Results show fish staying in Navesink
 
Posted by the Asbury Park Press on 02/24/07 
 
BY KIRK MOORE 
 
TOMS RIVER BUREAU 
 
SANDY HOOK — Dozens of bluefish, striped bass and weakfish implanted with  
electronic tags last summer surprised scientists by staying in the Navesink  
River for an average three weeks or longer, showing how important the suburban  
river remains to marine life, according to preliminary results from those 2006  
experiments.  

  
"What amazed us was how long some of these animals stayed in the system," said  
John Manderson, a scientist at the Northeast Fisheries Science Center's James J.  
Howard Laboratory here. "So even though it's small, a lot of these fish are  
using the system quite intensively." 
 
Researchers with the National Oceanic and Atmospheric Administration team  
captured and released 78 fish after implanting tiny acoustic tags that let them  
individually track each animal up and down the river. They found most of the  
fish tended to congregate in specific areas — often deep, cool holes in the river's midsection  

   — and make excursions up and down the river.
 
"Telemetry is a way for us to at least get a rough, fuzzy picture of what these  
movements look like," Manderson said in a seminar for fellow scientists at the  
lab Thursday.  

  
Researchers think fish movements are governed by temperature, salinity — the  
salt content of water that fluctuates with incoming ocean tides — and a food web  
that "reforms and disappears during one tide cycle," Manderson said. 
 
During 20 small-boat cruises on the river from June to September, researchers  
found fish using what Manderson calls "temporal habitats" in preferred river  
reaches: 
 
Small bluefish tended to congregate in the upper Navesink near Red Bank, where  
there's rich prey of bay anchovies and menhaden. 
 
The mouth of McClee's Creek and other marshland tributaries are gathering areas  
for striped bass, but the stripers show a distinct preference to head downstream  
for cooler waters when river temperatures hit 77 degrees Fahrenheit. 
 
"Bass excursions are incredibly complex," and appeared to be keyed on a  
combination of tides and times of day and night, Manderson said. 
 
Jeff Pessutti, the team's physical science technician, assembled a time-lapse  
computer animation showing one striper's travels over the month of June. The  
fish swam leisurely around the upper and middle river for weeks, before finally  
bolting east of the Oceanic Bridge on June 26. 
 
Looking at the torrents of data collected last summer, Manderson admits he's  
still perplexed trying to make sense of the patterns. "It's kind of insane," he  
joked. "I'm not sure I would want to do it again." 
 
But they will in April, when Manderson and project co-leader Beth Phelan again  
plan to deploy an array of about two dozen buoys and sensors in the river, this  
time concentrating on bluefish and weakfish and looking closer at the marsh  
creeks. 
 
They need help from residents and boaters on the heavily trafficked river, to  
keep an eye out for the buoys. Last summer they lost one every other week, which cost them 18 or 20 hours of data, Manderson  
said. 
 
NOAA scientist Chris Chambers said the team's finding that even frenetic  
bluefish spent an average of 20 days in the river is an important development.  
Before that measurement, the local residency times of fish estimated by  
scientists were sometimes "a myth based on gut feelings," he said.  

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