It all starts with spawning.
Year after year, many fish species make dramatic short-term migrations from their usual home ranges to established reproductive or spawning sites where they form into large-scale high-density mating aggregations. A classic example is the Pacific salmon, which migrates from ocean waters to far away tributaries where individuals find mates, after which they will die.
Successful spawning events during these times mean more fish for the start of the next generation. This means that identifying the places and times when spawning might occur can be very important for managing the future of a fish population. Here in the Gulf of Maine, knowledge of where and when important fishery species like the Atlantic cod spawn (and the identification of new and previously unknown spawning areas) can be an incredible resource for supporting the resurgence of these historic and world-renown fish populations.
How can we go about predicting where and at what times in a gigantic ocean fish might aggregate to spawn? One piece of information can come from satellites, like those managed by the National Oceanic and Atmospheric Association which record information on sea surface temperatures and daily primary productivity. Another can come from ocean bathymetry mapping that serves as a map of the habitat at the ocean floor. Lastly, the Division of Marine Fisheries continually collects information on the status of native fish species including their seasonal abundances in Massachusetts waters.
Linking patterns in the ocean with shifting movements of fish populations over time can be difficult, but it can yield important results. Your goal is to identify conditions when cod are likely to spawn and use that information to predict where and when cod are likely to spawn in the future.