Fish Can’t Walk Around Dams

Initiatives | News | Raritan River Initiatives | Water Quality

Dr. Olaf Jensen (Rutgers Marine and Coastal Sciences) was one of the guest speakers at the August 10, 2017 riverside ceremony to mark the commencement of removing the Weston Mill Dam (see related post).  Dr. Jensen spoke about the resilience of fish species but noted that fish can’t walk around dams.  Following is the full text of Dr. Jensen’s remarks:

“As a community, we in New Jersey have long tended to ignore our rivers.  Instead of facing the river with café terraces and grand promenades, we turn the backs of our buildings to it or build highways along it.  At worst, we’ve allowed factories to spew toxic chemicals into the water.  Or at best, we designate the floodplain as swampland and ignore it.

“And many of us have assumed that all this neglect has killed our rivers.  When I bring students on field trips to pull nets through the Raritan, many ask if it’s safe to touch the water.  When I ask what they expect to catch, they say shoes and tires.  And in truth we get a few of those.  But we also pull in nets full of copper-colored quillbacks, and five species of native bass and sunfish.  In total we’ve caught more than 20 different species of fish right below the 287 bridge.

“It turns out that while we’ve been ignoring our rivers, many fish species have been ignoring our insults and thriving.  Fish are remarkably resilient.  In the Gulf of Mexico, a year after the Deepwater Horizon oil spill, populations of almost all fish were right where they were before the spill.  Fish can handle many insults.  What they can’t do is get out of the river and walk around dams.

“Which is why dam removal is so critical to the recovery of our rivers.  Migratory species like shad and river herring once ranged up and down the Raritan and Millstone.   And with them, they brought critical nutrients from the oceans within their bodies.  They provided food to eagles and herons and after they died to aquatic insects and other invertebrates.  But when dams came in, they lost access to most of their spawning habitat.  And despite efforts to protect them from fishing and other threats, they’ve largely failed to recover.  What’s needed is what we’re celebrating today: the removal of dams and the restoration of free-flowing rivers.”

Professor Jensen and his team are presently conducting research on the effectiveness of the fish ladder at the Island Farm Weir at the confluence of the Millstone and main stem Raritan rivers and maintains the Raritan River Fish Cam.  For more information about Dr. Jensen’s research visit: