Perch Perca fluviatilis ; Linnaeus, 1758. Family: Percidae
Perch (Perca fluviatilis) are deep-bodied freshwater fish, easily identified by a pair of bristling dorsal fins, a cavernous expandable mouth and a row of five to nine dark stripes running down either side of their bodies. Other defining characters include rough skin, bright red or orange caudal, anal and pectoral fins and a dark spot on the rear of the first dorsal fin. Sharp spines in the first dorsal fin, anal fin and mounted on the gill cover provide protection against predators, so take care when handling. Perch vary in colour depending on their age and where they live, but most are bright green to olive with yellow to yellow green sides and grey to white bellies.
Habitat and Distribution
Perch inhabit lochs and slow-moving rivers from sea level to 1,000 metres. In the summer they are often found near weeds, lilies or other good ambush points. In the winter they become less active and move to deeper water. Perch are widely distributed throughout much of Eurasia, but are non-native to Scotland. Nonetheless, they have been introduced to many Scottish lochs and slower rivers where they have rapidly multiplied, in some cases becoming pests.
Perch spawn in shallow water from April to June, depending on the water conditions. A female escorted by several males circles above submerged branches, tree-roots, weeds or even gravel before extruding up to 200,000 eggs in a single long sticky strand, which one or more of the males quickly fertilises. The eggs hatch after two to three weeks. As a general rule, male perch become sexually mature after two to three years, and female perch after three to four.
Diet and Feeding Behaviour
Perch are opportunistic predators that will try and swallow anything that swims, including their own kin. After hatching, perch larvae feed on rotifers and other microscopic zooplankton before switching to bottom-dwelling insect larvae, pond snails, leeches and other invertebrates. The perch diet also includes small fish such as minnows, roach and other perch. In many waters a few perch grow exceptionally big by cannibalising the others.
Perch have a number of strategies for catching small fish. Smaller perch often swim in shoals that surround and herd their prey. The larger individuals hunt alone. These solitary perch slowly creep up on unsuspecting fish or lie in wait ready to pounce. Perch lack the acceleration of that classic ambush predator, the pike. However, what they lack in speed they make up for in stamina and manoeuvrability. Although diurnal, perch tend to feed most during periods of low light, such as sunrise and sunset, when their superior vision gives them an advantage over their prey.
Perch and People
Perch flesh makes exceptionally good eating. Adjectives that have been used to describe their flesh include white, firm, flaky, and most importantly, boneless and well-flavoured. On the continent perch are farmed and eaten in large numbers. Indeed, in Finland perch is the third most important fish by weight, after herring and sprats.
Perch also make good sport. On a summer's evening the smaller perch can be seen queuing up to take the bait - perfect angling for beginners - while the larger, solitary individuals are sufficiently secretive and wary to make a specimen hunters life interesting. Although no where near the size of a decent pike or salmon, a large perch is a stunning animal. The Scottish rod record stands at 4lb 14oz (2.21 kg), but bigger perch undoubtedly swim in Scottish waters.