The definition varies a bit depending on where you look but pelagic can be defined as relating to open waters or living in water away from shore and the bottom. Using both descriptions it’s easy to think of giant tuna species that patrol the deep open ocean far from shore but its more complicated than that.
All of the open ocean water except for places near the bottom and near the shore are included in the pelagic zone. This zone begins where the coastal zone ends with the low tide mark being the defining line between the two. This makes the pelagic zone much closer to shore and includes more fish species than most people assume. To put everything into perspective, the pelagic marine environment is the largest aquatic environment on earth and holds 11% of the world’s fish species.
The term “pelagic species” is commonly used when referring to open-ocean predators but pelagic fish species can be found in both freshwater and marine environments. Small freshwater pelagic fish are being evaluated as a potential food source for undernourished communities in Africa.
Because the pelagic zone comes so close to shore redfish, speckled sea trout, amberjack, and even cobia are considered pelagic species. Popular sportfish like tuna, marlin, sailfish, and swordfish live farther offshore in the open waters over the continental shelf and are all pelagic species as well.
Not all deep-sea fish are considered pelagic with some fish species living too deep in the water column. Although swordfish can live in depths of up to 2000ft they are still pelagic species while several species of spiderfish live on the seafloor and are considered benthic fish.
The fish species within the pelagic zone have a variety of environmental factors to deal with just to be able to breathe let alone find food. Life in the pelagic zone is controlled by oxygen levels, sunlight, structure, temperature, and available nutrients in the water. Each species is different and prefers slightly different parameters that allow them to utilize the same waters but not always at the same time. Wahoo for example prefer water temperatures between 70-80 degrees while kingfish inhabit cooler water around 60-70 degrees. While these fish will occasionally overlap they generally don’t have around long enough to compete for the same food sources.
Usually in a conversation between anglers, the term pelagic is used without distinction. With such an abundant category of fish spread out over a vast area, the terms coastal pelagic and oceanic pelagic become necessary to prevent confusion.
Coastal pelagic species are defined as fish living in waters less than 655 feet deep which means they are typically above the continental shelf. Some of the most popular coastal pelagic species include wahoo, blackfin tuna, mackerel, redfish, and speckled sea trout. Although these fish migrate and may cross over the continental shelf they are considered coastal because their natural range and feeding grounds are within the coastal pelagic zone.
Oceanic pelagic species pick up where the costal pelagic zone ends and contain fish species that are more commonly referred to as pelagic species. Oceanic pelagic species are usually found below the continental shelf where sunlight is hard to come by. These fish generally grow larger and are some of the popular sportfish in the world including swordfish, yellowfin tuna, bluefin tuna, and sharks. Many of these species are also considered highly migratory species and cover long distances in search of spawning grounds or food.
Some of the most popular deep-sea sportfish are both pelagic species and highly migratory species. While redfish are technically a pelagic species they are not considered a highly migratory species but bluefin tuna are pelagic and highly migratory.
The difference is in the distance these fish travel throughout their life. Bluefin Tuna will travel from California past Hawaii and end up in Japan, thousands of miles away from where they started. Redfish on the other hand will pretty much just stay put within their typical range. Even though redfish do migrate from deeper waters into shallow estuaries this is nowhere near highly migratory compared to the thousands of miles a tuna may travel in a calendar year.
Pelagic fish species make up the vast majority of sportfish we all love to catch. From redfish migrating in estuaries to swordfish feeding in the dark depths past the continental shelf, the pelagic zone is huge. With all of this information about the species and environment that make up the pelagic zone, you can start to build a better understanding of the forces at play when you head out on your next trip. If you know what is going on in the water you will find more success each time to wet a line.