Rate and extent of decline in Corallium (pink and red coral) populations: existing data meet the requirements for a CITES Appendix II listing

摘要

ABSTRACT: In June 2007, the US government proposed Corallium (pink and red corals) for listing on Appendix II of the Convention on International Trade in Endangered Species (CITES). The proposal was adopted and later overturned due to perceived difficulties in implementing and enforcing a CITES listing and uncertainties on population status. An expert review (Food and Agriculture Organization) questioned whether populations had declined to 20–30% of the historic baseline, the level required for a CITES Appendix II listing. This review used colony abundance and density as surrogates of decline, which may be high (200 to 1300 colonies m–2) in the Mediterranean. Yet assessments of decline for colonial organisms should also consider changes in size, since reproductive output and survival increase exponentially with size. Colonies of C. rubrum historically achieved heights of 50 cm with complex first, second and third order branching patterns. Today, 90% of colonies in fished areas are 3 to 5 cm tall, 50% are sexually mature and most have only rudimentary branches. Few population data are available for Pacific Corallium spp.; however, landings over the last 15 yr have declined from 100–400 to 5 t yr–1. Recovery of populations to their natural state may require decades, as colonies in protected areas are less than half their historic size after 20 to 30 yr of protection. Minimum allowable size for harvest should be increased because traditionally determined growth rates appear to underestimate colony age, and corals are being removed long before achieving maximum sustainable yield. ‘Boom and bust' cycles of Corallium fisheries and dramatic, long-lasting shifts in population demography highlight the need for improved management and trade regulations.