Update on Fish Passage, Fish, and Mussels in the Merrimack River Watershed.
The Essex Dam Fishlift, Lawrence, MA opened for the season on April 17 and the first herring were counted on April 18th. The first American shad arrived on May 5, and two salmon were captured shortly thereafter. Approximately 100 shad and 1,257 herring have been counted at the fishlift. On May 13 the Merrimack River was on the rise and exceeded flood stage with flows at Essex Dam approaching 100,000 cubic feet per second (cfs). This flood was the forth largest event recorded for the period of record (83 years) on the Merrimack River. Persistent high water has precluded the safe removal of debris that filled the fishway during the flood. It has not operated since the flood began on May 13.
The fish lift was reopened yesterday, June 22, 2006 at 10:30 AM. By 3:00 PM five (5) Atlantic salmon were captured and brought to the Nashua National Fish Hatchery. As of 3:30 PM today, June 23, 2006, thirteen (13) additional salmon were captured and transported to the hatchery. The total number of salmon captured to date via electrofishing and use of the fishlift/trap is now 53. Shad and herring numbers have not changed. The river herring run has ceased, and observations suggest that herring did spawn in and along submerged aquatic vegetation downstream from the dam however, spawning habitat is limited in this area.
Because the fish lift and trap have been inoperable, we responded by mobilizing a field crew that has been capturing American shad, Atlantic salmon and river herring in the area immediately downstream of the Essex Dam. As many of you may be aware the Nashua National Fish Hatchery and the North Attleboro National Fish Hatchery have developed and implemented the capability to culture American shad. While the Nashua hatchery is now able to hold and spawn American shad adults, produce eggs, and hatch and mark fry, the North Attleboro hatchery was setup to accept eggs, and hatch and mark fry. Holding tanks have been temporarily installed adjacent to the Essex Dam fishlift to spawn shad on site, and eggs can be transferred to either hatchery. However, without shad in the fishlift/trap our efforts were stymied until the field crew began work with the electrofishing boat on very high water beginning June 5.
Now the encouraging news!!! We were able to capture shad, salmon, and herring electrofishing in early June. Shad and herring samples have been sent for lab/fish health workup, an essential requirement to move juvenile fish out of the hatchery and back in to the river. We continue to capture shad daily and we are successfully spawning shad at the Nashua NFH. The first hatch has produced approximately 300,000 shad fry and about one (1) million eggs are now in hatching jars with adults continuing to produce eggs. We will continue to use the boat (and hopefully the lift in the near future) to capture fish, and we plan on populating the shad spawning tanks at the dam and at the hatchery for the next three weeks. Its intended that eggs will be sent to North Attleboro NFH and adults and eggs transported to Nashua NFH.
Another extraordinary event occurred in the Merrimack River watershed during the flood when the Suncook River eroded its bank and forged a new channel bypassing the original river channel for more than a mile. Its new course also bypassed two dams!! Brook floater mussels a NH State endangered mussel and a FWS species of concern were dewatered in the river bypass reach. With low water and rising river water temperatures state and federal biologists and environmental personnel along with volunteers were able to collect approximately 1,150 mussels on May 17 and brought them to the Nashua NFH. They are doing fine at the hatchery; all have been tagged, and they will be reintroduced in suitable habitat in the Suncook River in the next few weeks. Without the recently installed capability to heat water for shad culture at the Nashua NFH we would not have been able to respond to the mussel crisis. Water at the hatchery can now be heated to a similar temperature as that of the Suncook River to avoid shock and stress. Hatchery staff, staff from FWS New England Field Office, Concord, NH, NH State personnel, and volunteers have done a remarkable job with the mussels!!
Merrimack River water temperature is on the rise (75o F) and the shad migration is typically over by early to mid July. With greater than normal spill over the Essex Dam the fish lift will likely remain inefficient for shad. However, salmon are more adept at locating attraction flow/water at the entrance to the fishway so I will provide updates next week. Additional information about Merrimack River fish passage and river flows can be obtained at: http://www.fws.gov/r5cneafp.
