Mesophotic Coral Ecosystems

6.5. Marine aquarium trade

The international marine aquarium trade involves the collection, breeding and supply of many shallow and mesophotic reef fish, corals and other invertebrates for home and public aquaria. Marine life in the trade is supplied from 40–45 countries (Rhyne et al. 2012). Estimates suggest that approximately 150 hard coral species and 1,500 fish species (across 50 families) are actively targeted by the marine aquarium trade (Wabnitz et al. 2003). Recent research has highlighted the role of the Philippines and Indonesia as the dominant global exporters, responsible for 55 per cent and 31 per cent, respectively, of all live fish imports into the United States for 2005 (Rhyne et al. 2012). The United States imported approximately 11million fish during the year 2004–2005 (Rhyne et al. 2012), and the Europeanmarket is of a similar size (Wood 2001). This suggests a global trade of over 22 million fish annually. Currently, most monitoring of the marine aquarium trade is based on the Convention on International Trade in Endangered Species (CITES) permits or packing lists for international shipping of live fish. It is unclear what proportion of the traded marine life is collected from MCEs. However, there is trade in mesophotic reef fish species with countries such as Japan, where there is an enthusiastic market for ‘rare’ mesophotic fish species. Traded mesophotic species include anthias (Subfamily: Anthiinae; Figure 6.10), dottybacks (Family: Pseudochromidae), butterflyfish (Family: Chaetodontidae), wrasse (Family: Labridae) and pygmy angelfish (Genus: Centropyge). In particular, within the pygmy angelfish, the Peppermint angelfish ( Centropyge boylei ) and the Narcosis angelfish ( Centropyge narcosis ) are highly prized (see case study). Mesophotic fish are commonly labelled as ‘rare’ by

the marine aquarium trade, but this is likely to reflect their limited supply due to the difficulties of collection rather than true ecological rarity. With current collection pressure quite dispersed over large reef areas, it is unlikely that the marine aquarium trade is having a large impact at mesophotic depths. However, populations of many mesophotic reef fish species lack quantitative assessments, making sustainable collection quotas hard to set. As many mesophotic fish species in the aquarium trade have gas-filled swim bladders which expand and burst if fish are brought too rapidly to the surface (Munday et al. 2015), careful planning is required to bring them to the surface without injury. Traditionally, collectors have carefully punctured the swim bladder of the fish using a needle on ascent, though this may result in increased infection risk later. Many collectors still use ‘needling’ to bring collected fish to the surface (Figure 6.11), although, increasingly collectors are using decompression stops to allow fish time for gas to move out of the swim bladder during ascent. Work on Yellow Tang ( Zebrasoma flavescens ) on Hawaiian shallow reefs found that ‘needling’ to vent excess gas from the swim bladder reduced immediate mortality post- dive, but led to elevated serum cortisol (a proxy for fish stress), whereas the addition of decompression stops led to lower increases in serum cortisol (Munday et al. 2015). In terms of scleractinian corals, it is unlikely that many are being collected from mesophotic depths, as most coral species in high commercial demand are found in greatest abundance on shallow reefs or reef slope environments less than 30 m in depth. With increased availability of advanced diving technologies, which allow access to greater depths, there could be an increase in demand for mesophotic species in the future.

Figure 6.10. Anthias, Pseudanthias bimaculatus , collected at 50 m in the Maldives for the marine aquarium trade (photo ElizabethWood).

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