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December 05, 2016
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Studying American shad

Unusually cold temperatures during the second weekend in October resulted in migration to warmer waters, with only 51 shad sampled at Milford Beach on October 12, down from 5,800 when the same site was sampled in August. Three nights later, only six shad were retrieved at the seining site near the Zane Grey Museum in Lackawaxen, PA.

So far, the counts look promising. “The low numbers aren’t indicative of a drop in the population, but rather what we would expect to see with the change in weather and water temperatures,” explains Myers. “After the high numbers we had in August and September, the population index was shaping up to be the third best overall index for non-tidal sampling done from 1981 to present, and the September 2012 index was the second best September ever. With the addition of our October hauls and the drop-off that we saw due to colder water temperatures, it dropped the 2012 index to being ninth-highest overall (from 1981 to present).”

For more information contact Myers at jamie_myers@nps.gov or 570/729-7842.

About American shad:
American shad are an anadromous species indigenous to the Delaware River and the entire Atlantic Coast. Each spring, adults return to their natal waters to spawn. YOY shad remain in the river through summer and migrate downstream and out of the river in the fall. In the Delaware River, spawning occurs throughout the upper 318 km of non-tidal waters, which extend from Trenton, NJ to Hancock, NY. Three national parks encompass 77% of these waters. Maintaining viable populations is essential to the ecosystems of the Lower Delaware National Wild and Scenic River (LODE), Delaware Water Gap National Recreational Area (DEWA) and Upper Delaware Scenic and Recreation River (UPDE). In the 1890s, the Delaware River had the largest shad harvest of any river along the Atlantic Coast. Factors responsible for the current decline are unknown, but could include riverine habitat change, increased predation and excessive fishing-related mortality on adults. A monitoring program will also help to determine if shad populations are affected by reservoir releases.