Largemouth BassMicropterus nigricansMissä ja milloin niitä voi nähdä

The largemouth bass is a freshwater predatory fish native to North America and a member of the sunfish family, Centrarchidae. Introduced widely outside its native range, it is established in Portugal, including the Douro basin. It is particularly associated with reservoirs and sheltered stretches of slow-moving water. Although valued as a sport fish, this non-native predator can affect local wildlife through predation and competition. Many older references list it as Micropterus salmoides, a name now applied to the Florida bass under revised taxonomy.

Size

Typically 25–50 cm long; large individuals can exceed 60 cm.

Weight

Commonly around 0.5–2 kg; large individuals can exceed 5 kg.

Lifespan

Often around 10 years, with some individuals reaching 16 years or more.

Status

Least Concern

Largemouth bass usually hunt by waiting near cover and making short, powerful attacks on passing prey. They also patrol shorelines and the edges of vegetation when conditions are suitable. Activity often increases around dawn and dusk, although feeding can occur throughout the day. In colder water, their metabolism slows and they generally feed less frequently. During spring or early summer, males clear shallow nests on firm substrates. A male guards the eggs and newly hatched young, defending them against potential predators. Larger adults are often solitary, while younger fish may gather in loose groups.

• Despite its name, it belongs to the sunfish family rather than the true bass family.
• The male builds the nest and guards the eggs and young.
• It captures prey partly by rapidly opening its mouth and drawing water inward.
• In Portugal, it is commonly known as achigã.

Wildlife opportunities depend on the river reach, water levels and species. River-specific viewing months have not been confirmed; general species seasons are not a local sighting forecast.

This species favours warm lakes, ponds, reservoirs and slow-flowing river sections. In the Douro basin, impounded waters and sheltered margins provide more suitable habitat than fast-flowing channels. Submerged vegetation, fallen branches, rocks and other structures offer concealment and feeding opportunities. Juveniles often use shallow cover, while larger fish may move between shoreline shelter and deeper water. Water temperature, oxygen availability and changing reservoir levels influence where fish are found.

Largemouth bass are opportunistic carnivores that swallow most prey whole. Young fish initially eat zooplankton and small aquatic invertebrates before taking larger prey as they grow. Larger individuals feed mainly on fish and crayfish, with aquatic insects, frogs and other available animals also taken. Diet varies with fish size, habitat and local prey availability.

Common name

Largemouth Bass

Scientific name

Micropterus nigricans

Animal group

Fish

Size

Typically 25–50 cm long; large individuals can exceed 60 cm.

Weight

Commonly around 0.5–2 kg; large individuals can exceed 5 kg.

Lifespan

Often around 10 years, with some individuals reaching 16 years or more.

Status

Least Concern

Identification

The largemouth bass has an elongated, robust body, usually olive-green above with paler sides and a whitish belly. A dark, often broken horizontal stripe runs along each flank, although its visibility varies. Its most useful feature is the large mouth, with the upper jaw extending behind the eye when closed. The spiny front and softer rear portions of the dorsal fin are joined but separated by a deep notch.