Hard Clams Getting Busy in the Bay

​Sensual things are about to happen beneath the murky surface waters in New York Harbor. Hard clams are getting ready to spawn.
 
As air and water temperatures begin to warm, the next generation of chowder clams, littlenecks and cherrystones are about to be born. Although this natural event is not as exciting to observe as coral spawning in the Great Barrier Reef, it’s proof there are rich natural resources thriving in New York Harbor frequently unnoticed by many folks.
 
Clams are commercially important bivalves. So much so that the hard clam fishery in the harbor comprises about 50% of New Jersey’s hard clam landings, according to the New York and New Jersey Harbor Estuary Program. Of course due to ongoing poor water quality, all clams from the harbor currently must be cleansed before they are sold to market. In New Jersey this is accomplished through depuration in two plants in Monmouth County.” One plant is located in the Borough of Highlands and the other in the Borough of Sea Bright. 

​Don’t know what a hard clam is? You probably have seen or tasted many in your life and didn’t know it. Hard clams, also known as quahogs, are one of the most abundant shellfish species in local estuarine waters. If you have ever walked along the edge of the bay, you have most likely stepped upon a hard clam. They are tough clams with thick, rounded shells that can grow to 4 inches or longer.
 
A hard clam’s most noticeable feature is the streak of deep purple within the shell’s interior. It’s the only clam in the harbor with a splash of purple inside. Coastal Native Americans regularly used the shells of hard clams to make wampum, white and purple shell beads used in traditional ceremonies as a system of recording important events.
 
Starting in May, hard clams or quahogs produce gametes or reproductive cells. When water temperatures around Lower New York Bay reach above 68 degrees F, watch out! Billions if not trillions of eggs will be released and fertilized in the water column. One single female clam can release 16 to 24 million eggs per spawn. Hard clams will spawn several times between May and October or when water temperatures are between 68 to 73 degrees F.
 
Once eggs have been released and fertilized, free-swimming larvae will grow for a week to 24 days. During this time, the clam larvae will develop a tiny foot that will be used to crawl and “investigate” the bottom of the bay before finding a sandy or muddy home to settle. When a minuscule clam has found a home to inhabit, it will anchor itself by thin threads secreted from a gland on its slimy foot. The settled clam will then slowly metamorphose into a juvenile clam, developing siphons, a digestive system, and gills. It will stay in one place for the rest of its life, in the shallow salty waters of Lower New York Bay.

A Hard Clam density map on the New Jersey side of New York Harbor

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​But the fun doesn’t stop here. Researchers at the Smithsonian Marine Station tell us that approximately 98% of all juvenile clams begin life as males; however, with increased age and size, sex ratios in the population even out, and approximately half of the males later change to females. It’s a complicated life even for a clam.
 
While many hard clams typically have a life span of 4 to 8 years, some can be long-lived creatures of the bay.  Sometimes a single clam, if not eaten or harvested, can live for more than 30 or 40 years.
 
Many don’t make it though. Hard clams are near the bottom of the food chain, just about everything loves to take a bite out of a clam, from fish to crabs to gulls.
 
What do clams like to eat? Like many bivalves, hard clams are filter feeders. They use their gills to filter food particles from the water. The clam will take in water, plankton and nutrients through one siphon sticking out of its shell, and from another siphon it will eject unused water and waste, but in this case the waste is cleaner water. Thus the name “filter feeder.” Bivalves act like aquarium filters, cleaning up waters as they feed. Certainly a very important activity in a very turbid estuary.
 
For most folks, though, clams are all about tasty coastal cuisine. Littleneck clams are often served raw, on the half shell. Cherrystone and chowder clams are served as baked clams and used in dishes such as clam chowder and linguine with clam sauce. Bon appetite!