Chesapeake Bay Shad Recovery Uneven

There are two stories in the news today about shad populations in Chesapeake Bay, using the same data, and coming from a different angle. The report from the EPA Chesapeake Bay Program stresses the evidence of recovery as sign that things are getting better:

Shad abundance surpasses restoration goals in Potomac, Rappahannock

Shad abundance has surged in four Chesapeake Bay rivers, surpassing restoration goals in the Potomac and Rappahannock. While shad populations are critically low along the Atlantic coast, scientists hope to see rising trends continue in these two waterways. Shad spend most of their adult lives in the ocean, migrating into freshwater rivers and streams to spawn. Their return brings food to the Bay in the form of protein-rich eggs, adult shad that can be captured during the spawn and a new generation of shad that can offer forage to striped bass, bluefish and other species as they return to the sea.
. . .
Between 2000 and 2014, shad abundance in the Bay increased from 11 percent to 44 percent of the goal. The Potomac River has seen the most consistent rise in returning shad, but the Rappahannock has also seen notable highs. In 2014, abundance in the Potomac and Rappahannock reached 130 and 110 percent of the rivers’ respective targets.

Notice the Susquehanna on that chart. It's not going so well there. This was noticed by B-More Green, the Baltimore Sun environmental blog: Once nearly wiped out, shad stage an uneven comeback in the Chesapeake Bay

Once severely depleted, American shad - the fish that fed the nation's founders - are finally making a comeback in the Chesapeake Bay. Their return so far has been uneven, though.

Spawning runs of the migratory fish have surpassed restoration goals in two of the bay's major tributaries, the Potomac and Rappahannock rivers, the Chesapeake Bay Program announced Friday. Shad numbers have shown varying gains in a couple other Virginia rivers, but they remain scarce in the bay's largest tributary, the Susquehanna, as well as in the upper James River.

I know that the fish ladders at Conowingo dam are part of the problem, but it seems to me unlikely that they are the entire issue:

A lift installed in 1997 at Conowingo dam on the lower Susquehanna seemed to be working at first, helping nearly 200,000 spawning shad upriver in 2001. Shad traffic declined after that, though, and hit an all-time low of 10,000 last year. And only eight shad made it all the way past the four dams on the lower Susquehanna.

This year's Susquehanna shad run has only recently begun, so it's hard to tell if it will fare any better than last year's. As of earlier this week, the Conowingo fish lift had helped 4,465 American shad upriver, according to Exelon Corp., the operator of the hydroelectric dam there.

Are we to think that shad got even more stupid between 2001 and 2014.

Shad cam!