In-seine in the Membrane


By: Rebekah Bergkoetter, Western Region Biologist

Despite its large size, the California tiger salamander (Ambystoma californiense) is a beautifully elusive species. The adults will spend the majority of their lives underground in burrows, making them quite difficult to observe. Fortunately for amphibian lovers at Westervelt Ecological Services (WES), these salamanders emerge in the late fall and early winter, after the first rainfall, to make a pilgrimage to the nearest waterbody to breed. Within their habitat, these waterbodies typically consist of vernal pools and large ponds. While it may still be difficult to catch sight of a fully grown adult, we can observe and study the population by sampling pools and ponds for larval salamanders.

As a federally-listed species, special permitting is required to handle these animals, and careful protocol must be followed. Under the supervision of a permitted biologist, sampling in vernal pools and ponds may occur; the sampling may consist of dip netting or seining. The process of seining a pond requires careful timing and teamwork. To seine a pond, two biologists will hold a large mesh net between them and walk forward 10-20 feet, while gently pulling the net across the bottom. However, some features may be too deep to walk through. In these cases, at least two more biologists and a boat are required.

Recently staff from WES’s Sacramento office performed this boat seine technique on a property in search of California tiger salamander larvae. Armed with paddles, life vests, and a seine, two biologists rowed a boat to the deepest section of the pond and dropped in the one end of the seine. With a little paddle forward the other end of the seine was deployed. Each end of this seine was secured to ropes held by two more biologists who waited on the shore. Once the seine was deployed the shore biologists pulled it back as the boat biologists paddled to shore to help. Once the seine was brought to the shore, everyone worked quickly to identify species before they were returned unharmed to their habitat. And on a sunny day in April, we identified tadpoles for California red-legged frog (Rana draytonii), Pacific treefrog (Hyliola regilla), California toad (Anaxyrus boreas halophilus), and the much desired California tiger salamander larvae.



Boat launch


Deploying the seine


Walking seine


Juvenile tree frog


California tiger salamander larvae