The Latest on Bonefish Research

December 16, 2004 By: Marshall Cutchin

Dr. Aaron Adams, author of the recent Fisherman’s Coast and co-author of Fly-Fishing for Bonefish, sent us this description of the most current bonefish research being conducted with the help of Bonefish & Tarpon Unlimited, National Fish and Wildlife Foundation, and Turneffe Atoll Conservation Fund. Among the more interesting data: there are atleast two bonefish species to be found in the Caribbean; and Keys bonefish grow at a rate two to five times faster than Belizian or Bahamian fish.

By the way, if you a considering a charitable contribution this year or next, most of the research surrounding important saltwater game species is funded by independent organizations — like Mote Marine Laboratory where Dr. Adams works — which struggle to keep their top scientists employed. If you need contact information you can communicate with us or with Mote Marine directly.

With the support of Bonefish & Tarpon Unlimited, National Fish and Wildlife Foundation, and Turneffe Atoll Conservation Fund, we have been studying bonefish ecology in the Caribbean since 2003, with three major topics of interest: juvenile habitat use, populations genetics, and age-growth. At each step of this research, we are finding new and exciting information.
1) Juveniles. Almost nothing is known about the juvenile life stage of bonefish. We have been sampling for juvenile bonefish (less than 3″) in the Florida Keys and Turneffe Atoll, Belize, to establish which habitats they use and what times of year they use these habitats. We have captured more than 400 juveniles in the Florida Keys – all along medium-energy sandy beaches – but none at Turneffe Atoll. This was a surprise given the high numbers of adult bonefish at Turneffe. Recent results of genetic analysis of the captured juveniles provides clues to why our findings differed so much between the Keys and Belize.
2) Genetics. There are at least two species of bonefish in the Caribbean. Albula vulpes is the species that traditionally has been considered as comprising the regional recreational fisheries. Albula garcia is extremely similar in appearance, but is supposedly smaller maximum size, matures at a smaller size, and inhabits deeper water than Albula vulpes. To date, Albula garcia have only been found in the Florida Keys and Brazil, but sampling effort in other locations has been minimal. It is incredibly difficult to distinguish these species by sight, so we have been using genetic analysis to positively identify our specimens.
We have taken tissue samples from 140 of the more than 400 juvenile bonefish captured in our Florida Keys sampling. 139 of those juveniles were genetically identified as Albula garcia – the ‘other’ species. In other words, we identified the juvenile habitat use (and seasonality) of Albula garcia.
It is assumed that the fishery in the Keys and the wider Caribbean is for Albula vulpes, but that hasn’t been fully tested. It is possible that some of the smaller fish in the fishery are Albula garcia and larger fish are Albula vulpes. This is extremely important information for fisheries conservation and management. To determine the species composition of the fisheries, we have initiated a fin-clip program in the Florida Keys: anglers take a triangle of tissue from the rear portion of the dorsal fin (it will grow back), and we use that tissue for genetic analysis. We are also taking fin clips of bonefish in other locations in the Caribbean.
Even if most of the fisheries are determined to be Albula vulpes, genetic information can be used to determine the extent that bonefish in different locations are related. (Bonefish larvae can float in the open ocean as plankton for up to 72 days, so could potentially be transported a very long distance. This would mean that it is possible that bonefish in Belize and the Florida Keys, for example, are closely entwined.)
3) Age and growth. Genetics are also important in making sure our estimates of bonefish growth rates and ages are accurate and correspond to the correct species. During our research we sacrifice some bonefish and retrieve their ear bones (otoliths), which, when sliced into sections, reveal growth rings (like trees). We can read these growth rings and determine a fish’s age. Some of our research to date has revealed some amazing results:
Fin clips collected at Turneffe Atoll, Belize were identified as Albula vulpes (what we think is the primary species of the Caribbean).
These fish were all approximately 16″ (fork length).
In the Florida Keys, a 16″ fish is 3-4 years old. The 16″ Belize fish were 8-10 years old! So, it appears that Belize bonefish grow 3-4 times slower than Keys bonefish!
Fin clips collected at Eleuthera Island, Bahamas were also identified as Albula vulpes.These fish were all approximately 12″ (fork length).
In the Florida Keys, a 12″ fish is 1 year old. The 12″ Bahamas bonefish were 5 years old! Similar to the Belize results. So, there are more bonefish in Turneffe and Bahamas, but it appears they grow more slowly than in the Keys.
We continue to work with BTU in pursuing additional funds to support this research that will contribute directly to bonefish conservation. We are determined to make this research program a success, and are making progress with each step.