Study Finds 68 Fish Species in Monmouth County Waters Using DNA Sampling

Water samples from Monmouth County beaches, bays, and tidal rivers revealed at least 68 fish species this fall. Community scientists partnered with the Monmouth University Urban Coast Institute to gather samples that were analyzed for environmental DNA.

Volunteers began gathering samples in September. They received equipment and instruction from university researchers first. On Nov. 20, participants arrived on campus to discover the study method and what scientists found.

Marine organisms shed eDNA into the water around them. This DNA carries signatures called metabarcodes that identify species. Endowed Professor of Marine Science Jason Adolf explained these materials break down within about a day. Detection means the species swam through those waters within hours.

"It's like barcoding at the supermarket, where instead of the person having to find the price tag for each item, you just scan it and the computer knows what it is," Adolf said, according to Monmouth.edu. "We have a database for all of the barcode sequences of fish, marine mammals, turtles, and humans, and when we detect it in the natural sample, we can tell that a fish was there, and to some extent, how many of the fish were there."

Volunteers gathered samples at 22 stations from the Manasquan Inlet to the Raritan Bay. Mummichog appeared most often in estuaries. Atlantic silverside came next, followed by Atlantic or Gulf menhaden.

River herring's metabarcode looks almost identical to Atlantic menhaden. Scientists can't tell them apart. If the possible river herring detections were menhaden instead, it would rank as the second most-detected fish.

Ocean waters told a different story. Tautog appeared most often, followed by menhaden, black drum or spot, and river herring or menhaden. Scientists counted shark and ray species separately. Sand tiger shark appeared most in estuaries, while clearnose skate and smooth dogfish dominated ocean samples.

An Asbury Park beach showed the highest species count at 27. A beach near the Shark River Inlet in Belmar had 24. The Raritan Bay locations showed fewer species than southern estuaries.

UCI Resilience and Outreach Project Lead Richard Kane said the data will establish a baseline for future comparison. Scientists plan a second sampling round during summer months.

"Each species plays a very important role in the function of their ecosystem, and as biodiversity decreases, ecosystem function decreases," Kane said. "It's important that we monitor biodiversity because ecosystem function — the working of the planet — is reliant on there being biodiversity and allowing these functions to continue."