An important component to understanding the biology of an organism is understanding its population structure.  In the case of wahoo, we are studying this relationship between individual fish collected from different parts of the world. 

The first step in this research is to collect tissue samples (usually gill or muscle tissue) from individual fish caught in different geographic regions.  This is generally accomplished by anglers and scientists from around the world. Then, at our laboratory in Davie, Florida, we extract some DNA from the collected tissue.  We then make many copies of a small portion of the extracted DNA in a process called amplification, using a method called polymerase chain reaction (PCR). Having many copies of the DNA allows us to determine the genetic sequence of this piece of DNA using a machine called a DNA Sequencer. We then compare the genetic sequence from one fish to the genetic sequences from other fish. By comparing and analyzing the similarities and differences between DNA sequences from different fish, we interpret how closely or distantly related they are. This allows us to analyze the extent to which genes from individual fish are moved between geographically distant regions, if at all. This creates a foundation upon which many management decisions and future research projects can be based.

We also collect physical and biological data as we make our sample collections. We record the date, location, and water temperature where each individual fish is caught.  We also record weight, length, sex, and reproductive condition of each individual.  By organizing this data, we are able to form some general conclusions about wahoo life history.  We also make this data available to other scientists who use it in their own research projects.

We are also assisting another research team with the collection of wahoo otoliths and reproductive organs.  Otoliths are small bones found in the inner ear of many species of fish (sometimes called “ear stones”). These bones "grow" one layer at a time, on a more-or-less regular basis, somewhat similar to the way rings of a tree are added in layers. Just like the rings on a tree, the layers of an otolith sometimes allow interpretation of the age of a fish. The process is more difficult in fish than in trees, and it has not yet been refined for wahoo, but researchers are working to improve the application.  Otoliths and reproductive organs provide the raw data necessary to conduct age, growth, and reproductive studies.

Recently, we have expanded our study on the movements and distribution of wahoo by deploying pop-up satellite archival tags (PSAT’s), which allow us to monitor the daily movements, depths, and water temperatures of tagged fish for a period of several months, without ever having to recover the fish or the tag.  Read and see more about this exciting new research by clicking on the Satellite Tags link.