Introduction:

Today we will be talking about how to become a DNA Detective. First, let’s go over the importance of understanding where fish are located. Many people in the world (about 17%) rely on fish as their main source of protein. Think about how many people you know that eat fish, maybe even you! In order to protect fish, we need to protect all of their life stages. Fish usually start off as eggs (the size of the tip of a pencil), hatch into larvae (baby fish), then keep growing until they are juveniles, and finally, a full-size adult. As they grow, they can use different areas of the ocean (estuaries, open ocean, coasts). There are thousands of fish species in the world and we are still learning about how they grow and where they live. The act of protecting fish in their environment is called fisheries management.

Collecting fish eggs:

We collect the fish eggs in the surface waters using big plankton nets with tiny holes, so only water can pass through and the plankton get stuck in the jar at the bottom of the net. Plankton are microscopic organisms that live in the surface waters and go with the motion of the ocean. Fish eggs are part of these plankton. Most fish are broadcast spawners, meaning they release their eggs into the water where they float to the surface like mini balloons, making them easy for us to capture.

Picking the eggs out of the water sample:

Each fish egg is hidden in the water sample filled with other plankton, so we have to go for an egg hunt using a microscope to pick out each one out. We use forceps to pick them up. It is like picking up a mini water balloon with chopsticks. At this point, you'd think we could identify the eggs using their physical features, but most fish eggs look exactly the same, so we have to use their DNA.

Lab work! Your turn:

Now that the eggs are separated, we take them to the lab where we extract the DNA. If you are interested in learning about how DNA is extracted, watch this video. DNA is genetic material found in every living thing, made up of 4 base pairs, or letters (ATGC). You can think of DNA codes like barcodes at the grocery store. Each item at the store has its own code of numbers, while each organism has its own code of letters. We can use DNA as a barcode to identify the fish species that each egg came from.