MARTINEZ, Calif. – Last week, another species of fish was spotted migrating up Alhambra Creek near Ward Street. The rare sighting is the second of its kind since January of this year, and is a positive marker for the local watershed.
While the January sighting was identified as a single Steelhead, the larger school of fish seen Saturday, April 13, were Sacramento Suckers. Several sightings of the suckers have since taken place in the pools near Ward Street.
The suckers are a native species of minnow. The hearty fish that thrives in warmer, muddier water, can easily reach over a foot long. According to Michelle Leicester, a biologist with the Department of Fish and Wildlife, these fish usually prefer deep pools and undercuts common in reservoirs.
“More than likely, they will be able to complete their spawn and return to their pool habitat before flows drop too precipitously,” Leicester said.
But why the sudden reappearance of migrating fish? There’s some speculation it may be due to the absence of beaver dams in the creek.
“It’s a grey area,” said Gordon Becker, senior fisheries scientist with the Center for Ecosystem Management and Restoration (CEMAR). “If you have a narrow channel and good engineers (beavers), it’s possible passage could be restricted.”
After the deaths of several young beavers and the apparent absence of adult beavers that once populated the area, the City removed the dams and dug deeper channels throughout the creek last October. The alterations were performed in the hope that predicted El Nino rains wouldn’t flood the downtown business district. Since that time, no beavers have been spotted in Alhambra Creek, but more fish have begun to appear.
It’s Leicester’s view, however, that the migrating Sacramento Suckers may have benefited from the beaver dams.
“My guess would be that the beaver dams likely created very productive pools that provided plenty of food and forage for them, allowing them to both grow and amass enough energy to be able to mount a spawning run like this one,” she said. “It is hard to say with any accuracy what really triggered the spawning after so many years, as these fish have obviously been present all along.”
Becker reiterated that while the dams may have blocked upstream passage for fish, there are many benefits of wood in streams.
“It’s a problem regionally that people look at wood in the streams as necessary for automatic removal, and it’s important for people to consider the function of wood in the stream,” Becker said. “Sometimes there’s over-aggressive clearing of wood which wouldn’t necessarily cause flooding, but people are erring on the side of caution when removing it from waterways. Hopefully, local flood control folks are paying attention to when wood should stay in the creek and when it should come out.”
Meanwhile, beaver advocates such as local organization “Worth A Dam” continue to highlight the fact beavers are a keystone species, or a species upon which other species in an ecosystem depend. During the beaver’s reign in Martinez, wildlife such as mink, hooded merganser and river otter have been spotted in Alhambra Creek. The organization encourages the public to keep an eye out for the beloved mammal, which they hope will return to local waters.