Shad State of Affairs, Part Two: Swimming With Mackerel

Image: Maryland Department of Natural Resources

Here's some advice for American shad (who are not a huge part of this blog's readership, but nonetheless): Beware of the striped bass, and stop hanging around mackerel. This week's excellent article by Sandy Bauers in the Philadelphia Inquirer—"Where Are The Delaware River Basin's Once-Legendary Shad?"—expands the conversation about shad and examines some reasons why the native fish aren't yet ascending the fish ladder at the Fairmount Dam on the Schuylkill by the hundreds of thousands each year (more than 3,000 passed through in 2011, part of an upward trend in recent years). It turns out there are other fish in the sea:

As a whole, the East Coast population of American shad is considered "depleted."

Scientists working to restore the shad are finding that everything is connected. Among the reams of charts and data sets is one showing that as striped bass numbers have increased, the population of shad - their juveniles often prey of striped bass - has fallen. The lines on the chart look like a big X.

In recent years, attention widened to what was happening offshore, where shad spend four to six years growing to maturity. It turned out that they school with Atlantic mackerel, then wind up snared in the nets of fishing trawlers.

If and when the shad return in great numbers, the fish will find improved water quality in the Delaware and Schuylkill rivers, dams removed and fish ladders built, including the one operated by the Philadelphia Water Department and the Army Corps of Engineers at Fairmount Dam.

Previously:

Life Aquatic: American Shad

We've Been Shad

Northwest Passage: Fairmount Fish Ladder Helps Shad Swim Up The Schuylkill

A Shad State of Affairs

Upstream Battle: Shad Ascend Schuylkill Past Phoenixville for First Time in Almost 200 Years