TROUT MOVEMENTS ON DELAWARE RIVER SYSTEM TAIL-WATERS IN NEW YORK STATE Scott Douglas Stanton BIOLOGICAL FIELD STATION COOPERSTOWN, NEW YORK Occasional Paper No. 34 September 2000 STATE UNIVERSITY COLLEGE AT ONEONTA ABSTRACT In order to detennine the cause of trout movements throughout the Delaware and Beaverkill river systems, a radiotelemetry study, funded by Trout Unlimited (TU) in cooperation with the New York State Department of Environmental Conservation (DEC), was undertaken. In the 1995 year long pilot study, a group of 55 trout, composed of both rainbow and brown trout, were tagged. The fish tagged were found throughout the Beaverkill River, the East Branch of the Delaware River below the Pepacton Reservoir, the West Branch ofthe Delaware River below the Cannonsville Reservoir, and the main stem of the Delaware River below Hancock, New York. In 1996, 56 trout were similarly tagged throughout the same system. In 1997, only one more fish was tagged. The overall goals of this study were to track migration related to seasonal spawning and to detennine the extent of use of tributaries for this spawning. Seasonal movements were also tracked during the wanner months of the year, when certain waters become too wann and potentially force trout to seek cooler thennal refuges present in the river system. The sections of the East and West Branches of the Delaware River, which lie below the New York City Watershed Reservoirs, are tailwater fisheries. Trout there are dependent on cold water releases from these reservoirs throughout the entire year. The West branch receives strong cold water releases of350-600 cubic feet per second (cfs) periodically throughout the year, compared to the East branch of the Delaware which only receives 90 cfs (McBride, 1997). Throughout the summer and fall of 1995, trout movement took place throughout the entire watershed, as the fish seemed to seek cooler refuges in relation to the wann water temperatures. Trout tagged in the West Branch of the Delaware remained there throughout the summer, as the cool water releases from the Cannonsville Reservoir kept the water temperatures suitable for their survival. Both brown trout (Sa/mo trutta) and rainbow trout (Oncorhynchus mykiss) showed movement throughout the entire system in the spring and the fall of 1995, and utilized various tributaries for spawning. In 1996, tagging was changed with respect to the number of tags placed in each river. With the West branch fish known to remain stationary throughout the year, fewer tags were used in this area in the continuation in 1996. A greater number of tags were put out in the lower East Branch of the Delaware, the main stem of the Delaware, and the Beaverkill River in an effort to study the movements of the trout as the waters there became wann in the summer months. The summer of 1996 showed very different water temperatures than those found in the previous summer. Water levels remained high throughout the season, and trout remained stationary with only slight movements due to sudden discharge releases. Certain fish did show movements in relation to highly turbid water associated with steady heavy rain, and the overflow ofboth reservoir systems. Fall 1996 temperatures cooled the waters again. Water levels in both systems were very low during the months of September and October due to drawdown releases of both the Pepacton and Cannonsville Reservoirs. Discharges as of mid October were at about 35 cfs out of Cannonsville, and steady 90 cfs out of the Pepacton Reservoir (McBride, 1997). 11 Brown trout began to move during the fall spawning run with fish from the East branch, Beaverkill, and Delaware River all utilizing various tributaries throughout the watershed. Brown trout within the West Branch had moved up the river and into areas of gravel, which provides ideal spawning habitats. In 1997, the third year of the study, only one more new fish was tagged. This was a two­ year-old female brown trout. This fish was hatchery raised, and tagged purposely in order to determine the migratory action of a fish raised in a hatchery environment. As expected, this fish remained stationary. .. 111 CONTENTS ABSTRACT .i INTRODUCTION 1 SAMPLE AREA 2 Description 3 Discharge 4 METHODS 5 Tagging ofFish 7 RESULTS 12 Migration ofTrollt. 12 West Branch of the Delaware River 16 Movement Related to Water Temperature 16 Movement Related to Spawning 17 Main Stem ofthe Delaware River. 19 Movement Related to Water Temperature 19 Movement Related to Spawning 22 East Branch of the Delaware River.. 24 Movement Related to Water Temperature 24 Movement Related to Spawning 27 Beaverkill River 29 Movement Related to Water Temperature 29 Movement Related to Spawning 30 CONCLUSIONS 31 Thermal Refuges 33 Spawning Streams 34 LITERATURE CITED 36 APPENDICES 39 INTRODUCTION Following a feasibility study from mid April to the end of May 1994, conducted by NYSDEC, a pilot study was initiated in 1995 on the Delaware River tailwaters and the Beaverkill River. This study was to determine the causes and timing of trout movements within this system, encompassing these two rivers. Funded by the New York State Department of Environmental Conservation (DEC) and Trout Unlimited (TU), the study was continued in 1996 and 1997. The goal was to gain insight into different aspects of the migration of the trout species involved. Migration related to seasonal spawning, and the extent ofthe use oftributaries for spawning was determined, as well as the identification of critical habitats. Rainbow and brown trout, both hatchery raised and wild, were used in the study. The extent to which migration is affected by factors such as water temperature and the urge to spawn was considered. Both funding organizations, the NYSDEC and TU, were interested in supporting the study in hopes that a better understanding could be reached regarding the trout resource in order to manage it more productively and to protect it as a wild fishery. These organizations also strive to keep the waters bountiful for the many anglers who utilize the watershed for sport fishing and enjoyment. The Delaware River tailwaters are located below New York City Watershed Reservoirs, and are managed and regulated as a world class trout fishery. The goal of this particular study was to locate prime spawning areas and determine seasonal movements and locations of trout in the system in relation to water temperature and spawning. By determining the spawning movements related to fish migration, as well as locating prime spawning areas, the rivers can be better managed as trout fisheries. By discovering what does, or can, affect the migration of rainbow and brown trout, we are better able to design regulations to be put into effect in areas to improve propagation. These regulations should be in areas where they can best protect these fish, their spawning locations, nursery areas in tributaries, and also cool water refuge areas during the low summer flows. Locating prime spawning areas within the river system will allow management practices to be tailored to protect these areas. It will also document prime spawning locations and allow yearly recruitment of the young of the tracked rainbow and browns, which can then become the brood stock for the Delaware River system. By locating these areas, regulations can be created to protect the tracked fish so that the survival of young trout is insured, or increased. Secondly, due to the trouts' movement into specific locations, areas of cool water refuge can be determined. These are the usual places to which trout can relocate in order to survive the hot, dry summer months. It is during this time that the river is under low discharge conditions requiring releases from the reservoirs. By locating these refugia, releases can be timed to provide considerable benefits to the trout. The Delaware River watershed consists of both the West and East branches of the Delaware River, the main Delaware River, and the Beaverkill River. This watershed is managed as a trout fishery. Anglers from across the country fish the Delaware River system because of the number offish, as well as the quality of the sport of fishing. The West branch and the main stem of the Delaware River are managed for wild fisheries, without any stocking taking place. The East branch and the Beaverkill River are both stocked fisheries. 2 SAMPLE AREA The sample area included the watershed encompassing parts of the Delaware and Beaverkill rivers. This complex system covers an area of243.1 km (l51 river miles) and displays virtually every characteristic that can be found in such a system. By encompassing the entire watershed, data gathered would be more reliable and cover a broader spectrum of characteristics and factors. See Figure 3. N I l I w E 8l 0 S 10 IS L .... I , ! "'\,Iets Figure 3. Salnple Area Used in Study 3 The East Branch of the Delaware can most easily be thought ofas two river parts, the upper and lower East branches with the Beaver Kill confluence acting as the dividing line. The upper East branch flows from the Pepacton Reservoir dam for 27.36km (17 miles) before meeting with the Beaver Kill. The Beaver Kill runs 24.l5km (15 miles) from its point of junction with the Willowemoc Creek. The lower East Branch flows for 24.l5km (15 miles) from the town ofEast Branch, NY, where the Beaver Kill meets it, to the town of Hancock, NY. The West branch ofthe Delaware originates at the Cannonsville Reservoir and runs for 89.76km (17 miles) before merging with the East branch. At that point it is known only as the main stem ofthe Delaware River. The upper l6.42km (10.2 miles) are located in the state of New York while the lower l2.07km (7.5 miles) of river form the boundary between the states ofNew York and Pennsylvania (McBride, 1997).