Reproductive Health of Yellow Perch, Perca falavescens, in Tributaries

Baltimore Yellow Perch ! P a Upper Yellow perch live in creeks, rivers, ta ps Bay co ponds, lakes and estuaries across the R . . r R te central and eastern United States Severn es h (SE) ^_ C and Canada. In the Chesapeake Bay, S Upper ev South er Choptank n they tolerate salinities up to one third (SO) R ! . Eastern Shore ^_S Annapolis ou MD the strength of seawater. The adults DC th R . reside in brackish waters of the Bay Western Shore Choptank ^_ (CH) DE tributaries and migrate upstream to VA MD spawn. Yellow perch are eagerly sought by recreational fishermen for their

C A) C (M h excellent taste and, because their late h o an p m tan wo e k ^_ tta R winter spawning runs are the earliest a s . M r. C a an of the year, as a harbinger of spring. m p wo a e att Yellow perch also support a small, M a Allen's Fresh P a k . (AF) tu valuable, tightly regulated commercial ^_ W x e R e e i n c t k o R o . B c fishery in ’s portion of m i t i a c n o a y Chesapeake Bay. R N . ^_ Background ² Potomac R. Sample locations th 0 5 10 Watershed boundary In the early 20 century, the Kilometers Chesapeake Bay supported a major Figure 1. Locations and watersheds sampled (2007–2009) commercial yellow perch fishery. This catch declined drastically reaching a counts are not consistently collected for low in the late 1970s. In the early 1980s, all tributaries; however, they are useful Maryland Department of Natural for comparing spawns among rivers. In Resources (DNR) reported a decline spring, DNR conducts larval surveys in recreational fishing for yellow perch in some Bay tributaries and calculates in rivers in the -Washington- the percent of samples with yellow Annapolis area that had long been perch larvae. This index provides an closed to commercial fishing. After indication of how well eggs and early being closed to recreational fishing for larvae have survived. spawning success (South and Severn yellow perch for 20 years, these rivers Rivers) with (a were reopened in 2009. The DNR noted Survey Goals rapidly suburbanizing watershed, but the decline in egg hatching success We studied five Chesapeake Bay still having extensive forest cover), from over 80% during the 1920s to tributaries (Figure 1) with varying (largely agricultural), 1960 to less than 10% in 2001 to 2005 degrees of urbanization indicated by and Allen’s Fresh (largely forested). and concluded that banning fishing impervious surface percentages (the would not overcome the poor hatch. more roads, roofs, parking lots, etc., Field and Laboratory Work It appeared that these western shore the higher the impervious surface During the 2007, 2008, and 2009 yellow perch fisheries were supported percentage): Choptank (2%), Allen’s spawning seasons, we collected about by occasional “natural stocking” from Fresh (5%), Mattawoman (10%), Severn 10 male and 10 female yellow perch strong upper Bay year-classes. (21%), and South (25%). from these rivers (Figure 1). To compare the reproductive status of In the rivers of the Chesapeake, yellow The goal was to compare the the spawning fish, we (1) examined perch usually spawn in early March. reproductive health of yellow perch the ovaries and testes microscopically, Females extrude long, accordion- from historically important spawning (2) made sperm counts, (3) measured like egg chains which are fertilized areas to better understand the sperm motility (movement) and other by males. These chains can be easily reasons for reduced reproduction. We measures of sperm quality, and (4) counted by volunteers walking stream compared two tributaries with highly measured plasma concentrations banks or in kayaks. The egg mass suburbanized watersheds and very low of vitellogenin (a protein involved in the production of egg yolk) and Resources. Funding was provided Total Environment 447:198-209. reproductive hormones. by Mirant Corporation (now a part of NRG Corp.), USFWS, and the Contacts Key Findings USGS’ Chesapeake Bay Priority Dr. Vicki Blazer, In females, we observed two Ecosystems, Fisheries and Toxic [email protected], 304/724 4434 types of egg abnormalities: thin Substances Hydrology programs. We Dr. Fred Pinkney, and irregular zona pellucida (egg appreciate the assistance of the Coastal [email protected], 410/573 4544 envelope) and abnormal yolks (Figure Conservation Association Maryland Dr. Jim Uphoff, 2). The percentage of egg envelope and Arlington Echo. [email protected], 410/226 0078 abnormalities was highest in perch from the South (2007) and Severn For More Information (2008, 2009) Rivers. In all three years, Blazer, V.S., A.E. Pinkney, J.A. Jenkins, the percentage of yolk abnormalities L.R. Iwanowicz, S. Minkkinen, R.O. was significantly higher in the Severn Draugelis-Dale, and J.H. Uphoff. 2013. and South River perch compared with Reproductive health of yellow perch all other locations. In all years, none Perca flavescens in selected tributaries of the females had eggs of the Chesapeake Bay. Science of the that were fully developed at the time of collection.

In males, the major microscopic Figure 2. Microscopic appearance of yellow perch gonads. A. Normal stage 3 abnormality was an increase in the oocyte with yolk globules (a) and zona pellucida or envelope (b). B. Normal stage number and size of Leydig cells, which 4 oocyte with fused yolk (a) and egg envelope (b). C. Abnormal oocytes from a secrete the hormone testosterone. South River perch with thin, irregular egg envelope (arrows). D. Oocytes from This abnormality was observed in a Severn River perch with abnormal yolk (arrows). E. Enlarged Leydig cells perch from the Severn River and less (arrows) in the testis of a Severn River perch. F. Abnormal accumulation of commonly from Mattawoman Creek. Leydig cells (a) in testis of a Severn River perch. There was no consistent ranking in the rivers with respect to sperm counts. Sperm motility was significantly higher in the Choptank perch compared with Mattawoman perch (in 2008) and compared with both Mattawoman and Severn perch (in 2009).

Conclusions and Recommendations We documented abnormalities in yellow perch ovaries and testes at spawning time. The most frequent and severe problems were in perch from the South and Severn Rivers, within the most suburban watersheds. Detecting these abnormalities helps explain the biology behind poor survival of yellow perch eggs and larvae in these rivers. Published studies suggest that the abnormalities may result from exposure to environmental contaminants. Follow-up studies are needed to discover which contaminants may be involved, how such contaminants enter and move through the rivers, and how they affect the fish.

The Research Team Partners included the U.S. Geological Survey’s National Fish Health Research Laboratory, U.S. Fish and Wildlife Service’s Chesapeake Bay Field Office and Maryland Fisheries Resource Office, USGS National Wetland Research Center, and Maryland Department of Natural