Why is the unarmored threespine stickleback endangered

According to Aquarium of the Pacific, three-spine sticklebacks have recently become a major research organism for evolutionary biologists trying to understand the genetic changes involved in adapting to new environments. Scientists believe that the many different stickleback populations in the northern hemisphere all emerged from a common marine ancestor.

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The fountain, mural and accompanying graphics illustrate the story of our Los Angeles and San Gabriel Rivers. Although not on exhibit in the Aquarium, this fish is included in our website animal database to expand on the information touched on in The Wave Fountain exhibit.

Once common throughout the Los Angeles, California basin. Although most species of stickleback can adapt to salt, brackish, or fresh water, unarmored threespine sticklebacks appear to be limited to fresh water. They require clear, flowing, well-oxygenated water with associated pools and eddies of quiet water and areas of dense vegetation or debris to provide adequate cover and food supply.

Threespine sticklebacks are laterally compressed, fusiform shaped fish with three sharp, erectile spines at the forward part of the dorsal fin. The pelvic fin usually consists of a spine on each side and one fin ray. Modified scales form a single row of armor-like plates along the length of the body. Sticklebacks have black to dark olive backs with silvery white sides and white to gold bellies.

At spawning time males develop a red throat and belly, the usually clear fins take on a green hue, and the eyes become blue. Females develop a light red or pink throat and belly. This subspecies may reach a length of 58 mm 2.

Females tend to be slightly larger than males. Sticklebacks are voracious omnivores and feed on a variety of food including some algae and invertebrates such as insects, snails, small crustaceans, and some types of small worms. Males sometimes feed on stickleback eggs that are not properly guarded. Because they are visual feeders, they require relatively clear water in order to see their food source. A male first establishes a selected territory that he vigorously protects.

He then excavates a small depression in the sand in which he builds a nest out of fragments of aquatic plants, strands of algae, twigs, and debris. After cementing the materials together with mucus threads spun from his kidneys, he burrows through it to make an exit and entrance and weights down the nest with pebbles.

While building the nest he aggressively defends it against other males and not-as-yet welcome females. Courtship begins when the nest is ready. Next he searches for a receptive female. When a female carrying eggs enters his territory the male swims near her in a zigzag dancing movement. If the female is attracted, she follows him to his nest where she deposits her eggs. The male immediately fertilizes them and drives the female away.

Over the course of the breeding season, the male may entice several other females into his nest. The male protects the eggs and the fry from predators.

They feed primarily on benthic insects, small crustaceans, and snails. The primary threats to the unarmored threespine stickleback are urbanization, eutrophication excess nutrients , stream channelization, groundwater removal, and reduced water quality.

Recent prolonged droughts from to have significantly impacted the year-round freshwater levels of pools and streams and creeks. A number of federal and state agencies have identified critical habitat for the unarmored threespine stickleback in Los Angeles County. Introductions were undertaken by the California Department of Fish and Wildlife in the Santa Francisquito Creek in to increase the range of the species.

Where can you spot it?