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(Credit: Fish Guy Photos)

If you live in the Riverhead area, you are undoubtedly familiar with a fish known as bunker. Every spring, for thousands of years, this schooling fish has flooded into local estuaries where their arrival has been welcomed by a countless number of organisms. In recent years however, this ritual migration has often ended disastrously for the bunker and a nauseating mess for town residents. 

Bunker, also known as Atlantic menhaden, are members of the herring family that range from Nova Scotia to Florida. Growing to fifteen inches in length, they reach sexual maturity by the age of three. Spawning takes place during the winter months in the offshore waters located between the Carolinas and New Jersey. After spawning, they migrate to inshore bays where they will spend the spring and summer feeding before once again returning offshore in the fall. Newly hatched bunker larvae drift the ocean on currents that eventually bring them inshore by late spring/early summer.

While schools of bunker can be extremely dense at times, they are not easily caught by anglers that use standard fishing techniques (i.e. baited hooks or a lure). This difficulty in catching them is due to the fact that they feed exclusively on plankton (microscopic plants and animals). Swimming with their mouth open, they strain plankton from the water with the use of their modified gill rakers.

By feeding on plankton, they serve as a vital link between the energy created by phytoplankton to those organisms that are higher on the food web. As one of the most important forage species found on the east coast, they are preyed upon by a wide variety of predators such as gulls, osprey, bluefish, striped bass, tuna, sharks, dolphins and whales, just to name a few.

Although bunker is not harvested as a food fish, it has still been a fish of great importance to man. Early Native Americans referred to them as munnawhatteaug, which means “that which manures (fertilizes).” They would till bunker into the soil to fertilize corn crops. By the late 1800’s, menhaden oil began to replace whale oil as the primary oil used in industrial processes.

Today, bunker are still heavily fished for in order to meet an ever growing demand for this oily fish. The commercial fishery consists of two parts, a bait fishery and a reduction fishery. The bait fishery supplies bait to commercial and recreational fishermen who target species such as crabs, lobsters, bluefish, striped bass, sharks and tuna. The reduction fishery processes menhaden into fishmeal, oils and dietary supplements. Until recent years, these fisheries were unregulated. In a 2012 stock assessment, it was determined by the Atlantic States Marine Fisheries Commission (ASMFC) that overfishing of bunker was occurring. A decline in their population, could have a negative ripple effect throughout the entire ecosystem, so ASMFC approved the first ever coast-wide catch limit for menhaden. With less fishing pressure and the potential for one mature female to produce 300,000 eggs in a season, the fishery had the potential to rebound in a relatively short time, which it did. The most recent stock assessment in 2015 listed the bunker population as healthy as it is neither overfished nor experiencing overfishing.

If the bunker population is healthy, why are we seeing massive die-offs in places such as the Peconic River and Meeting House Creek in Riverhead? As I mentioned earlier, bunker are a favorite prey for a wide variety of predators. While being pursued by a hungry pack of voracious bluefish, bunker will often be corralled into shallow waters where there is no escape. As more and more bunker are forced into this dead end, they quickly consume all the oxygen and suffocate to death. This is a scenario that has naturally played out for eons, not only in the Peconic but in similar estuaries around the world.

Sadly, many of these fish kills are no longer a 100 percent natural situation. Due to nitrogen loading of our local bays from fertilizers, home septic tanks and dated sewage treatment plants, we are now seeing a spike in harmful algal blooms (HABs). Just like plants, algae utilize nutrients and sunlight to produce their own food and the byproduct is oxygen (a process known as photosynthesis). In the absence of sunlight, the algae can no longer photosynthesize. Instead the algae respire, using available oxygen and giving off carbon dioxide. When one of the HABs coincides during a time when the river is full of bunker, oxygen levels are depleted quickly, especially at night, and the resulting effect is a massive fish kill such as the one we saw in 2015. Additionally, it has been shown that HABs damage the bunker’s gills to the point where even during the day when oxygen is plentiful, they are unable to absorb enough oxygen to survive.

To avoid a repeat of last year’s catastrophe, the town of Riverhead worked with the DEC, the ASMFC and local baymen to harvest bunker from the Peconic River before any potential die-off could occur. According to the town, over 400,000 pounds of bunker have already been harvested from the river this year. As of now, it seems as if this plan might have allowed us to dodge a bullet, but it is only a band aid to a much larger problem. Fixing the problem at the sources will not only prevent future man-made fish kills, but will help return the river to the healthy, balanced ecosystem that it once was.

With a degree in marine biology from LIU/Southampton, Chris Paparo is the manager of Stony Brook Southampton’s Marine Sciences Center. Additionally he is a member of the Outdoor Writers Association of America and the NYS Outdoor Writers Association. You can follow Paparo on Facebook and Instagram @fishguyphotos.