Although winter is still upon us, a sign of the coming spring is making its presence known. Fishermen know and eagerly await these last weeks of winter. Yellow perch (Perca flavescens) make their spawning run from late February to mid-March and offer some of the earliest opportunities for sport fishermen to break out their rods and tackle.
A strikingly handsome fish, yellow perch are recognized by golden yellow bodies marked by several vertical bands and red or gold lower fins.
Yellow perch are semi-anadromous, spending most of the year in brackish water and migrating to freshwater to spawn. Yellow perch never leave the river system where they hatched, they merely move between brackish and fresh water. The gradual warming of water triggers spawning.
Females deposit an accordion-like chain of eggs in areas with large amounts of organic debris. The egg chain may be fertilized by as many as 15–25 males. Once spawning is completed, adults leave the eggs and migrate back to brackish water.
The egg chain may be attached to underwater vegetation or bottom debris. The unusual shape of the chain allows water to swirl gently around and through the chain, aerating the eggs. This is essential for respiration and to prevent bacteria and fungi from growing on and killing the eggs.
Eggs hatch in two to three weeks. After a few days, the larval fish begin feeding on microscopic organisms.
Later, juvenile fish will join adults in the brackish portion of river. Males reach sexual maturity in one to three years; females in three to four.
Because yellow perch congregate in small stretches of streams when spawning, they are vulnerable to a variety of threats and acid rain to loss of spawning habitat to overfishing.
Overall, the Chesapeake Bay population of yellow perch is relatively stable, with populations most prevalent in the Upper Bay. In the middle and lower Bay, some populations are depressed with smaller or no spawning runs. Historically, these areas had large populations of yellow perch.
No one cause has been identified as the reason for these regional differences. Each life stage of yellow perch is sensitive to different environmental factors.
Agriculture and urban development increases the amount of sediment, nutrients and chemicals entering streams. This same development reduces the amount of naturally vegetated areas surrounding rivers and streams that would absorb these substances.
Excessive sediment adheres to eggs, reducing the oxygen they receive. Sedimentation may reduce hatching success or delay hatching time. The larvae’s survival is also reduced when fine grains adhere to and damage sensitive gills.
Excessive nutrients affect all fish populations by altering the physical characteristics of water—raising water temperature and reducing dissolved oxygen.
Low dissolved oxygen retards growth and, in some cases, can kill fish. Some fish may leave their preferred habitat because of low dissolved oxygen and temperature changes. The resulting changes can also reduce the benthic organisms that yellow perch prey on.
Although adult perch are somewhat acid-tolerant, newly hatched perch are more sensitive to acidic conditions. Sulfur and nitrogen oxides emitted into the air through the burning of fossil fuels mix with water vapor, forming sulfuric and nitric acids that fall back to the ground as acid rain. Chronic exposure to slight to moderate acidic conditions can inhibit fish growth and damage body organs. Young fish may be killed when heavy rains result in a pulse of highly acidic water moving downstream.
Acid rain dissolves and releases aluminum in the soil. Dissolved aluminum also threatens yellow perch. The effects of aluminum include disruption of the fish’s metabolism and respiratory distress. A combination of acidity and aluminum is lethal to juveniles.
Liming has been used to help neutralize acidic water in some streams. Composed of calcium carbonate, limestone can raise the pH of the water. Ultimately, the reduction of acid rain depends on the reduction of sulfur emissions from industry and automotive exhaust.
Another problem that fish, including yellow perch, face is not being able to reach spawning grounds because of blockages. Gauging stations, road culverts and dams block tributaries. Unable to get around blockages, adults will not spawn. A fish passage plan is currently working to remove blockages throughout the Bay watershed.
The yellow perch commercial fishery has become more important since the imposition of the American shad fishing ban. Commercial fishermen use fyke nets to catch yellow perch during their spawning runs.
Recreational fishing for yellow perch has become a tradition for many anglers as the fish are the first to arrive in the rivers after the long winter. Their delicate flavor also makes them a favorite.
Maryland has a partial ban on fishing for yellow perch. The Magothy, Nanticoke, Patapsco, Severn, South and West rivers are closed to recreational and commercial fishing. In addition to these rivers, the commercial yellow perch fishery is also closed in the Choptank, Miles and Wye rivers.
Neither Virginia nor Pennsylvania has closed rivers to fishing for yellow perch. Anglers, though, need to contact their state fishery agency to check the regulations on gear, catch limit and minimum size requirements.
Many anglers are lured to the Chesapeake Bay watershed because of the variety of fish species it supports. The annual spring run of yellow perch is just one of the many natural events that attract commercial and recreational fishermen alike.
High-quality aquatic habitat, clean water and clear passageways to spawning habitat are essential to sustain yellow perch as well as other important fish species such as American shad, alewife, blueback herring, American eel and striped bass.