Our research is through the USGS Massachusetts Cooperative Fish and Wildlife Research Unit, which is a collaboration between the University of Massachusetts, Amherst, Massachusetts Division of Marine Fisheries, USGS, and the Wildlife Management Institute. The MA CFWRU mission is graduate education and to perform research of interest to its cooperators. The Massachusetts Division of Marine Fisheries is the primary partner of the river herring restoration research. The Ipswich River is part of the Plum Island Ecosystem, and we have had the pleasure to collaborate with researchers from the PIE Long Term Ecological Research (LTER) network.
Massachusetts Division of Marine Fisheries
Massachusetts Cooperative Fish and Wildlife Research Unit
University of Massachusetts - Amherst Department of Natural Resources Conservation
Plum Island Ecosystems Long Term Ecological Research
Equipment
We are using NTC-6-1 transmitters, SRX-400 receivers from Lotek Wireless. Two sites along the river have ASP-8 switchboxes from Lotek Wireless, which allow us to determine the upstream and downstream movement of fish at dams. We are using 4-element Yagi antennas from Grant Systems to track the river herring in the Ipswich River.
Release Treatments
In 2006, we tagged river herring that were stocked to the Ipswich River from the Nemasket River. Following the stocking event in 2006, we also tagged river herring captured migrating upstream in the Ipswich Mills Dam box trap. Because the stocked river herring were capable of descending below the Ipswich Mills Dam and moving back upstream, we did not know if we were tagging native upstream migrants or stocked fish that decided to stay in the Ipswich River after initially heading downstream.
This year, we were able to tag upstream migrating alewives in the Ipswich River prior to the stocking event. We have also designed a reciprocal stocking experiment. This means that we are releasing some of the upstream migrating fish at the Ipswich Mills Dam (as was done last year), but we are also transporting some of the trapped fish upstream to the site that Nemasket River fish are stocked. We are hoping that we can learn if the process of transport and stocking, as well as the location in the river itself, affects the behavior of the fish. River herring were transported from the Nemasket River and were stocked at the typical stocking site in Topsfield, or were moved downstream to the trap site at Ipswich Mills Dam. We hope to find out if the location that the fish are stocked affects their behavior.
Manual Tracking
Following the release of the first native upstream migrating fish in 2007, we began an intensive manual tracking process to find the tagged fish in the river. We tracked fish 6 times a week using a Yagi antenna mounted on a kayak, connected to a manual receiver with GPS attachment, which allowed us to record the approximate location of the fish in the water. By adjusting the gain settings on the receiver and the direction of the antenna, we could more precisely locate the tagged fish. We concentrated our efforts on two areas determined to be "hotspots" of high fish activity from our 2006 stationary receiver data. In these two areas, we tracked fish as we kayaked downstream, and also stopped at randomly selected listening posts to listen for tagged fish signals. Outside of these two hotspots, we also used the manual tracking equipment to detect fish at the Ipswich Twon Wharf, which is downstream of our last receiver. Several of the adopted fish we located using our manual tracking efforts, and at least one tag (without a fish) was recovered with this method.
Habitat Assessment
The habitat assessment occurred in stages, using a Geographic Information System (GIS), followed by habitat unit identification and transects in the river. In the GIS phase, we examined the landuse, topology, and width of the river, and used information from the telemetry portion of the study to delineate areas of the river to focus on. Our habitat assessment extends from the Ipswich Town Wharf upstream to the Salem Road Bridge (Topsfield). Using the widths of the river determined from GIS using the measure tool, we estimated an average width and used this to space a series of transects along the river. We also used GIS to set boundaries between reaches of the river (sections with common characteristics, such as flow, gradient, slope). Starting in August, during a low-flow stage of the river, we began to identify habitat units (categorized first as riffles, runs, and pools, then further classified based on other characteristics) and unique features (beaver dams, large wood debris, vegetation patches) in the river. We used a system of identification similar to McCain et al 1990, with slight modifications to account for the slow flow of the Ipswich River. Following this we began an intensive transect survey, in which we measured or estimated the canopy cover, substrate size, in-stream cover, vegetation, and width and depth of the river. We also recorded flow and discharge. We plan to repeat the habitat survey again in the fall and spring, to assess what changes occur in the river seasonally and how this may affect the river herring at their different life stages.
Juvenile Sampling
Starting in August 2007, we have been using both passive and active methods to try and find juvenile river herring produced by the stocked and native upstream migrating fish. The passive methods, two traps built by the MA Division of Marine Fisheries and installed at low-flow "bottlenecks" in the river, were also used in 2005 for presence-absence sampling of river herring (no river herring were collected). We have also electrofished several areas of the river using a back-pack electroshocker on loan from Linda Deegan of the PIE LTER (MBL). Results are located on the Juvenile Sampling page. Passive trapping will proceed until water levels rise and render the trap ineffective, and electroshocking will proceed until mid-November. Several studies describing the downstream passage of juvenile river herring note that increased water flow and dropping temperatures is often associated with, or a cue for, the juvenile out-migration.