The scribbled angelfish Chaetodontoplus duboulayi

Anecdotal information has suggested that some populations of the scribbled angelfish (Chaetodontoplus duboulayi, pictured) may be depleted. Although this information has not as yet been validated by scientific surveys, local fishers in Queensland, Australia, have observed significant fluctuations in population densities over the years and thus have raised concerns. Population estimates between the Keppel Island group and the southern extent of the species in Hervey Bay, Australia, show lower population numbers than in the past. Scribbled angelfish are an important species in the aquarium trade because they are 'endemic' to Australia and Papua New Guinea, hence rare and therefore in high demand. According to GMAD data 3,544 (total) of this species were exported from Australia1™1" between 1988 and 2001.

Individuals of this species tend to be found relatively close to shore, in soft reef and sponge reef habitats, in the turbid waters that stretch from Hervey Bay north to Papua New Guinea. In the Cairns region, anthropogenic influences have severely impacted this habitat and may have indirectly led to declines in scribbled angelfish populations. Although fishing pressure is thought to be one of a number of impacts to have affected numbers, biological and other fema le41,132. The effects of fishing are significantly different for species that are hermaphroditic compared with species that do not change sex. A fishery selectively removing larger animals first will mean that animals will have to start changing sex at smaller sizes, possibly reducing the fitness of individuals, and thus making hermaphroditic stocks more vulnerable to overfishing. Greater fishing pressure, together with the biological and ecological characteristics of some of these species, may make them more vulnerable to exploitation than other fish species41. Life history traits of fish are associated with

1/A 1/7 1 / ft their vulnerability to exploitation , , their rarity and their risk of extinction149-151.

Trade in ornamental marine fishes tends to be characterized by extreme selective harvesting. For all species, with the possible exception of smaller species such as gobies, blennies and dottybacks, juveniles are preferentially targeted by aquarium fish collectors due to their distinctive coloration, ease of maintenance and size-ratio with respect to tank size37. A study carried out in Hong Kong showed that 56 per cent of 12,652 fishes ready for retail sale were juveniles24. Such preferences may potentially reduce the risk of over-harvesting by leaving

Scribbled angelfish, Chaetodontoplus duboulayi: female (left) and male (right).

characteristics, such as annual recruitment patterns dependent on seasonal temperature or rainfall, habitat alteration due to trawling, and sedimentation and pollution may have contributed to their decline.

Baseline information and general life history data are needed on this species to help make more informed decisions regarding its collection for the aquarium trade. Establishing areas closed to the fishery of this species, as well as limiting commercial effort in the fishery, have been suggested as recommendations to prevent further depletion of these fish stocks.

Source: QFMA41

breeding adults on the reefs. However, should juveniles consistently be heavily harvested, adult populations will suffer as only a limited number of young will grow to reach adult size and replenish the adult stock.

Most coral reef fishes have broad distributions152. Some species such as the Moorish idol, Zanclus cornutus, are distributed throughout most of the Pacific and Indian Oceans. A small number of species, on the other hand, are known only from restricted waters and/or are known as endemics. In assessing the conservation value of these endemic species, distribution and abundance must be distinguished. Some species are naturally rare, occurring only in very restricted locations, or naturally occur in lower numbers, even though they may be widely distributed6. Other species may be abundant at different sites, but their distribution is limited to specific habitats41. The more widespread and/or abundant a species is, the less vulnerable it is to exploitation.

Increased rarity often implies higher prices6. Individuals of two rare species, the yellow-faced angelfish, Pomacanthus xanthometapon, and the blue-girdled angelfish, Pomacanthus navarchus, fetch prices in the range of hundreds of dollars in the United States37. The peppermint angelfish Centropyge boylei may command a price as high as US$10,0 0 037. Officially protected species may artificially drive prices up for the few licensed to trade in them (e.g. seadragons, Phycodurus eques and Phyllopteryx taeniolatus)37. However, high prices are not necessarily an indication that a species is rare and therefore vulnerable to overcollection6. The deep reef species, Tinker's butterflyfish, Chaetodon tinkeri, can sell for up to US$1,000 per pair and has a restricted range, occurring only in the Marshall, Johnston and Hawaiian Islands. However, the high price is probably driven by the difficulty in collecting the fish as it lives at depths of 27 to 135 m153. Furthermore, due to the depth at which this species occurs it is possible that it is more abundantly distributed than at first appears.

Caution should be exercised when examining the rarity of individual species. For example the raccoon butterflyfish, Chaetodon lunula, the blackwedged butterflyfish, Chaetodon falcula, the dwarf angelfish, Centropyge multispinis, and the regal angelfish, Pygoplites diacanthus, are rare off Sri Lanka, making collection inadvisable, but abundant in the Maldives where populations could maintain sustainable collection6. Hence, in order to encourage protection and conservation of these species in Sri Lanka's waters, hobbyists should try to purchase specimens originating from the Maldives (and/or Mozambique in the case of the dwarf angelfish)6.

Information relating to Pterapogon kauderni and

Hippocampus spp. will be presented and used as examples to demonstrate species vulnerability to collection for the marine ornamental trade.

Pterapogon kauderni

The Banggai cardinalfish, originally described by Koumans in 1933 and 'rediscovered' in 1991121, is a popular fish amongst hobbyists and public aquarists due to its attractive appearance and the ease with which most individuals readily acclimatize to aquarium confines131. A paternal mouth brooder (males incubate the female's eggs in their mouths until after hatching of the young), the Banggai cardinalfish is a small (maximum 55 mm58) species of fish that is relatively common, but whose distribution is restricted to the shallow waters (reef and seagrass habitat) of the Banggai Islands, an area of approximately 10,000 km2 off the east coast of central Sulawesi, Indonesia. It usually lives in groups of 20 to 200 individuals that hover above long-spined sea urchins, Diadema setosum, or branched corals that the species uses as a refuge if threatened154, 155. Juveniles are also known to associate and take shelter in the fungiid coral Heliofungia actiniformis and anemones156, 157.

Biologists and conservationists have expressed concern about the potential impact of collecting this species for the aquarium trade155 due to:

□ the high and increasing fishing levels recorded over the species' entire distributional range156, e.g. 180,000 fish per month being sold in the Banggai region75

□ its restricted habitat158

□ its low fecundity (lowest recorded fecundity rate of all apogonids) and increased energy invested in parental care

□ its low dispersal rate due to the lack of planktonic dispersal of its eggs121

Banggai cardinalfish, Pterapogon kauderni.
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