Major Dolphin Recoveries in the Tropical Atlantic

Another Dolphin Goes the Distance (Again!) Last month we reported on a major recovery that occurred north of Arecibo, Puerto Rico, in December.  You can read a detailed article about that recovery by clicking here.  This month we are excited to report that Danielle and Daryl Gustafson of Big Pine Key, FL, added another major recovery for the DRP, but this time it was north of St. Thomas, USVI.  The fish was recaptured by Eric Estrada during a charter run by Captain Colin Butler, owner of Fish Whistle Sport Fishing Charters.  This is the first international recapture from Florida to the north coast of the USVIs for the DRP and the second recovery in the northern portion of the U.S. Caribbean in the past three months for the DRP.  Is this a pattern?  Two recoveries do not point to a pattern but the recoveries are intriguing for a couple of reasons.  First, the most obvious observation is that both fish were tagged off the Florida Keys in nearly the same location (only 20 miles between release locations) and recaptured north of the continental shelf break that separates the USVIs and Puerto Rico from the Caribbean Sea.  Secondly, these recoveries are the first for the DRP since the program began in 2002 that moved from the Keys to this area.  In the case of the most recent recovery, the fish was at liberty for 210 days and grew 14″ or at least .46″ per week before being recovered.  While the time at large is similar to the December recovery (a difference of 12 days), the growth rate of the fish involved in the most recent recovery is substantially slower.  In the case of the December recovery, the fish weighed 27 pounds when recovered.  Looking at thousands of length-at-weight records, a dolphin that weighs 27 pounds is estimated to range between 44” to 47” depending on the gender (which was unknown in the December recovery).  Therefore, we estimate the growth of the fish recovered in December to range between .70” to .98” per week, or 35% to 54% faster than the most recent recovery.  The biggest caveat with this comparison is the fact that the December growth rate was estimated based off measurements that were estimated.  However, even when we compare the growth rate of the fish involved in the most recent recovery to only those recaptures that have occurred throughout the history of the program where sizes were measured upon release and recapture, the growth rate is still substantially slower for this fish.  Could this have been a pompono dolphin which are known to be smaller than their common dolphin cousins?  The Gustafsons did not note that this was a pompono upon release (and they tagged 9 other individuals on that particular day), and when recaptured, Captain Colin Butler did not notice anything peculiar about the fish but did note that it was a male (it was noted a male upon release, too).  Male pompono also develop a blunt forehead but it is not as pronounced as the common dolphin.  Because of this observation, we lean more toward this recovery being a common dolphin, but because a photograph was not taken of the fish before it was re-released with the tag, we are not 100% certain.  Take home message: please take photos of fish that are recaptured