In a recent column, I wrote that ospreys eat fish other than menhaden. That brought a response from Dr. Bryan D. Watts, director of the Center for Conservation Biology at William and Mary in Williamsburg, Va. He was kind enough to send me the result of a study conducted by his center that sampled 2,886 osprey pairs from 65 study areas across 10 states.

Within Chesapeake Bay, breeding performance in ospreys has been poor for several years due to extreme food stress during nesting season. The primary objective for conducting the broader study is to see if ospreys are experiencing reproductive deficits in waters beyond Chesapeake Bay.

The annual breeding performance to maintain a stable osprey population is between 0.8 and 1.3 young per pair. The data included in the report came from a variety of institutions and conservation groups. The report was focused on breeding outcomes. That is to fledging stage.  

Breeding performance was determined by salinity. Fifteen study areas were freshwater and 50 in saltwater. Those in freshwater produced an average of 1.15 young per pair compared to only 0.59 young per pair in salty or marine systems.

Regions along the coast that are experiencing reproductive deficits include Chesapeake Bay, the Atlantic coasts of Delaware and New Jersey, outer Long Island, the Connecticut coast north of the Quinnipiac River and the coastal systems between Narraganset Bay in Rhode Island through Buzzards Bay in Massachusetts. The Atlantic Coast of the Delmarva Peninsula in Virginia is not shown because the population has collapsed by more than 90% over the past 20 years. 

Regions that produced good productivity include the Hilton Head Island in South Carolina, the southern coast of Connecticut and the offshore islands of Nantucket and Martha’s Vineyard in Massachusetts.

While many factors can cause nest failures for ospreys, in the Chesapeake, it is the loss of menhaden that has caused young birds to starve to death in their nests. In some parts of Chesapeake Bay, the rate of delivery of menhaden to the nests has resulted in a decline of more than 80% since the 1980s. This reduced rate of menhaden delivery to nests has lowered energy content of the diet by 50%.

Ospreys have recovered from the lows caused by the DDT pesticide crisis. The North American population has surpassed historic benchmarks largely because pairs have colonized reservoirs created within inland areas. Ospreys appear to be secure throughout much of their range but are struggling within some coastal sites. 

There are still many of us who remember when Lewes was the most productive fish processing town in the Untied States. The fish that gave Lewes that title was the menhaden.

Ottis Smith owned the menhaden processing plant in Lewes and employed quite a few of the local men to man the boats and the factory. I believe he was also the mayor at some point.

The main thing I remember about Lewes back then were the flies. No one came here to lounge on the beach if the wind was blowing from the fish factory. When I was in high school, I did come down here for a big bonfire party on the beach. It was lots of fun if you stayed on the smoky side of the fire. 

Then the menhaden collapsed. No fish, no factory. No flies.

By the time I returned from the Navy in 1965, Lewes was the place to be. The old pier was now a fishing pier and part of Cape Henlopen State Park. My mother’s friend Art had a camper near Lewes and fished Roosevelt Inlet on a regular basis. He was far from alone.

So, let’s say the menhaden are about to collapse again. They did it before, and I am sure they will do it again. All fish do. Just look at striped bass and weakfish.

If the menhaden are almost gone, how will the coastal population of ospreys survive? I believe they will. There will be far fewer of them, and they will have very little competition for the available food, but the few that are here will survive. Perhaps they will join their inland brothers and begin to prey on the many ponds we have on Delmarva. Maybe the various state agencies will begin to stock gizzard shad in those ponds to give the ospreys something to eat with a high energy content.

I have been involved in fishery management since the mid-1970s. Back then, I thought people could manage fish. It took a while, but I have learned the fish are going to do what fish are going to do. All we can do is try to conserve a species when the overall population reaches rock bottom, or some greedy entity will kill the very last one.