Most coarse fish species either lay large numbers of eggs which are left to survive on their own, or they produce relatively small amounts and then guard them fiercely. The zander, however, does a bit of both – it digs a redd, lays about one million eggs and then guards them until they hatch. The fry must then defend themselves among a host of enemies.
Other mature fish which produce massive numbers of eggs include carp (one and a half million), common bream (a quarter of a million) and tench (up to three quarters of a million). The stickleback is probably the only fish which lays very few eggs (90-450) and protects them carefully before and after they hatch.
Pike, carp, tench and bream lay their sticky eggs on weeds. Barbel and zander prefer stones and gravel – while perch string their eggs over sunken tree roots, weeds or reed stems.
All British coarse fish spawn in spring — this is an advantage because food is easily available, and the fry have all summer to feed in the nutrient-rich water. Depending on the weather, pike spawn very early -usually March or April. Perch spawn in April while most members of the carp family (including roach and bream) shed their eggs in May or June.
Spawning is triggered by a combination of day length and temperature. Males in the carp family develop hard white tubercles on their heads and bodies which they use to buffet the females. Large shoals of roach and bream move into shallow water and then engage in frantic buffeting, stimulating the females to release their eggs which the males then fertilize.
Female pike move into shallow water -usually with as many as six or seven males following close behind.
Coarse fish reach sexual maturity at different ages, according to species and sex. Generally, males mature a year earlier than females. Male pike and perch, for instance, mature in about two years; their gonads develop mainly during the winter and spring. Females on the other hand take about three years to mature. Their ovaries are quite small in October. From November onwards, however, they swell, and by March they can make up as much as 15-20% of their weight. Roach, carp, tench and bream undergo similar physical changes. Ovary development in tench, for example, can increase their weight by 20%.
Most fish do not feed during the spawning period, but afterwards they feed intensively – species such as pike eat as much as 60% of their annual intake during the post-spawning period.
For many years there has been a close season in parts of Britain. This usually lasts for three months (generally March 15 -June 15) and is intended to protect coarse fish during the spawning period. Whether fish need a close season is a debatable point. Most anglers return their coarse fish in good condition, and little harm comes from close-season fishing (which is available in many parts of England). Many anglers believe, however, that fishing pressure is best avoided for part of the year so that the fish have a rest period in which to recover from the effects of angling.