A look at factors and environmental influences on migratory fish species.
If you live in the Northeast, and fish any of our saltwater species, then hopefully you realize that all of our species are migratory in nature as these fish are always moving due to our seasonal changes. Most fish have optimal conditions for breeding, feeding, and positioning, but the world is not ideal, but rather they prefer a “comfortable” range.
Species of fish observe specific cycles in daily movement, feeding, spawning, and migratory movement with the successful ones surviving year after year. These patterns have been occurring over millions of years and are affected by a wide range of factors from, especially for coastal species in the saltwater environment. Each factor influences and contributes to behaviors of particular species and can impact an angler’s success. For instance, a constant southerly wind can shut down ocean fisheries due to drops in water temperature and stirred up bottoms.
Temperature plays a large role in the behavior of many species from mollusks and crustaceans to fish and marine mammals. Water temperatures have a huge impact on our coastal species as they live in the briny aqueous environment which, especially for cold-blooded animals, depend on specific degree ranges to exist. As the mercury begins to slowly climb each year as it has for the last 150 years, migratory changes and altered behaviors are becoming more apparent to coastal fishermen.
Take a look at the bull shark for example, a species which prefers the warmer coastal climes of our southern states. Over the course of the last 50 years, the bull shark has been slowly migrating northward with new ecological areas opening up due in part to fish stocks pushing northward due to temperature changes. The northern parts of Florida used to be the main pupping grounds, but bulls have moved over 500 miles north and now are regulars pupping their offspring in the Pamlico Sound in North Carolina. Although bulls have been visitors to the Chesapeake Bay area over decades, there is increasing evidence of the push further north and pupping occurring in the rich waters of the Chesapeake. Last fall, quite a few large bulls were caught around Barnegat Inlet in the direct shadows of “Old Barney”, which could be a harbinger of things to come for many of our species.
Other species have shown similar changes in migration, commercial clam boats are having to fish further and further north as ocean quahogs and surf clam larvae slowly migrated northward in preference of cooler water over the past 20-plus years. The list is endless, so changes are around the corner, if not here already. Regardless of the factor (winds, salinity, temperature, tide, etc.), anglers need to observe and understand the pattern of changes as it will increase our angling opportunities and effectiveness on the water.
Familiar Variations
There are an incredible amount of variables that interconnect predator and prey behaviors within the saltwater environment. Our coastal waterways are much more dynamic than the relatively static systems such as ponds or lakes. Fluctuations or changes in the saltwater arenas vary hour to hour, even minute to minute: tides, temperature, salinity, turbidity, and water velocities are just a few factors that influence bait and predator movement within the system. In addition, daytime and night-time changes, called diel variations, will also impact the movements and behaviors of organisms. Zooplankton will move to different depths during day and night with baitfish feeding on these microscopic foundations of the food web. Predator species can be found close by awaiting unknowingly baitfish which are preoccupied with feeding on the plankton. All of this coordinated biological dance being caused by the rise and fall of the sun.
The moon of course also has great influence on our oceans with daily tidal impacts as the moon runs through its phases. The tide has a tremendous impact on the migration and feeding habits of all species in our waters, both vertically (tidal height) and horizontally (tidal current). For example, summer flounder will position themselves facing the direction of the water during the ebb or flood tides, as the current slacks fluke will cease feeding and re-position themselves for the next tide cycle. Stronger currents during a full or new moon will have the fluke’s feeding window shortened and the opposite occurring on the quarter moons.
Other species such as striped bass increase feeding activity during the peak velocity flows of the tides as baitfish have a higher probability of being caught in the currents. As the current flows decrease in speed, less baitfish become available for feeding and striper activity drops off dramatically. On certain moon phases, full and new, currents will be stronger as the moon and sun’s gravity combined will move more water. Stripers may feed in larger windows with the favorable currents, while the quarter moon’s slower currents will have
Winds and temperature changes go hand in hand as these two will also have a powerful impact on feeding behaviors. The interplay of the winds, the earth’s rotation and Coriolis effect can push or pull water from the surface and below. Northerly or northeast winds tend to bring in warmer water as the water moves at a 90-degree angle from the direction of the wind. Offshore species and bottom-feeding fluke tend to bite much better in these conditions as anglers should note.
The dreaded south wind does the exact opposite as it pushes warmer surface waters offshore leading to upwelling events which bring much colder water inshore. The colder bottom temperatures will instantly demolish a good summer fluke bite, but not all is lost. The cold ocean water can lead to mid-summer striped bass bites along the inlets and jump start lackadaisical fluke in the summer bay bath water.
Unfortunately with ocean temperatures slowly rising, longer duration and stronger windy days become more frequent as do the severity of coastal and tropical systems. As anglers, we need to embrace and understand the changes if we want to be better fishermen in the future.
University Accepted
Rutgers University researcher and foremost scientist on the Mid-Atlantic bight, Dr. Kenneth Able, has seen consistent temperature increases since the 1970s for Great Bay as well as changes in migratory patterns in a variety of species. He details an extraordinary amount of scientifically backed information on these changes in his book, Beneath the Surface, which is a great read in the offseason for anyone interested in the Mid-Atlantic bight. Researchers have found that summer flounder spawning offshore with the bulk of the spawn occurring 30 to 60 miles offshore during the early to late fall. The larval offspring work their way back to New Jersey’s estuaries and bays affected by ocean and wind-driven currents, temperatures, and more.
Many species, in addition to flounder, spawn inshore and offshore as far north as the Grand Banks and south to North Carolina. In the last 30 years, the Rutgers University Marine Field Station (RUMFS) has tracked the influx decreased in northern species, while the influx of southern larval species have increased consistently. There may a correlation to why summer flounder, which prefer cooler water, tend to more numerous and bigger in size as one moves higher in latitudes.
The Rutgers University Marine Field Station (RUMFS) sits at the junction of the Inter-coastal Waterway (ICW) and Little Egg Inlet and was a former US Coast Guard station. The facility has been used by Rutgers since 1972 and operates year-round with research being conducted nearly 70 hours a week by coastal scientists and marine biologists. It stands today at the end of Great Bay Boulevard, often referred to as Seven Bridges Road in Little Egg Harbor.
One interesting note about summer flounder larvae studied in the Great Bay region by Dr. Able and his team, is how quickly these fish mature. “These larvae, which come in about one-half inch in length will start growing very fast beginning now, as the water temperatures warm, and could reach about 10 inches by September,” Dr. Able said.
Baitfish & Gamefish
Baitfish tend to lead the charge as certain migratory cues will initiate movements and longer treks in search of much needed calories or spawning opportunities. Menhaden, a primary baitfish in the Northeast, has begun to shift its migration pattern moving farther northward, staying longer, resulting in reduced or broken up movements during the southern migration. In the past 10-plus years, many Northeast anglers have noticed a big change with more and more bunker staying offshore as they transit past our area. With the offshore route, striped bass are increasingly found well past the 3-mile federal fisheries line. In fact, it’s not uncommon to find acres of striped bass 15 miles or more off our shores as bass are going to go where the food source is best.
Mullet, another Atlantic Coast baitfish, known for the traditional “mullet” run which surfcasters love has generally occurred in September and October. But the run has also been affected by the changes in climate temperatures as scientists are seeing this fish delay their migration or leave on “freak” cold fronts during the early fall. These fractured runs make it more challenging for gamefish to find and feed, which consequently produce less angling opportunities.
On the gamefish front, the changing bait migrations often throw a curveball into coastal gamefish which have little wiggle room with the need for the mandatory calories. Gamefish will tend to feed on a variety of species, especially if their higher preference choices aren’t present. In recent years, our bays in New Jersey have seen an increased number of spot as their presence has been reduced in the Chesapeake Bay area due to movement north for cooler waters.
But for anglers, the biggest question is “How does this affect our fisheries?” Summer flounder which begin exiting our bays sometime in July can be better targeted, especially the keeper specimens, with livelined spot as these will better match the hatch. In addition to live bait, bulkier artificials resembling spot may prove to show better promise in catching these summer flounder.
Many have heard of the old angling adage, “10% of fishermen catch 90% of the fish” which rings true with many anglers. Regardless of type of water, the top fishermen do something grossly different from the fishing masses; they observe, pay attention, adapt, and change their fishing strategies to the changes or patterns which occur within the system. All serious anglers, and those who want to improve, should strive to do this as this will greatly increase the connection rate of the hook to the fish’s mouth.
Remember, observe, adapt and change your fishing strategies on your next piscatorial pursuit – tight lines!
