This project will begin to characterize the habitat use and movements of fingerlings and mature brook trout in Beaver Brook Creek, Shu Swamp Preserve in Mill Neck, NY, through a project involving hands-on participation of high school students and the local community. Assessment of the behavior and movements of fingerlings and mature trout through the use of radio-telemetry will be correlated with a stream survey so that habitat restoration efforts can be focused and more likely to lead to a habitat conducive to a breeding and sustainable population of brook trout. In addition, by monitoring for movement of RFID (radio frequency identification)-tagged mature trout between Beaver Brook in Shu Swamp and the brackish Mill Creek we can begin to assess how open the river system is to the coast and what restoration efforts may be needed to improve migration.
Brook trout are a historically important anadromous trout native to eastern North America including Long Island. The population suffered precipitous decline throughout its range in the 19th and 20th centuries due to habitat destruction. Brook trout may now inhabit only 5% of its former historic habitats.
The Long Island Sound Study’s Stewardship Initiative has highlighted the Oyster Bay (Mill Neck) area as a Stewardship Area and a New York State Significant Coastal Wildlife Fish and Wildlife Habitat. The Charles T. Church Nature Sanctuary (Shu Swamp Preserve) has been specifically identified by the Study as a potential freshwater wetlands habitat restoration site. Beaver Brook runs through Shu Swamp and empties into Beaver Lake. Beaver Lake, which is dammed, empties into the tidal and brackish water of Mill Creek. Mill Creek is a tributary of Oyster Bay.
At one time Beaver Brook, like many North Shore spring-fed streams, was host to native brook trout. However data from the New York State Department of Environmental Conservation (NYSDEC) statewide fisheries database indicates that during the period surveyed brook trout were not present in Beaver Brook until 2001 (There is considerable variation in the sampling date due to availability of NYSDEC personnel as well the preference the NYSDEC gave in a given year to which and how many of the streams they could survey at any particular time):
NYSDEC Survey of Beaver Brook Trout Species (from NYSDEC Statewide Fisheries Database)
In the 1990’s the stream was being stocked with brown trout, which are notorious for outcompeting and excluding brook trout from their habitats. From 2000 to 2002 Trout Unlimited (TU) and NYSDEC cooperated in removing brown trout from Beaver Brook. Following the reduction in brown trout numbers, the Cold Spring Harbor Fish Hatchery began a program of intermittent stocking of the stream with brook trout, and NYSDEC surveys began to record an increase in brook trout numbers. The restocking was then continued on a more regular basis through the TU’s Trout-in-the-Classroom (TITC) program beginning in 2003. In February 2008 and March 2009, sampling revealed for the first time, young-of-year, which could only have been the offspring of established trout because stocking that year had yet to take place. Therefore Beaver Brook could now be described as having a spawning population of brook trout. The apparent decline in brook trout numbers in the last sample may have been due to the sampling date being too early.
At present there have been no significant restoration efforts. There has not even been a full systematic evaluation of stream conditions. There is one physical obstacle to movement of fish into Oyster Bay: the Beaver Lake dam with spillway under Cleft Road into Mill Creek. The dam has a rudimentary steel fish ladder that is scheduled to be replaced with a rock passageway in order to allow alewife migration. It is likely that the dam acts as barrier to movement of fish including brook trout. In the mid-2000’s, the runoff from a Japanese garden constructed by the local community caused severe silting with light-colored sand in some of the reaches of the stream. It is believed that this has caused a decline in habitat quality for brook trout because it may have created more favorable conditions for predation by birds.
There is some controversy about whether the Long Island Sound and surrounding watershed hosts brook trout that are “sea run” (i.e., anadromous). Brook trout are not truly anadromous in the same sense as alewife or salmon. Instead some of the freshwater population at an early age will leave freshwater and enter coastal saltwater environments for brief periods of time. “Coasters” or “Salters”, as they are often known, are easy to spot when they return to freshwater because of their distinct coloration. It is clear from the historical record that coastal brook trout used to be reported in the Sound. More recently there have been several reports indicating that they continue to use coastal waters. For example, brook trout showing coastal coloration have been observed near the mouth of Nissequogue Creek and Beekman Creek (the mouth of Beekman is only about 1 mile east of Shu Swamp and like Beaver Creek feeds into Oyster Bay) both of which empty into the Sound. Brook trout attempting to enter from Mill Creek from Beaver Brook would have to pass through Beaver Lake and then over the dam. If they attempted to return they would have the even more difficult task of swimming over the dam except during above average high tides when the Mill Creek water level approaches or overtops the dam.
Currently, the fingerlings and mature fish used in this study are hatchery-reared (from Cold Spring Harbor Fish Hatchery (CSHFH)); more precisely, we are monitoring the movements of hatchery-reared fish released into the wild. Therefore inferences about trout “native” to Beaver Brook based on this data must be made cautiously. Each year, hundreds of fingerling brook trout are released in Beaver Brook by students participating in the Trout-in-the Classroom Program and by CSHFH. Therefore, the data we collect will be particularly informative about how hatchery-reared fingerlings respond upon release. Because RFID tags have unlimited lifespans we will collect data on mature fish for a much longer time. Based on the data we collected on the fish we released this summer and fall it appears that these fish are actively moving for the three to four weeks following release and probably represents an acclimation period. Data on tagged fish detected after this four week period carry more significance in representing the possible behavior of naturalized fish. Future studies might be able to focus specifically on behavior of naturalized fingerlings and brook trout, perhaps through tag and recapture. The present protocol avoids tagging naturalized fish because of the sensitivity of the population in Beaver Brook.
The specific goals are:
- Determine how fingerlings in tributaries of Beaver Brook are affected by stream bottom; more specifically how has the silting event described in Project Needs affected habitat use?
- Determine whether fingerlings seek out cold water seeps and where the seeps are located in Beaver Brook.
- Determine how fingerlings and mature trout respond to surges in water temperature following precipitation events.
- Describe the range of movements of fingerlings and mature trout within the Preserve: do they tend to remain in one particular location or do they range more freely through the various tributaries?
- Through established survey techniques adapted for local community participation (Stream Visual Assessment Protocol (SVAP)), evaluate stream health and correlate fish movements and locations with survey findings.
- In an effort to observe if Beaver Brook brook trout can become sea run, monitor the movements of mature trout between Shu Swamp, Beaver Lake, and Mill Creek.
- Our data on fingerlings and mature trout will be provided to managers and affiliated community groups to allow them to adapt restoration efforts best suited to protect and enhance nursery areas of Long Island Sound tributaries.
- Our data on mature trout will indicate the degree of importance of opening up tributaries (e.g., provide fish ladders) to migration of brook trout, allowing fish to enter coastal waters and to return to breed.