- Division of Fisheries and Wildlife
Each fall, MassWildlife samples the Quabbin and Wachusett Reservoirs to monitor lake trout populations. With the help of DCR, MassWildlife surveys lake trout to examine population characteristics. The 2019 fall sampling is complete and crews on Wachusett Reservoir captured and released 142 lake trout including a 37 inch, 18 pound fish. Crews at Quabbin Reservoir captured and released 130 lake trout, 34 at Goodnough Dike and 96 at Windsor Dam. The largest lake trout encountered was originally tagged in 2015 and then recaptured in 2017. That fish, pictured above, measured 33.5 inches and 13.3 pounds. In addition to lake trout, several large landlocked salmon were captured at Quabbin weighing between 6 and 7 pounds.
To capture lake trout, field crews set nets on spawning areas starting at sunset and check them about every 20 minutes. Captured fish are removed from the nets and placed in a livewell. Next, biologists record length, weight, and sex and implant a small Passive Integrated Tag (PIT) in the fish. Prior to release, the adipose fin is clipped to provide an external mark indicating that the fish has been captured before. Data collected provide biologists with an understanding of the current condition of lake trout populations. If fish are recaptured from previous tagging efforts, biologists can calculate individual growth rates. Lake trout are long lived and slow growing and it is not uncommon for a tagged fish to be recaptured 10 years later. In fact, the longest recapture interval recorded was 24 years! When other species like landlocked salmon, smallmouth bass, rock bass, and white perch are captured, biologists record information including length, weight, and sex but do not implant PIT tags.
Lake trout typically spawn in late October and November when the surface water temperatures are around or below 50°F. The spawning grounds are typically shallow, rocky waters on windy shores of the Reservoirs; spawning occurs mostly after dusk. Night sampling on big waters can be cold and icy in November, but the information it provides biologists is well worth the effort. Sampling efforts like this are just one way that MassWildlife monitors the health of the fish resources of the Commonwealth.