Bluntnose shiner  (Notropis simus)

The bluntnose shiner is classified as Endangered (EN) on the IUCN Red List (1).

The bluntnose shiner (Notropis simus) is a small, freshwater minnow belonging to the Cyprinidae family (3), a diverse group of fish comprising over 2,000 species (4). It is silvery with a grey to green-brown underside, and is characterised by a scattering of melanophores (pigment-containing cells) on its head and sides.

This species’ common name, bluntnose shiner, refers to the ‘shimmering’ silver streak that runs from the head to the tail, as well as its distinctive blunt snout. Interestingly, during the spawning season, the male bluntnose shiner develops very small tubercules on its head and pectoral fins (3) (5).

Today, the range of the bluntnose shiner isrestricted to approximately 300 kilometres of the Pecos River in eastern New Mexico (6). However, historically the subspecies Notropis simus simus, which is now unfortunately extinct, was also found in the upper Rio Grande of Texas, New Mexico and Mexico (1).

The bluntnose shiner is found in main river channels, at depths of 17 to 41 centimetres, where the substrates are shifting sand and small gravel (3) (5).

The diet of the bluntnose shiner is believed to primarily consist of algae, terrestrial invertebrates and detritus (3). The maximum lifespan of the bluntnose shiner is about three years (7); however, most individuals are unlikely to survive for more than two years (5).

The spawning season of the bluntnose shiner extends from May to September. However, it is not known whether individuals spawn several times each season or just once.The bluntnose shiner is a pelagic-broadcast spawner, meaning the eggs and sperm are released into open water for external fertilisation.

Spawning behaviour begins with the male pursuing a female and nudging the female’s abdominal region. Once the female is ready to spawn, the male wraps around the female’s body and fertilises the eggs as they are released. The eggs are semi-buoyant, causing them to be dispersed widely by the water current. The eggs develop rapidly, hatching into larvae within 24 to 48 hours after fertilisation (8).

A study by the University of New Mexico showed that numbers of the bluntnose shiner had reduced significantly between 1939 and the 1990s (3). Several factors have contributed to this decline. Most importantly, the construction of dams and reservoirs has blocked the upstream movements of the bluntnose shiner into formerly occupied habitats (5). Water degradation from agricultural pollutants has also reduced numbers (3).

In addition, changes to the Pecos River channel from the building of canals, as well as the increased growth of non-native plant species, mainly tamarisk (Tamarix pentandra), has reduced the suitability of some stream reaches for the bluntnose shiner (5).

The bluntnose shiner was listed as Threatened by the US federal government in 1987, facilitating the introduction of a five year research program to look at the measures necessary for the protection of the remaining populations (5).

This has led to strict maintenance of the water released from reservoirs along the Pecos River, to make sure there are no large, ‘block’ releases of water into the river and the water flow remains semi-natural. This should reduce the negative effects of changing water levels on the life history stages of the bluntnose shiner. The program has also enabled research into the effect of non-native fish and water quality on the bluntnose shiner. The goal of this research effort is to hopefully conserve the remaining bluntnose shiner population and the native fish community of the Pecos River (5).

Find out more about the conservation of the bluntnose shiner:

• U.S. Fish and Wildlife Service:
  http://ecos.fws.gov/speciesProfile/profile/speciesProfile.action?spcode=E04F

Learn more about the conservation of the bluntnose shiner’s habitat:

• Pecos River Open Spaces:
  http://pecosriveropenspaces.org/