Juvenile Sampling

Passive Trapping Methods

 In August 2007, we installed passive trapping devices at the Ipswich Mills Dam and below the USGS weir (below Willowdale Dam). These traps are designed to capture the downstream migrating juvenile river herring, and are located at areas that act as bottlenecks during low flow.

At the Ipswich Mills Dam, we have installed a modified drop net. It is placed into the fishway and collects juvenile fish utilizing the fishway to move downstream. If there is spill over the dam, juveniles may swim over the dam instead. We are grateful for our volunteer assistants installing the trap each morning.

Below Willowdale Dam, we installed a modified inclined plane trap. The flow over the USGS gaging weir is concentrated toward the body of the trap, and the wings on either side help direct fish into the trap for collection. When water is not spilling over the dam during low flow, the fishway at Willowdale provides the only route for juvenile fish to migrate downstream.

Each afternoon both traps are checked, and captured fish are identified, measured, and released. The juvenile traps were built by Ed Clark and Luis Carmo of the MA Divison of Marine Fisheries, and were utilized in 2005 juvenile sampling efforts in the Ipswich River. Marine Fisheries technicians and UMass students clear the fishways and check the traps each day. 

Electrofishing

In August 2007, we initiated an electrofishing sampling procedure, directed by Joe Smith (MACFWRU, UMass Amherst). Each week we sample several sites using a backpack electrofisher, which is on loan from Linda Deegan of the MBL. Captured fish are identified, measured, and released at their capture site. Details regarding habitat, depth, and location are recorded at each site.

*Results listed below represent preliminary data that has not been audited. Passively trapped fish generally belong to the young-of-the-year (yoy)cohort.

Ipswich Mills Trapping Results

8/14/07       1 Pumpkinseed

8/28/07       2 White Chubsucker

                   1 Pumpkinseed

8/30/07       2 White Chubsucker

                   1 Golden Shiner

9/25/07       1 Sunfish

9/28/07       4 Largemouth Bass

                   5 Redbreast Sunfish

                   1 Banded Sunfish

Willowdale Trapping Results

8/16/07       4 Largemouth Bass

                   1 American Eel

8/17/07       1 Golden Shiner

                   8 Largemouth Bass

8/20/07       4 Largemouth Bass

8/21/07       1 Largemouth Bass

8/23/07       1 American Eel

8/30/07       1 Brown Bullhead

8/28/07       2 Brown Bullhead

8/29/07       9 Largemouth Bass

9/7/07         1 Golden Shiner

9/8/07         1 Brown Bullhead

9/10/07       1 American Eel

9/12/07       10 Largemouth Bass

                   4 American Eel

                   1 Chain Pickerel

                   1 Lamprey

9/13/07       3 Largemouth Bass

                   6 American Eel

                   2 Redfin Pickerel

                   1 Golden Shiner

9/14/07       1 Banded Sunfish

                   3 Largemouth Bass

                   8 American Eel

9/17/07       1 Largemouth Bass

9/18/07       19 American Eel

9/19/07       24 American Eels

                   1 Largemouth Bass

9/20/07       29 American Eel

9/21/07       18 American Eel

9/22/07       3 American Eel

9/23/07       5 American Eel

9/24/07       6 Bluegill Sunfish

10/10/07     1 American Eel

10/13/07     7 American Eel

10/15/07     4 American Eel

                   1 Largemouth Bass

                   1 Chain Pickerel

Electrofishing Results

Week 1       3 American Eel

                   1 Pumpkinseed

                   1 Redfin Pickerel

                   1 Chain Pickerel

                   1 Green Sunfish

Week 2       1 Chain Pickerel

                   4 Pumpkinseed

                   2 Redfin Pickerel

                   4 American Eel

                   1 Largemouth Bass (yoy)

Week 3       2 American Eel

                   4 Pumpkinseed

                   1 Redbreast Sunfish

Week 4       3 Redfin Pickerel

                   1 Chain Pickerel

                   1 Swamp Darter

                   2 Bluegill

                   5 Pumpkinseed

                   1 Redbreast Sunfish

                   1 Yellow Perch

                   1 Yellow Bullhead

Week 5       8 Pumpkinseed

                   2 Smallmouth Bass

                   1 Redbreast Sunfish

                   1 Redfin Pickerel

Week 6       2 American Eel

                   1 Yellow Bullhead

                   1 Chain Pickerel

                   1 Pumpkinseed

Week 7       2 Pumpkinseed

                   1 Redbreast Sunfish

Week 8       7 Pumpkinseed

                   1 American Eel

                   2 Largemouth bass

                   1 Redbreast Sunfish

                   1 Bluegill