The Connection Between Bottlenose Dolphins & Bunker in New York Harbor
A young bottlenose dolphin seen this past summer within a pod of dolphins in Sandy Hook Bay while forging for bunker.
By Joe Reynolds
NY Harbor Nature Blog
​Even though bottlenose dolphins (with their slight upturn in the corner of their mouth which appears to people as the animal is always smiling) is one of the most well known species of marine mammals in the world, many people still don't realize bottlenose dolphins can frequently be seen in New York Harbor during the summer and early fall. Sightings might not always be well-known, but nearly every summer and fall there are dolphins swimming close by.
Typically, Atlantic bottlenose dolphins (Tursiops truncatus), arrive to New York Harbor and surrounding tidal waters between May and June. Many people regularly pay for the opportunity to see dolphins from a boat, but for those lucky folks who are in the right place at the right time many dolphins can be seen from the shoreline, sometimes within 300 feet. An amazing natural experience made even more remarkable as it takes place within sight of New York City, the most developed coastline in America!
Why do bottlenose dolphins swim in the busy waters of New York Harbor? It's all about the food. Over the past several decades, as local waters have slowly become cleaner (though not clean, still more work to do), an abundance of sea life is gradually returning to New York Harbor, such as ospreys, whales, seals and bottlenose dolphins too.
​Atlantic bottlenose dolphins are a group of marine mammals known as cetaceans, which are high level marine predators having, in part, their daily activities related to the location of their prey. They swim to the harbor for the abundance and diversity of food: from weakfish, croaker, spots, and mullets to skates, rays, squid, shrimp, crabs, and clams.
Their favorite food by far is Atlantic menhaden (Brevoortia tyrannus), also known as "bunker." Menhaden is a herring-like fish, often swimming in large schools into the thousands or hundreds of thousands. Menhaden can be found from the Maritime Provinces of Canada to the east coast of Florida in estuarine and coastal waters.
https://en.wikipedia.org/wiki/Atlantic_menhaden
​Menhaden are oily, bony, and inedible to humans, which is why many people have never heard of them. But menhaden are nutrient-packed fish. These little fish are able to convert plankton, algae, seaweed and other omega-3-rich sea plants into a hefty dose of heart healthy fatty acids. It's a critical source of food for many estuarine and coastal species, including Bluefin tuna, bluefish, striped bass, ospreys, bald eagles, whales, and of course dolphins.
It is no wonder that author H. Bruce Franklin has called menhaden "the most important fish in the sea." Bunker is a critical fish in the chain of life.
This past summer several pods of bottlenose dolphins were frequently observed following and feeding on large schools of bunker in Sandy Hook Bay and Raritan Bay, and the Atlantic Ocean near popular Jersey Shore communities including Sea Bright, Monmouth Beach and Long Branch. A pod is usually made up of a couple of mothers, sisters, daughters, young sons, and babies generally taking care of one another. A calf is usually weaned completely at around the time the mother gives birth to the next calf, after an interval of 3 to 6 years.
How could we tell the dolphins were after bunker? They were not alone. Crowds of hungry gulls, terns, cormorants and other seabirds also showed up to devour this oily fish, as well as bluefish. A feeding frenzy was taking place. When you see dimples in the water, like large raindrops exploding on the surface of the water along with silvery flashes of fish and lots of splashes, it's a good sign there is a massive school of bunker down below being attacked. There is no other baitfish more pursed by larger animals than bunker during the summer and fall.
​Dolphins can forage individually or cooperatively by using a series of techniques or tools to capture prey. A lone dolphin may use a sponge or seaweed to help protect its short sensitive beak from sharp rocks, sea urchins, and other things that might hurt it. A bottlenose dolphin may also use its tail to flip an unsuspecting fish out of the water, and then quickly swallow it whole.
One my favorite ways dolphins go about capturing prey is when a pod works together like a highly trained team to locate and seize food. One method is called herding. A group of dolphins will surround a school of fish to pack them in tightly while one by one they take turns swimming through the school to snap up the fish.
Once caught, bottlenose dolphins do not chew their food. They use their many teeth to capture or get a good grip and then will swallow the prey whole.
​It takes a lot of food to satisfy a hungry dolphin. A single dolphin will take in about 20 pounds of seafood a day. That's a lot of fish!
It's a good thing schools of bunker are slowly on the rise. According to the 2015 benchmark stock assessment by the Atlantic States Marine Fisheries Commission (ASMFC), overfishing is not occurring. But this could easily change. Reckless overfishing of menhaden is always a consistent threat.
The Menhaden fishery is the largest on the U.S. East Coast. The majority of Menhaden (80%) are caught by Omega Protein, a $100 million fishing corporation devoted entirely to catching menhaden. The fish are ground up for use as fish oil in dietary supplements, fertilizers, and pet food and animal feed. The remaining 20% of the Menhaden catch is used by commercial fishermen for bait. In the past, the menhaden commercial fishing industry has been pushing for an increase in the catch limit.
Thankfully, after decades of fighting and gridlock, a consensus seems to be emerging among fishery scientists and the fishing industry towards a practicable approach to setting population targets and catches for menhaden. The recent rise in marine life in area waters is the direct result of rules put in place by the Atlantic States Marine Fisheries Commission in 2012 that cut by 20 percent the amount of bunker that could be harvested by commercial fishing. A much discussed continued cap on the menhaden catch is designed to prevent fisheries from overfishing this crucial species, so the menhaden population can rebuild. Unfortunately, menhaden still remain far below their historic numbers in many areas along the East Coast.
Yet, there is some evidence of recovery of menhaden populations in the Mid-Atlantic and for dolphins this means more meals to be found around New York Harbor. This in turn offers many people the unique pleasure of dolphin watching each summer and early fall, before water temperatures turn below 50 degrees.
If you would like to see more bunker and more life in the bay, please consider submitting a comment to the Atlantic States Marine Fisheries Commission, which regulates catches in state waters close to shore from Maine to Florida. Public comment period is now open and we need people to send comments who wish to see more bunker in the water and make sure healthy marine ecosystems along the shoreline thrive.
Please visit www.menhadendefenders.org and give the comment tool a try.
We could really use your help. Thank you!