C Pond Smallmouth Bass Investigations

Fishery Interim Summary Report No. 06-06

By David P. Boucher

Maine Department of Inland Fisheries and Wildlife
Fisheries and Hatcheries Division
Augusta, Maine

December 2006

Interim Summary Report No. 1 (2006)

SUMMARY

C Pond has a surface area of 173 acres and is located in C Surplus Township in north central Oxford County, Maine. C Pond’s outlet forms the Dead Cambridge River, which flows 7.8 miles to Umbagog Lake, the lowermost water body of the Rangeley Chain of Lakes. C Pond remains homothermous during the summer months, but brook trout nonetheless thrive and provide an excellent early-season sport fishery.

Local anglers first reported the presence of smallmouth bass in C Pond in 2001. That same year, Department biologists conducted fish surveys but did not confirm the presence of bass. Additional reports of bass were received in 2002 and 2005.  Trapnet and scuba surveys conducted in 2005 confirmed the presence of small numbers of adult and juvenile bass. Bass most likely migrated upstream from Umbagog Lake where they were illegally introduced during the mid-1980s. The presence of smallmouth bass could severely impact C Pond’s wild brook trout population.

The 2005 surveys suggested that smallmouth bass had not become well established in C Pond, probably because numbers of adult spawners remained low, juvenile habitat was limiting, and large populations of bullheads and cyprinids suppressed the recruitment of young bass. Therefore, we recommended the construction of a fish barrier on the Dead Cambridge River, at the site of the old driving dam, combined with an intensive, long-term effort to physically remove the few bass that had become established in C Pond and its outlet.

In 2006, we made considerable progress in securing private funds, planning the barrier project, and our removal experiments provided important information to guide future work. An electrofishing raft was very effective at capturing all sizes of bass, depending on the season, and we appeared to markedly reduce the 2005 year class by sampling in both June and September. However, our September samples showed that the 2006 cohort was fairly abundant, so some adult bass obviously spawned successfully despite the intensive removal work in June.

This project is providing data on the feasibility of complete bass removal in a relatively large water system that bass have only recently colonized, and where bass nursery habitat is limited. These data, regardless of the ultimate outcome, can be used to assess the efficiency of the technique in managing illegal bass introductions in similar Maine waters. We recommend that the electrofishing project continue for at least two more seasons. If we determine that bass cannot be completely eliminated using the technique, we will consider a chemical reclamation. Successfully treating a 173-acre pond and about 2.8 miles of outlet stream is questionable, but we will seek expert opinions and conduct a thorough review of its feasibility. Regardless of the outcome of either technique, we recommend that the barrier project proceed in 2007. A barrier would remain beneficial because it would exclude other invasive fish species that may become established in Umbagog Lake in the future. For example, rock bass have recently colonized the Androscoggin River below Umbagog Lake, and anglers have reported northern pike from Umbagog Lake, though this remains unconfirmed.

For more information, please contact:

Dave Boucher, Assistant Regional Fishery Biologist
689 Farmington Road
Strong, Maine 04983-9419
Telephone: (207) 778-3322 Ext. 23
Email: dave.boucher@maine.gov