Hey JD, do you have any input regarding a theory that the non-indigenous Stripers may have a contribution to the current downturn in several indigenous species (i.e. Pacific Coast Salmon, Delta Smelt) populations?
–Don B.
Don, while stripers do dine juvenile salmon, there’s no evidence that suggests that they have big impact on salmon populations. Though non-native, stripers have been coexisting with salmon for 150+ years. In surveys of predators conducted in the Delta recently, Delta smelt have not been found in the stomachs of striped bass and in fact, stripers may actually help Delta smelt by preying on fish that like to eat smelt.
Nope, stripers are not the cause of all this. The main problem with the smelt is poor water quality in the Delta. caused mainly by epic water diversions. Back when we had big numbers of salmon and smelt, the striper numbers were also high…everything has collapsed since record water exports started a few years ago. The salmon are influenced by poor water quality though the major cause in their decline has been lousy ocean conditions.
Dave says
No doubt stripers do eat juvenile salmon and steelhead–but they also consume large amounts of other fish as well– among them the “pike minnow” (or squawfish, hardheads etc).
I once read a study on predation on salmonids in the Columbia River basin by smallmouth bass.It turned out that where smallmouth were introduced there was NO EFFECT on salmon numbers and on several streams salmon numbers actually increased. The reason for the ‘surprise’ outcome was that bass actually consume large numbers of pike minnows and other fish that prey heavily on both salmon eggs and juvenile salmon.
I suspect that because stripers (unlike smallmouth) are migratory their net impact may be less than the pike minnows they consume (which not only feed on juvenile fish, but also eat plenty of eggs since they are in the rivers all year).
More on Pike Minnows and their impacts:
http://www.pikeminnow.org/info.html
I haven’t seen in California studies, but I would not be surprised to see a similar effect.