary males develop from juveniles directly through sexual differentiation and secondary males from females through sex change. It is strongly associated with corals and prefers hard corals, such as Pavona decussata and Platygyra acute, that provide plentiful crevices and holes for settlement and refuge. The fish live in small social groups consisting of a single large dominant male, two to five smaller females and several juveniles. Spawning season in Hong Kong waters is from April to October. Social control of sexual differentiation in juveniles and sex change in adults has been demonstrated in the laboratory. Juveniles develop into males when kept singly, while the largest fish developed into males when in pairs, triplets or quartets. Removal of the dominant male from a social group induced the largest remaining female to change sex to male. The Chocolate hind can also change sex from male to female in all-male groups. After understanding the habitat association and coral preferences of C. boenak, we realize that the traditional fishing management, such as limited landing size/quota, is not applicable to this species. Protecting the corals they live in by setting up marine reserve areas could be effective.