Is it healthy to eat fish caught in Delaware waters?

Delaware regulators revise “advisories,” say it’s OK to eat more Delaware fish.

A Feb. 20, 2018 press release gives us the usual positive spin.  There’s some truth in it.

Levels of some waterborne toxins are dropping, as they should be, given that some very contaminated sites have been somewhat cleaned up.  These sites tend to discharge toxins such as PCBs, dioxins, DDT, other chlorinated pesticides, and mercury, into waterways.  Also, mercury from coal-burning power plants, “biomass” burners, and garbage incinerators falls out into the water.  Fish take this water in through their gills, absorb some of the toxins, and these end up in their flesh.  Eat these fish, and some of the toxins end up in you.  If you are pregnant they end up in your baby.  Coal burning in Delaware has decreased and, with much effort, we have generally been able to hold the line on incinerators and “biomass” burners.

But the picture is not quite so favorable as suggested by the DNREC press release.

There are, approximately, depending on how they are counted, 30 fish advisories for Delaware waters, including an overall advisory applying to all waters not otherwise listed, all finfish, and all contaminants.  This advisory says not to eat more than 52 eight-ounce servings per year.

Approximately ten of these have been lifted or loosened.  In some cases the guidance is now to eat no more than three servings per year rather than one.  Or six servings per year rather than two.  Or twelve servings per year rather than six.

So, broadly, about one-third of the fish advisories have been relaxed or eliminated.  Details here and here.

In at least five cases, the guidance is still that “Women of childbearing age, and children should not consume any amount of these fish.”  Children means less than six years old and the official serving for them is three ounces not eight.

So should you eat Delaware fish?

Delaware regulators are using a health risk breakpoint of one per one-hundred-thousand.  In other words, factoring in all sorts of assumptions, this would be an acceptable lifetime health risk from eating fish.   Above that, we get an advisory, below that, we don’t.

Delaware also uses an assumed 30 year exposure period, rather than the 70 year period commonly assumed to represent “lifetime” exposure.  This cuts the assumed risk by 2.3 times.  On the other hand, some assumptions used in Delaware could be more cautious.

Because these “human health risk assessments” do involve assumptions piled on top of assumptions they should be viewed with caution.  On the one hand they may use “conservative” assumptions (few people would really eat that much fish …), on the other hand there may be more toxic substances in the fish than are tested for, and the cumulative/synergistic effects of multiple contaminants may be unknown.  There may be unknown toxic effects even from known bad actors, or harm may occur at lower doses than assumed.  Etc.

To be blunt about it, the Delaware Division of Fish and Wildlife is in the business of promoting fishing, and much of it’s revenues come from fishing licenses, etc.  The Division receives federal funds for “restoration” efforts but this does not seem to include cleanup of contaminated habitat.

A technical document describing the Delaware fish advisory program is here.   A Memorandum Of Agreement between the DNREC and the Division of Public Health has been in effect since 1993.  We are still trying to get a copy.   Our impression is that Public Health, unlike some in the DNREC, has never shown much interest in carrying out its responsibilities under this agreement.  In particular, Public Health has not made much effort to put up warning signs.  Example:  The people promoting recreation along the Wilmington waterfront did not want the public to see signs indicating that the water is polluted and fish from the Christina River are unsafe to eat.  So, when signs were finally installed they were put on bulkheads facing out into the river so nobody could see them except from boats.  We understand that the DNREC is taking over responsibility for “signage” and possibly things will improve.  (We didn’t get useful responses from the Division of Public Health.)

On the other hand, many argue that fish is a healthy food.  The Fed 20th press release includes this:

“The improved water quality allowing people to eat more fish caught in local waterways is good news across the board,” said DHSS Secretary Dr. Kara Odom Walker, a board-certified family physician. “Consuming fish is an essential part of a healthy diet because fish contain so many key nutrients, are low in saturated fat and contain omega-3 fatty acids. The updated advisories will help Delawareans make good decisions for themselves and their families about the right kinds of fish to eat from our state’s waterways, as well as the right amount.”

It’s obviously absurd to imply that eating fish is “essential” to a healthy diet.  But eating fish, in general, is likely healthier from a nutritional point of view than eating, say, beef or bacon.  Healthier than rice and beans?   Than a vegetarian or vegan diet?  Opinions will vary.

What-to-eat guidance from government agencies depends as much–often more–on politics as on science.  See, for example, this piece about how the political power of the meat industry, combined with the lack of integrity of academic institutions, keeps cancer-causing chemicals in bacon and sausage.

Red Clay Creek

One recently published report discusses renewed stocking of trout in the Red Clay Creek, a small creek long heavily polluted by industrial discharges in Delaware and Pennsylvania.  This is worth a read for the light it sheds on DNREC’s thinking.  Here’s the Executive Summary in full:

The Red Clay Creek in Southern Chester County, Pennsylvania and Northern New Castle County, Delaware has a long history of water quality problems. Fish contamination from legacy substances such as polychlorinated biphenyls (PCBs) and the pesticide DDT lead to the issuance of fish consumption advisories in the 1980s. These concerns also lead to the discontinuation of put-and-take trout stocking in this same time period. Conditions have improved to the point where advisories are now less stringent and there’s a desire to reintroduce trout stocking to the Delaware portion of the Red Clay. Before that can be done however, the Delaware Division of Fish and Wildlife, in collaboration with the Delaware Division of Watershed Stewardship, studied the uptake of contaminants in stocked trout in 2016 in the area that was historically stocked. The study objective was to assess if contaminants are taken up by the trout after being placed into the Red Clay and if so, how fast, and whether that uptake represents a significant health risk to anglers who may consume their catch. The management objective was to determine the feasibility of reintroduce trout stocking to the Red Clay Creek in Delaware.

Rainbow Trout directly from the hatchery had low concentrations of contaminants. When the hatchery trout were placed into the Red Clay Creek, they immediately began to accumulate and continued to accumulate several legacy contaminants including PCB, DDX, chlordane and dieldrin over the course of the study. The degree of accumulation was found to be a function of the concentrations in the water, streamflow, and the hydrophobicity of the contaminant.

Despite the accumulation of these contaminants, potential health risks to trout anglers can be kept low by moderating consumption ( This can be done by following the existing advice of no more than twelve (12) eight ounce meals of stocked trout per year which currently applies to other trout stocking waters in Delaware (except for the Christina River where the advice is half as much). Hence, it is feasible to return the Red Clay Creek to its former trout stocking status. More correctly, contaminant uptake alone does not prevent the Red Clay from once again joining the rotation of designated trout stocking waters in Delaware.

In addition to moderating consumption, another strategy to limit trout anglers from getting elevated exposures to contaminants in recaptured trout is to stock these trout a little later in the season. Because the trout, especially Rainbow Trout, cannot tolerate higher water temperatures, stocking them later shortens the window of time they can survive in the Red Clay and therefore limits the amount of chemical accumulation these fish will experience. This in turn limits potential exposure to trout anglers.

Is there a rational way to balance the claimed nutritional advantages of eating fish against the exposure to toxic contaminants?   Clearly the DNREC (and, in theory, the Division of Public Health) feels it has found one.  Do you agree?

Changing of the guard

Progress has been made on fish toxicity and two of the main contributors to this effort are retiring as of April 1st:

Rick Greene is retiring from the DNREC after a career of over 30 years.  Rick has always been a key investigator of fish contamination and the sources for same.

Tom Fixlin has had a long career with the Delaware River Basin Commission and, before that, the US Environmental Protection Agency.

Rick and Tom’s work will be taken over by capable people, but both will be missed.

Toxins in commercial fisheries are regulated by the federal Food and Drug Administration under different rules.


What does seem clear is that only a few sites are responsible for a great proportion of the contamination and quicker cleanup of these would make a difference.  These include the Amtrak repair facility in Wilmington, grossly contaminated with PCBs, DuPont’s former Edge Moor plant in Claymont, whose contaminants–PCBs and Dioxins–can be found for 70 miles up and down the Delaware River, DuPont’s (now Chemours?) former (?) Chambers Works site, and of course our good friends the Delaware City Refinery.

Another reality is that recreational and commercial fishers seldom lend much support to environmental cleanup demands.

One thought on “Is it healthy to eat fish caught in Delaware waters?

  1. am Post author

    As a little supplement, here is a presser from DNREC about fishing:


    Contact: Joanna Wilson, DNREC Public Affairs, 302-739-9902

    Upstate trout season to open April 7 in seven New Castle County streams

    DNREC announces Red Clay Creek to be stocked for first time in 30 years thanks to improved water quality;
    trout anglers also should note that changes have been made to original stocking schedule

    DOVER (March 14, 2018) – Delaware’s spring upstate trout season will open at 7:30 a.m. Saturday, April 7, DNREC’s Division of Fish & Wildlife announced today. Portions of seven designated trout streams in northern New Castle County – White Clay Creek, Red Clay Creek, Christina Creek, Pike Creek, Beaver Run, Wilson Run and Mill Creek – will be stocked with thousands of rainbow and brown trout, including some trophy-sized fish. Trout stocking will continue weekly in April at White Clay Creek and periodically at the other streams prior to or until Thursday, May 3.

    The designated trout streams are closed to all fishing two weeks prior to opening day, starting Saturday, March 24. The preseason closure allows stocking to be completed and eliminates incidental trout-hooking mortality and unlawful harvest of trout by those who are fishing for other species prior to the opener, while also giving stocked trout time to adjust and spread out in their new waters to improve fair access to the fishery. Following the 7:30 a.m. start opening day, trout fishing at these steams is permitted one half-hour before sunrise to one half-hour after sunset.

    Improving water quality conditions have enabled the Division of Fish & Wildlife to stock a short stretch of Red Clay Creek that has been closed to fishing since 1986. Anglers are asked to stay clear of marked construction zones. Some trout will be stocked from the dam located near the Pennsylvania state line downstream to the bridge at Benge Road. The first stocking will occur Monday, April 9, at which time anglers may fish as soon as the fish are stocked.

    Downstate trout season remains in full swing at Tidbury Pond near Dover and Newton Pond near Greenwood, both of which opened March 3. Trout are a cold water species and survive only while water temperatures in the ponds remain cool, so anglers are encouraged to keep their catch.

    A Delaware fishing license is required for most anglers fishing for trout. In addition, most trout anglers also must purchase a Delaware trout stamp. For residents age 16 through 64, a trout stamp costs $4.20. For residents age 12 through 15, a young angler trout stamp costs $2.10. Resident anglers younger than age 12 or age 65 and older are not required to purchase a trout stamp. For non-residents, a trout stamp is required for all anglers age 12 and older and costs $6.20. A trout stamp is not needed after April 1 to fish at Tidbury Pond and Newton Pond or after June 30 to fish in the upstate trout streams.

    Delaware fishing licenses are sold online, at the licensing desk in DNREC’s Richardson & Robbins Building, 89 Kings Highway, Dover, DE 19901, and by license agents statewide. To find a participating agent, or to purchase a license online, visit Delaware Licenses. For additional information on Delaware fishing licenses, call 302-739-9918.

    For more information, including the revised stocking schedule, click Delaware Trout Season. For general information on fishing in Delaware, click 2018 Delaware Fishing Guide. The guide also is available in printed form at DNREC’s Dover licensing desk, and from license agents throughout the state.

    All proceeds from the purchase of Delaware Trout Stamps are used to help purchase next year’s fish for stocking. This popular fishery also is supported by Federal Aid in Sport Fish Restoration funds generated from anglers purchasing fishing equipment.

    Follow the Division of Fish & Wildlife on Facebook,


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