Wahoo and Mercury

The full text of FMRI* Technical Report TR-9 is available for download on the Technical Reports page of the Web site.

The wahoo, Acanthocybium solandri, is an offshore pelagic species with a global distribution in tropical and subtropical waters. The biology of wahoo is not well understood, but FWC-FWRI is currently examining the life history characteristics of this species in Florida waters. Wahoo in the subtropical Atlantic and Gulf of Mexico are thought to spawn during summer months (Wollam, 1969; Hogarth, 1976), but preliminary data from the northern Gulf of Mexico and Bahamas suggests the possibility that limited spawning occurs in the early spring (Brown-Peterson et al., 2000). Very little is known regarding the abundance and distribution of wahoo, but they are caught year round in Florida waters (SAFMC, 1998), with peak catches occurring during summer months (FWC-FMRI, 2001). Wahoo can attain a length of approximately 2,100 mm and a total weight of 83 kg (FWC-FMRI, unpublished data).

Preliminary results from a recent genetics study strongly suggest that wahoo in the Gulf of Mexico and off the U.S. Atlantic coast comprise one population (J. Franks, personal communication, Gulf Coast Research Laboratory, Ocean Springs, MS). Wahoo feed principally on pelagic fishes (e.g., flying fish, Cypselurus spp.; ballyhoo, Hemiramphus brasiliensis; porcupinefish, Diodon hystrix) and, to a lesser extent, invertebrates (e.g., squids) (Manooch and Hogarth, 1983; FWC-FMRI, unpublished data).

Wahoo are an important recreational and commercial species in Florida waters. In the recreational fishery, a total of 441,385 pounds of wahoo were landed on the Florida Atlantic coast and 92,620 pounds were landed on the Florida gulf coast during 2000 (NMFS, Fisheries Statistics and Economic Division, personal communication). A total of 55,003 pounds of wahoo were landed by the commercial fishery in Florida waters during 2000 (FWC-FMRI, 2001). The majority of commercially caught wahoo are landed as incidental catch from fisheries targeting other pelagic species (SAFMC, 2000).

A total of 61 wahoo were collected for mercury analysis from offshore waters of the Florida Atlantic and Gulf coasts. The majority of fish were collected in offshore waters adjacent to the Indian River Lagoon (n = 30) and offshore waters adjacent to Apalachicola Bay (n = 16). All wahoo sampled were of harvestable size, ranging from 845 to 1,338 mm SL. Total mercury levels for individual fish ranged from 0.04 to 1.40 ppm. The mean total mercury level for fish collected offshore from the Indian River Lagoon area was 0.27 ppm (median = 0.23 ppm). Eighteen percent of all wahoo tested from Florida had total mercury levels greater than or equal to 0.5 ppm, and no wahoo contained total mercury levels greater than 1.5 ppm. Analysis of wahoo from offshore waters adjacent to the Indian River Lagoon indicated a significant positive correlation between total mercury level and fish length (P < 0.0001).

In January 2003, based on additional data from south Florida, DOH issued a health advisory recommending limited consumption of wahoo from Florida Keys/Florida Bay (DOH, 2003).

References
Adams, D.H.; McMichael, R.H., Jr.; Henderson, G.E. 2003. Mercury levels in marine and estuarine fishes of Florida 1989-2001. FMRI Technical Reports TR-9. St. Petersburg, Florida. 58 pp.

Brown-Peterson, N. J., J. S. Franks, and A. M. Burke. 2000. Preliminary observations on the reproductive biology of wahoo, Acanthocybium solanderi, from the northern Gulf of Mexico and Bimini, Bahamas. Pp. 414-427 in Proceedings of the Gulf and Caribbean Fisheries Institute 51st Annual Meeting, St. Croix, USVI.

DOH (Florida Department of Health). 2003. Florida Fish Consumption Advisories. Tallahassee, Florida. 7 pp.

FWC-FMRI (Florida Marine Research Institute). 2001. Catch Rate Summary 1990-2000. FWC-FMRI Marine Fisheries Information System. St. Petersburg, Florida. 46 pp.

Hogarth, W. T. 1976. Life history aspects of the wahoo Acanthocybium solanderi (Cuvier and valenciennes) from the coast of North Carolina. Ph.D. Dissertation. North Carolina State University, Raleigh, NC. 107 pp.

Manooch, C. S., III, and W. T. Hogarth. 1983. Stomach contents and giant Trematodes from Wahoo Acanthocybium solanderi collected along the South Atlantic and gulf coasts of the USA. Bulletin Marine Science 33(2): 227-238.

SAFMC (South Atlantic Fishery Management Council). 1998. Dolphin/wahoo workshop report. South Atlantic Fishery Management Council, Charleston, South Carolina. Unpaginated.

SAFMC (South Atlantic Fishery Management Council). 2000. Draft: Fishery management plan for the dolphin and wahoo fishery of the Atlantic, Caribbean, and Gulf of Mexico. SAFMC. Charleston, SC. 218 pp.

Wollam, M. B. 1969. Larval wahoo, Acanthocybium solanderi, from the straits of Yucatan and Florida. Florida Department of Natural Resources Marine Research Laboratory Leaflet Series 4(12):1-7.

* Prior to July 1, 2004, the Fish and Wildlife Research Institute (FWRI) was known as the Florida Marine Research Institute. The institute name has not been changed in historical articles and articles that directly reference work done by the Florida Marine Research Institute.