Highlights of Shawn Crouse’s Presentation
to the RVTA General Membership on March 17, 2011
By Jim Saccento
Results of the 2011 Gill Net Survey
At the RVTA’s March Meeting we were pleased to have as guest speaker, Shawn Crouse,
Principal Fisheries Biologist for New Jersey. Shawn addressed an audience of about 70 RVTA
members and presented an informative slide presentation, discussing everything from NJDF&G’s
stocking plan, to the food chain at Round Valley Reservoir. Unfortunately, due to space
constraints, we could not run this story in the April newsletter.
Fall 2010 Lake Trout Gill-Net Survey- During a period beginning October 26 thru November 10,
NJDF&G conducted its 18th annual gill-netting in Round Valley Reservoir in an attempt to build a
continued database of Lake Trout and their forage. The net was deployed in 3 positions along the
Northeast shore, and 1 position near the South Dam. 180 Lake Trout were caught during the
period. The largest being a 19+ pound, 36.7 Inch female.
The following results were evident in the slide graphs that Shawn displayed. Lake Trout seem to
be thriving, with head counts being at their all-time high during the most recent 3 years of gillnetting. The count has been constantly climbing since hitting a low point in the 2001.
Even though a few whoppers were netted, about 80% of the 180 Lakers netted fell in the 15 to 18
inch size class. 61 fish fell into the 20-24 inch category and only 11 of the 180 measured over 24
inches. The prior year’s (2009) Gill Netting Survey indicated a similar trend.
Additionally, When compared to expected growth trends in 29 other lakes sampled, Round Valley
Lakers tend to grow in size as expected until they are around 10 years old, after 10 years, their
growth seems to level off, with the typical 10+ year old fish not exceeding 24 inches. The giants,
over 28 inches are exceptions.
Adjusting for the Imbalance-Studies indicate that there are far too many Lake Trout in the 20 to
24 inch class, possibly over taxing the available forage in the Valley. To counter this, since 2008,
the NJDF&G has instituted a 3 fish creel limit of 15-20 inches. A catch and release slot of 20 to 24
inch fish, and only one fish allowed in the 24 inch and up class. For 2012 the state is considering
increasing the creel limit of the 15-20 class to 6 fish per day, eliminating the protected slot, and
allowing one fish over 24 inches.
Evidence indicates that opening the Fall spawn closed period would NOT have a significant
impact in altering the Lake Trout growth issue.
The Food Chain-We all know how clear and clean Round Valley’s water is. It’s great as a water
supply, but falls somewhat short in providing a balanced food chain. Phytoplankton, microscopic
plant organisms, are eaten by microscopic animals called zooplankton. Zooplankton, in turn,
provides a food source for fingerling trout, bass and small bait fish. The level of these 2
organisms in Round Valley as compared to many other lakes, is significantly lower for some
uncertain reason.
The occasional pumping of river water into Round Valley only seems to raise the nutrient level
and plankton count only slightly during the immediate season that the pumping occurs, however
the levels rapidly fall off by the next year. The last 2 pumping events took place in the spring of
2003 and 2006. Another pumping will occur in the Spring of 2011 to replenish the draw-down
caused by the 2010 drought. Therefore, we could again experience a temporary spike in nutrients
in the 2011 season. One could ask, “why don’t they drawn down and pump water every year”.
Well, first of all, it’s expensive, and besides, pumping in river nutrients defeats the primary
purpose of Round Valley as a “clean” water source. So don’t count on any extra pumping just to
increase nutrients. Another thing that has to be considered, each time we have a 10 or 12 foot
draw-down because of a Summer drought, much of the shallow water vegetation dies off. This is
a prime habitat for zooplankton and newborn fish to hang out in. With that cover lost, young fish
become easy prey for adult fish come dinnertime.
The State and RVTA has stocked Herring into the reservoir over the past few years, however, it
has not had a noticeable positive impact on the fishery. A private 4-year survey conducted by
RVTA member Mike Kalinchock indicated that out of 278 assorted trout caught between 2006-10,
only 23 fish had evidence of Herring in their digestive tract. Are the Herring not surviving in great
enough numbers to make a dent as a food fish? There is also some concern that large schools of
Herring may also over-eat the limoted zooplankton, further upsetting the natural food chain.
Because of the poor plankton levels in Round Valley, stocked Herring may not survive or
reproduce in any discernable numbers. Herring are also ferocious feeders of other fish’s eggs,
and there is some evidence that they also excrete an enzyme called thiamase that may stunt the
growth of other fish embryos. Some anglers recall days gone by when abundant schools of
Herring filled the reservoir. That ended in the late 90’s. Perhaps during those early years, Round
Valley had more natural nutrients to support the plankton, baitfish and Trout. Don’t forget, Round
Valley’s basin was formerly nutrient-rich farmland. Is Round Valley just getting too clean to
naturally feed everything that swims in it?
Other Contenders as Food Fish-The NJDF&W has explored other small fish as possible food
sources. The best candidate seems to be the Golden Shiner. These hardy little fish can grow to 8
to 12 inches under certain conditions. Golden Shiners are a fairly common baitfish that I’m sure
many of us have bought from Steve when Herring were not available. Shiners are a lot less
expensive than Herring, therefore, they can be stocked in greater numbers. Shawn Crouse feels
that adding this species to Round Valley offers the least risk to upsetting the balance and may
provide the most benefit. At Shawn’s recommendation, RVTA stocked 20,000 Golden Shiners in
May 2011.
Overall-Sure, Round Valley has issues maintaining a perfect habitat, but, where else this far
south can one have a chance at catching a truly trophy class trout so close to home. And, don’t
forget the Largemouth and Smallmouth Bass and other pan fish that can add to a day’s catch.
Round Valley is truly a jewel that we can all enjoy.