Aquatic Species at Risk - Cultus Pygmy Sculpin

Description
Habitat
Threats
Further Information
Scientific Information

Description
Cultus Pygmy Sculpin is a freshwater fish of is roughly 50 millimeters long in the full grown adult stage. The fish is brown to grey on top, and marked with dark blotches; its bottom is more or less white. Spawning males are darker-coloured and boast an orange band on the first dorsal fin. The species has a large head, a heavy body and small pelvic fins, a long anal fin, two soft dorsal fins, and sizeable fan-like pectoral fins with small prickles behind them. Two or three dark blotches appear beneath the second dorsal fin. Adult fins have bar-shaped pigments.

Habitat
This small fish is found only in Cultus Lake in southwestern British Columbia. Cultus Lake is a low-elevation montane lake that drains into the Vedder River, a tributary of the Lower Fraser River.

Threats
Due to its limited range and isolation, the Cultus Pygmy Sculpin is highly vulnerable to changes to its surrounding environment. Eutrophication (excessive nutrient input) of the lake’s water and the introduction of invasive species to Cultus Lake in particular pose major threats.

Point and non-point source pollution in the form of excessive nutrients can affect water quality and degrade aquatic habitat. In most cases, these inputs come from poorly-performing septic systems, excessive use of agricultural and domestic fertilizers, and sedimentation from poorly-managed land.

The proliferation of invasive species can upset the delicate balance of the Cultus Lake ecosystem. These in turn can drive out the Cultus Pygmy Sculpin through competition for food, or direct predation.

Further Information
Very little is known about the Cultus Pygmy Sculpin. However, various surveys and studies suggest that they reside primarily in the deeper parts of the Cultus Lake (up to 40m). Based on behavior of similar species, it is generally assumed that Cultus Pygmy Sculpin lay egg masses under cobbles or small stones at the bottom of the lake. They are then guarded by males of the species. Breeding likely begins when individuals reach 3 years old, spawning in late May or early June and possibly continuing through the summer. Interestingly, spawning apparently does not occur in tributary streams or in shallow near-shore areas. The fate of newly hatched fry is not known.

There are no reliable data on the population size for the Cultus Pygmy Sculpin. The population size appears to fluctuate seasonally; this could be due to pulses of reproduction, seasonal migration, predation pressures, or other reasons.

The Cultus Pygmy Sculpin was initially assessed as “Threatened” by the Committee on the Status of Endangered Wildlife in Canada (COSEWIC) in 2000 and listed under SARA in 2003. COSEWIC reassessed and confirmed the species status in 2010.

A recovery strategy has been developed by Fisheries and Oceans Canada and the Province of British Columbia. An action plan is now being drafted that outlines measures to support progress towards meeting the population and distribution objective in the recovery strategy, which is to ensure the long-term viability of the Cultus Pygmy Sculpin population in the wild.   Public consultations on the draft Action Plan are planned for November and December 2012.

For more information, please visit the Pacific Region SARA Consultation website or the SARA Registry.

Scientific Information

Scientific Name: Cottus aleuticus Cultus Population
SARA Status: Threatened
COSEWIC Status: Threatened
Occurrence: Cultus Lake, British Columbia