Fish are economically and ecologically important in the Gulf of Mexico, yet their stocks are decreasing due to overfishing. One major way that we can help protect fish is to protect the habitats where they reproduce. But in order to do that, we first have to find out where they reproduce. One way to find these spawning habitats is by using floating fish eggs.

Before setting up projects focused on reef fishes, like grouper and snapper, we needed to know if eggs from shallow water fishes stay in the shallows or if the eggs move into deeper waters as they float.

Fish eggs can be found in most surface waters, making them easy to collect with a plankton net. However, these eggs are usually clear balls the size of the tip of a pencil, making them difficult to visually identify down to species level. To solve this problem, we use a laboratory method called DNA barcoding. DNA barcoding allows us to look at the genetic material of each fish egg to figure out which species it belongs to. Each species has a unique DNA signature, just like how each product at a grocery store has its own unique barcode.

Using DNA barcoding, we found that most shallow water fish eggs stay in shallow waters. This information will help us plan future fish egg collections to help inform fisheries managers where and how much these shallow water species are spawning.