EFFECTS OF CLIMATE CHANGE AND FISHING PRESSURE ON CIGUATERA PREVALENCE IN HAWAIIAN REEF FISHES: IMPLICATIONS TO PUBLIC HEALTH IN A CHANGING CLIMATE

Ciguatera fish poisoning (CFP) is caused by consuming reef fishes containing toxins produced by epiphytic dinoflagellates in the genus Gambierdiscus. Changing reefscapes due to climate change and altered reef fish assemblages from overfishing may increase the range of and habitat available to Gambierdiscus spp. while altering how ciguatoxins (CTX) move through coral reef food webs. However, it is not clear how these factors may interact to influence the probability of ciguatoxic fishes and thus the risk of CFP to local communities dependent upon these fisheries. Therefore, the objectives of this study are to 1) evaluate the relationship between a suite of habitat characteristics at multiple spatial scales, including those related to changing temperature regimes and fishing pressure on the probability of fish testing positive for CTX; 2) evaluate the relationship of the same habitat characteristics on the concentration of CTX; and 3) assess the degree to which local fishing communities practices and beliefs that are used to limit risk of CFP agree with the findings of the first two objectives. I evaluated the presence and concentration of ciguatoxins in two common reef fish species: the high-level predator, Peacock Grouper (Cephalopholis argus), hereafter referred to by its Tahitian name – Roi, and a frequently sought-after herbivore, Goldring Bristletooth (Ctenochaetus strigosus), known as Kole in Hawaiian, sampled bi-annually across four sites along west Hawaiʻi Island. For Roi, both the probability of testing positive for CTX and CTX concentration exhibited a positive relationship to length and negative relationship to the number of days under a coral bleaching alert and fishing pressure. For Kole, the probability of testing positive for CTX was negatively related to length, the number of coral bleaching alert days, effluent, fishing pressure. The concentration of CTX in Kole was also negatively related to length, effluent, fishing pressure, and mean percent live coral cover. Most anglers and spearfishers are unlikely to restrict their fishing activity in response to CFP risk, instead tending to avoid species, size classes, or fishing areas perceived as high risk. However, my results suggest that fish behaviors are likely to become less effective as changing temperature regimes, loss of live coral cover, and human fishing pressure may be altering the prevalence and distribution of ciguatoxic fishes. The results of the study will allow resource managers to better communicate the risk of CFP to anglers and spearfishers so they can mitigate the dangers of ciguatera fish poisoning in a fast-changing climate.

Keywords

Aquatic sciences, Cephalopholis argus, Ciguatera fish poisoning, Climate change, Ctenochaetus strigosus, Perceived risk, Public health risk

URI

https://hdl.handle.net/10790/42737

Extent

60 pages

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Tropical Conservation Biology and Environmental Science

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