We have been seeing some very interesting views of sticklebacks through pond cam and Heart of Reeds cam. Sticklebacks are very hardy little fish that are often found in ponds and ditches. There are two different types on the reserve, three-spined stickleback and the less common ten-spined stickle back.
The three-spined stickleback is the most common species in the reserve; adults are usually 4-6cm long. The name is due to the three sharp spines on its back (occasionally two or four) which help protect the stickleback from being eaten by predators. The sticklebacks stick their spines up when threatened and even the most ferocious freshwater fish in our rivers, the pike, find sticklebacks very difficult to swallow.
Both the three and the ten-spined stickle back can live in brackish water (a mixture of salt and freshwater) as well as living in freshwater. Some three and ten-spined sticklebacks live in the sea and it is likely that the early ancestors of freshwater sticklebacks were once marine fish. The ten-spined stickleback is similar to the three-spined variety, except that their body is longer and they have 10 spines. We which we have seen through Heart of Reeds cam and also in a couple of the pond dipping sessions.
In the video clip below you can see a ten-spined stickleback in the background and a three-spined stickle back swimming around.
Sticklebacks breathe using gills. Like many other fish, the stickleback has an air filled bladder inside their body that helps to keep them buoyant, so they neither sink nor float to the surface, but can stay at the same depth. They swim using their tail and steer using the pectoral fins. These are the tiny fins on the side of their body, near the head.
Unlike most fish, sticklebacks do not have scales, although some specimens have bony plates. They are in fact closely related to seahorses and pipefish. It’s not surprising therefore that it is the male that looks after the eggs. Unlike the male seahorse and pipefish that look after the eggs in a special pouch, male sticklebacks build a nest from bits of pond weed.
In the spring breeding season, the male has a metallic look and the throat is red to attract a female. We know through our pond cam and reed cam that the male sticklebacks are coming into their breeding colours. The male will chase off any other male sticklebacks, reacting to the red colour of their throat. The female will have a rounded abdomen because of her eggs. The male will perform a special dance to try to entice the female to lay her eggs in his nest.
A female stickleback may lay up to 400 eggs. Once the eggs are laid the female leaves and the male takes over the duties of guarding the eggs against predators and frequently fans the water to create a current, making sure the eggs get plenty of oxygen.
The eggs will hatch about 4 weeks later and the male stickleback will continue to guard the newly hatched fish fry. The fish fry eventually wander from the nest site to fend for themselves. The developing stickleback fry will feed on small pond animals such as worms, insects larva and daphnia. The sticklebacks will face many dangers and many will be eaten by dragonfly larva, beetle larva and other pond predators. We often catch stickleback fry when pond dipping in the Leighside pond and the ditches, so we know that they breed each year.