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Hackettstown Hatchery Broodstock Collection 2004

by Craig Lemon
Hatchery Superintendent

The 2004 spring trap-netting season proved very successful as hatchery and fisheries lab staff collected large numbers of “trophy-quality” fish to serve as brood stock at the Hackettstown State Fish Hatchery. These fish lived up to expectations and produced plenty of eggs for this year’s stocking needs. The fish were netted from various lakes and reservoirs and transported back to the hatchery for egg collection. Millions of eggs from northern pike, walleye and muskellunge adults were taken between March 11 and April 23. Actually, this year’s brood stock collection season kicked off two weeks earlier than 2003 due to the ice melting off Budd Lake (Morris County) in early March.

Highlights this year include the capture of three female walleyes weighing more than 10 pounds each from Swartswood Lake in Sussex County. In fact, one of them equaled the current state record of 13 pounds, 10 ounces!

A muskellunge measuring 50.4 inches was netted from Echo Lake Reservoir in Passaic County along with 25 other nice-sized muskies. Fisheries lab crews also collected muskellunge broodstock from Mercer Lake in Mercer County for the first time since muskies were introduced there in September of 1998. The largest of these muskies weighed an amazing 25.4 pounds -- it attained this size in only five growing seasons!

Following are summaries of the netting activities for each species collected:

Steve Strodel with walleye breeder
Steve Strodel with walleye broodstock

Northern Pike
Three large trapnets and one smaller net were set in Budd Lake on March 11. Water temperatures ranged from 34° to 39°F during the following 11-day netting period. The nets were checked six times over that period, yielding 171 northern pike.

Ed Conley with northern pike
Ed Conley with northern pike

Of these, 149 were transported back to the hatchery where eggs were collected as well as length, weight, sex and age (scale sample) measurements. Such information is crucial to helping biologists evaluate the condition of the lake’s northern pike population. The sex ratio was 4:1, 120 males to 29 females.

Eighteen of the 29 females were spawned and yielded a total of 450,415 eggs. The females averaged 25,023 eggs per fish compared with 31,157 in 2003 and 35,000 in 2002. The decrease in eggs per female is due to the fact that six of the 18 had lost some of their eggs in the nets prior to arriving at the hatchery.

The 2004 Budd Lake numbers proved very similar to the 2003 totals. A total of 171 fish were captured in 2004 compared to 183 in 2003. This year’s males averaged 21.4" compared to 21.7" in 2003, while the females averaged 26.9" compared to 26.4" in 2003. The largest fish was a female weighing 11.1 pounds and measuring 34.2 inches.

All of the adult northerns were safely returned to Budd Lake after egg collection. The eggs hatched after a 10-day incubation period and the fry were grown on a high-protein, dry pellet diet to 7-inch fingerlings for stocking in early July. Regional fisheries biologists have requested a total of 25,000 northern fingerlings for stocking in the following waters: Cranberry Lake (Sussex County), Pompton Lake (Passaic County), Spruce Run Reservoir (Hunterdon County), Pompton River, Budd Lake, Farrington Lake (Middlesex County), Millstone River and the Passaic River.


The Hackettstown Hatchery crew set one large and one small trapnet in Swartswood Lake on March 24. Water temperatures ranged from 42° to 47°F during the netting period. The nets were checked daily March 25-29. Daily checking was necessary due to the large number of fish per net and the condition of the females (full of eggs).

Walleye females exhibit a tendency to release their eggs in the trapnets if not removed promptly. The walleye spawning run was in full swing and produced an amazing 320 fish over a five-day period. This compared to 303 and 183 walleye captured in 11-day netting sessions in 2002 and 2003, respectively.

Of the 320 walleye captured, 101 were females and the hatchery crew spawned 71 of them producing 6.4 million eggs. The spawned females averaged 90,215 eggs per fish compared to 70,000 eggs each in 2003. The considerably higher eggs per female this year can be attributed to two things.

Stripping walleye eggs
Stripping walleyes and fertilizing eggs in basin
First, this year’s females averaged more than a half-pound and a full inch larger than last year’s fish: 4.3 pounds and 21.2 inches in 2004 versus 3.7 pounds and 20.2 inches in 2003. Second, the Swartswood Lake trapnets produced the two largest walleyes ever captured in Division nets.
Craig Lemon with trophy walleye
Craig Lemon with trophy walleye

On April 28, hatchery staff netted a 12.3 pound, 29-inch gravid female (full of eggs) and the following day netted a 13.6 pound, 29.8-inch gravid female from the same net. The latter fish equaled the current New Jersey State record of 13 pounds 9 ounces taken from the Delaware River in 1993! All of the broodstock were released safely back into Swartswood Lake shortly after egg collection.

Walleyes were also captured from Greenwood Lake (Passaic County) March 30-April 21. These nets were originally set to target muskellunge broodstock. Growth data (length, weight, age) was collected at the hatchery from 27 of the 123 adult walleye that were captured. The Greenwood Lake females averaged 5.5 pounds and 22.8 inches, while the males averaged 2.3 pounds and 18.6 inches.

Walleye eggs take 13 days to hatch with a hatching rate of 40 to 70 percent. The first million fry to hatch are placed in hatchery ponds and are grown to a size of two inches on a diet of plankton. In 2003, a total of 376,000 of these 2-inch walleye fingerlings were stocked into Greenwood Lake, Monksville Reservoir (Passaic County), Lake Hopatcong (Morris County) and the Delaware River. The hatchery set up another 75,000 of these 2-inch pond fingerlings and continued growing them on a fathead minnow diet. About one third or 28,000 of these two-inch fish reached the target size of four-inches and were float stocked in Canistear Reservoir (Sussex County), Lake Hopatcong, Swartswood Lake and Greenwood Lake.

Trapnets were set in Mercer Lake March 29-April 2. This undertaking accomplished two important objectives. The first was to provide the hatchery with 290,000 muskellunge eggs. Incidentally, these eggs were taken about two weeks earlier than the muskie eggs collected from the state’s northern waters. This technique allows hatchery staff to raise these fish right along with the pike and the pike/muskellunge hybrid known as tiger muskies.

Since all three species are tiny yet, water quality in the tank stays high since less food is needed. This is important because more feed means increased ammonia levels in the tank, which can be harmful to the growing fish. The second objective was to provide regional biologists with valuable growth data to help them evaluate the condition of the muskellunge population in Mercer Lake.

The Mercer Lake trapnets captured a total of 19 muskellunge and one tiger muskie. Of the 19 muskies, eight were females producing 289,000 eggs. The largest true-strain muskie collected from Mercer was a ripe female weighing 25.4 pounds and measuring 42.3 inches. The one tiger muskie captured weighed 11.1 pounds and measured 37 inches (the tiger muskie is a cross between a muskellunge and a northern pike). Tigers were stocked in Mercer Lake from 1989 to 1997. Back at the hatchery, one of the Mercer Lake female muskies was spawned with several male northern pike from Budd Lake and the combination produced 36,000 tiger muskie eggs.

Pike and musky
Northern pike (top) and muskellunge used to produce tiger muskie hybirds

Trapnets targeting muskellunge were also placed in Greenwood Lake March 30-April 21. Disappointingly, three large nets produced only 10 muskies over the three-week period. Water temperatures remained very cold, hovering between 38° and 44°F for most of the netting period. Those cold water temperatures are believed to be the cause of the low catch rates. However, water temperatures warmed into the 50s toward the end of the netting period and catch rates improved. The largest fish captured was an egg-laden female weighing 20.7 pounds and measuring 44.8 inches.

Large muskellunge
Allison Byrd with large muskellunge

Finally, trapnets were set in Echo Lake Reservoir April 13-19. Just the opposite of Greenwood Lake, the Echo nets produced 26 muskies in just under a week. Water temperatures ranged from 45° to 54°F; perfect for spawning muskellunge. Of the 26 muskies captured, 16 were females and 10 of these females arrived at the hatchery full of eggs.

These Echo Lake females (of the "Leech Lake” strain) contributed a large portion of the 1.2 million muskie eggs taken by hatchery staff in April. This strain originated from Leech Lake in Minnesota and was brought into New Jersey when Muskies, Inc. Chapter 22 purchased fingerlings in 1991 for stocking in Echo Lake.

Amazingly, one net caught 10 muskies in a 24-hour period on the boat ramp end of the lake. One of the ten turned out to be the first 50 inch muskie the hatchery has ever captured there. It measured 50.4 inches and weighed 31.5 pounds and was a “Leech Lake” strain muskellunge.

This year's muskie eggs hatched at a rate of 59%, producing about 500,000 fry. These fry will be split between indoor and outdoor growing techniques. Half will be earmarked for intensive indoor tank culture, while the others will be placed outside for extensive pond culture.

In 2003, the hatchery raised 8,550 muskie fingerlings ranging between seven and 12 inches for stocking in the following waters: Echo Lake Reservoir, Lake Hopatcong, Mercer Lake, Mountain Lake (Warren County), Greenwood Lake, Carnegie Lake (Middlesex County), Manasquan Reservoir (Monmouth County), Deal Lake (Monmouth County) and the Delaware River.


The 2004 trapnetting season lasted a month and a half. It was a very successful six weeks with some tremendous trophy-sized fish captured, spawned and safely returned to our lakes and reservoirs.

As a hatchery supervisor who started 17 years ago as a seasonal worker, it is unbelievably rewarding to witness the programs created through the dedication and devotion of fisheries staff in the New Jersey Division of Fish and Wildlife. The stocking efforts of some very active fishing clubs have also helped pave the way for some of these great success stories. The crew at the Hackettstown Hatchery did a tremendous job dealing with the harshness of Mother Nature this spring since the nets had to be checked daily, regardless of snow, rain, sleet or high winds.

Currently, all the eggs have hatched and the fish are in excellent condition. The hatchery has stocked some excess fingerlings in the Passaic River (northern pike) and the Delaware River (tiger muskellunge). In addition, the West Virginia Department of Natural Resources made a trip to the Hackettstown facility in April and picked up 14,000 small fingerling (northern pike) as part of a unique inter-state fish exchange program. Meanwhile, the northern pike have grown to 4 inches, tiger muskies to 2 inches and the muskies are now about 1-inch long. The one million walleye fry put into three hatchery ponds are just under one-inch in length. About one million walleye fry were also split between Lake Hopatcong and Greenwood Lake.

Youngster with nice pike
What it's all about - pike caught at Spruce Run.
Photo by Tom Pagliaroli

Keep your eyes out for any tagged muskellunge in Mercer Lake and Echo Lake. The hatchery has tagged about 50 adult muskies with numbered, orange streamer tags. Each tag has an individual number plus the phone number for the Hackettstown Hatchery. We are hoping to get some valuable information about our muskellunge population and its health from the information reported by the angling public. These tagged fish have been back in the water for only a few weeks and the hatchery has had three reports already from successful anglers. Many anglers practice catch and release on these muskellunge making it possible for data to be received for many years to come. Stay tuned to the Hackettstown Hatchery-related pages of the Division’s website for further updates on the progress of this year’s fingerlings, and best wishes for future fishing success!



































































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Last Updated: August 18, 2004