Yellow Perch Habitat Investigations

Yellow Perch Hatchery

Yellow perch​ stocks in many rivers systems in Maryland's portion of the Chesapeake Bay have declined in recent decades. Rigorous assessment of aquatic habitat health from an ecosystem approach is emerging as a new technique to manage resources. Changes in habitat quality and quantity caused by human impacts are likely to be responsible for at least some declines of aquatic organisms. In particular, impacts that diminish water quality in the watershed can reduce survival during critical life history stages and thus, reduce abundance. Evaluation of survival of egg and larval, juvenile, sub adult and adult fish can be used to determine factors that limit stock abundance.

Stocking marked fish can also be used to collect valuable stock assessment information from the population. Many commonly employed mark-recapture strategies employed in fisheries management lend themselves to this type of assessment. Stocking multiple sizes and ages of fish (larval, juvenile) enables evaluation of survival for these life stages. Survival can be affected by specific habitat and water quality variables. These data can be used to evaluate impediments to recruitment caused by degraded water quality or the environment. Learning how human-induced changes affect recruitment to the population can focus mitigation attention to remedy adverse impacts and improve the habitat.

Past Yellow Perch Restoration Efforts, 2001-2005

Yellow Perch Hatchery

Selection of tributaries that could benefit from restoration is critical. The tributary must have once had suitable habitat to support the various life history stages of the organism. Selection should be based on historic and current data on the status of the population. In the early 2000s, two rivers that met these criteria were the Severn River and South River. These rivers once supported abundant populations of yellow perch. Historical scientific information on the populations exist and surveys were conducted to document the occurrence of perch in these rivers. Development has been heavy in these watersheds, which significantly affects water quality and habitat. Evaluation of the quality and potential productivity in these developed watersheds was valuable to develop an approach to managing aquatic resources and fish populations.

Maryland Department of Natural Resources Fish Health and Hatcheries Program conducted a pilot project for restoration of Severn River and South River yellow perch during the spring of 2001. This included the development of reliable production and marking techniques to produce fish for stocking and to assess the impacts of stocking efforts. Techniques included induced spawning of adult yellow perch using hormonal stimulation, oxytetracycline marking trials to determine optimal doses for effective marking, cultivation of perch of several ages and sizes for stocking, and development of methods to uniquely mark fish stocked at different sizes. In order to enhance and evaluate river ecosystems we initiated a three-year stocking program in 2002. Pre-spawned adults were collected from fyke nets set in targeted tributaries. Adults were transported to the state’s Joseph Manning Hatchery and induced to spawn in tanks. Perch were marked and stocked as larvae and juveniles in the Severn River and South River. Approximately 600,000 larvae and 400,000 juveniles were released into these tributaries.

A monitoring program was conducted in both watersheds to collect yellow perch. Sampling was conducted over the range of occurrence for juveniles immediately following each stocking event. Approximately 450 yellow perch that were captured in the survey were analyzed to determine hatchery or natural origin. Results indicated that the hatchery fish had good survival up to juvenile size. The contribution of wild perch and those stocked as larvae and juveniles was used to determine parameters, such as survival and abundance, using mark-recapture models. These sampling efforts were useful to assess the population status in these rivers and evaluate the watershed ecosystem health.

Results of the investigation indicated that the major impediments to successful yellow perch populations on the Severn and South rivers are poor recruitment and low juvenile indices. This is due the associations of impervious surface and development with yellow perch health and spawning success. Until these issues are addressed, the success of corrective stocking will be limited. 2005 was the last year that the Fish Health and Hatcheries Program stocked yellow perch in the Severn River and South River.

Current Yellow Perch Restoration Efforts, 2015 - present

Due to concerns with declining spawning runs and reduced yellow perch populations in some historically productive fishing locations in Southern Maryland, the department decided to supplement wild populations with hatchery produced fish. Stocking efforts are intended to contribute positive impacts to reduced or declining fish populations. Yellow perch egg chains are acquired from tributaries with healthy populations and transported to the Manning State Hatchery to be cultured and marked prior to stocking. Since 2015, more than 50,000 juvenile yellow perch have been stocked into Allens Fresh, a tributary of the Wicomico River in Charles County. Yellow perch stocking can be used to enhance fish populations and improve angling opportunities. Stocking into Allens Fresh will continue as the department evaluates the impacts of stock enhancement efforts on the local yellow perch population.