Wrassling With A Tasty Threat

November 11th, 2013 BY Hilary Feldman | No Comments

It doesn’t have the most appetizing name, but the humphead wrasse suffers from being too tasty. In the past, it was a sought-after food fish earmarked for the top levels of society only. Now the demand is from the live reef food fish trade. The pressure has put this species in the endangered category on the IUCN’s Red List.

Humphead wrasses, Cheilinus undulatus, live across the Indo-Pacific, where they are one of the largest coral reef fishes. The live reef food fish trade relies on the successful capture and storage of live fish. These animals are then transported to markets such as Hong Kong, Taiwan, and Singapore. The trade exists despite being listed on the CITES Appendix, banning trade in certain countries.

Typical reef fishing techniques can be devastating. While some wrasses are caught with traps, spearguns, and by hook and line, often cyanide is used. Rather than targeting the specific fish desired, cyanide fishing kills many reef inhabitants, including corals. Often smaller immature wrasses are caught this way. Some then go on to be sold for saltwater aquaria, while the majority are destined for high-end restaurants.

Humphead wrasses are particularly sensitive to even the mildest level of fishing pressure. They have predictable reproductive patterns – both in space and time – and cluster to breed, inadvertently enabling large groups to be targeted for capture. In contrast, normal population densities are quite low for this species, making them a fishing challenge outside of the breeding season. It may take up to five years for individuals to reach reproductive maturity, with life spans of 30 years or more. In addition, these fish undergo sex reversal as part of their life history, with smaller fish usually being female while older larger fish may become male. By frequently removing juveniles, populations subject to fishing never have the chance to recover and renew themselves. Without younger fish, the sex ratio becomes skewed and aging adults cannot support sufficient numbers.

Despite international agreements and conservation efforts, many countries still lack clearcut management plans or enforcement practices. So illegal fisheries face little challenge. Add in the financial incentive, which is substantial when prices can reach $100 per kilogram of wrasse.

Large predators on reefs, these wrasses eat molluscs, echinoderms, and crustaceans. They even consume crown-of-thorn sea stars, which are known for their dire impact on coral reefs. As with any ecosystem, the removal of larger predators can often have serious knock-on effects. Obviously, depleting the population to satisfy short-term gustatory goals could have ramifying effects for reef diversity in the Indo-Pacific region.

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