Chemical contamination of fish in the Delaware Bay

I had this interesting and useful email exchange with Bruce Ruppel, an Environmental Specialist 4 with the New Jersey Department of Environmental Protection Office of Science in late February 2014 with regard to chemical contamination of fish in the Delaware Bay. It is reproduced here just for reference. For a more general discussion of seafood advisories in the Delaware Bay, see


Hi Tony, OK, you asked so I’ll give you the whole explanation. It’s complicated but it’s what we know about chemical contaminants in fish. The first thing that you should know is not all chemical contaminants are alike. The organo-chlorinated contaminants (i.e., PCBs, pesticides, etc.) are chemical that are lipophilic. That means that they attach to fat (lipids) tissue in the body, and in fish they tend to be found in highest concentrations in species with high fat content (like bluefish, carp, catfish) and the fatty portions of the fish (dark meat, skin, back strap and belly flap). Mercury is not lipophilic but binds to the fish tissue though out the fish body, so the levels are pretty much the same anywhere in the fillet. There are other chemical contaminants, but these are two groups that make up the majority of our advisories. Eating the fillet portions rather than the whole fish can reduce the amount of contaminant exposure, but the fillet should be properly trimmed by removing those areas where these contaminants concentrate, that is the lateral line (dark meat), the skin, back strap and belly flap. As I mentioned these areas in the fish fillet, along with the head and rack are where the PCBs and pesticides will accumulate, so removing them BEFORE cooking will reduce the amount of contaminant exposure. Also fish steaks (i.e., cross cut) typically contain those parts that should be avoided, so it’s not a recommended preparation method. This is why we recommend eating only a properly trimmed fillet for those species under the advisory. Also, cooking soups and stews of those species under the advisories using fish heads and racks tends to concentrate the contaminants in the final food item and should be avoided. Unfortunately this method only applies to removing the organo-chlorinated contaminants (i.e., PCBs, pesticides, etc.) and not mercury. Mercury binds to the edible tissue and can’t be removed by cleaning or cooking, so the only way of limiting exposure to mercury is by limiting consumption of those species. Now when it comes to crabs the organo-chlorinated contaminants are typically found in the hepatopancreas (green gland or tomalley) a lipid rich tissue, though mercury can also be in the muscle tissue. Here we recommend cleaning the crabs BEFORE cooking them and we have a pamphlet on how to do that. Most people will steam or boil crabs and then clean them, but when that happens the hepatopancreas will often break and cross contaminate the muscle meat. That should be avoided. Also people will often take the cooking liquid (the concentrate) that they boiled or steamed then in and add it to soups, stews and flavorings. Unfortunately that tends to further concentrate the chemical contaminants in the final food item and obviously should be avoided. All this information is on the website and in the pamphlets under proper cleaning and cooking techniques. As far as the type of fish sample analysis we do for the projects. The fish sample analysis that we do for consumption advisories is an individual skinless, fillet. Some sampling of larger forage fish (i.e., adult menhaden, herring, etc) will be an individual whole body analysis and when dealing with smaller forage fish specimens (i.e., killifish, silverside, peanut bunker, etc) then we’ll use a composite (usually 5 specimens) of whole body to attain enough tissue to perform the chemical analysis. But those methods ae used in an environmental assessment and not for consumption advisories. For blue crabs, we’ll also analyze a composite (again usually 5 specimens) of crab tissue, but here, we’ll analyze the crab muscle tissue separate from the crab hepatopancreas (green gland or tomalley) tissue to obtain enough tissue for the chemical analysis and find out what the contaminant levels are in those tissue types The consumption advisories that you’re reading about are built on these methods of tissue preparation for chemical analysis. As you can see this information is quite detailed and difficult to remember so it’s often ignored and you hear responses like what the locals told you before…. However, this is still the best general advice available. Hope this helps clear it up for you. Let me know if you need more information. Bruce


From: Tony Novak

Sent: Tuesday, February 25, 2014 8:02 AM

To: Ruppel, Bruce

Subject: RE: question about white perch advisory in Delaware Bay

Bruce: Can you please address one other issue: There is a common but undocumented belief that eating only the fillets reduces risk to an acceptable level regardless of published advisories. Yet, as far as I can tell, the tissue sampling testing is done with fillets in other states that publish advisories. I could not find any clarification of tissue sampling procedures in NJ or DE. Can you please clarify whether the testing is done on fillet tissue or whole fish?

Tony Novak

From: Ruppel, Bruce

Sent: Monday, February 24, 2014 3:58 PM

To: ‘Tony Novak’

Subject: RE: question about white perch advisory in Delaware Bay

Hey Tony, Congratulations, you discovered an error in our fish advisory website. The advice for the General Population for white perch from the Delaware River between the Delaware/Pennsylvania/New Jersey borderline downstream to the C&D Canal is “Eat no more than One Meal Per Year” not the Once per week as is on the website. There was an error in the transcription from our Advisory Brochure to the Website update. Unfortunately I was working off the same information as you, until I checked with the brochure and the original report and the error was evident. This “change” makes the white perch advisory consistent with the advice for the remainder of the Delaware Bay downstream from the C&D Canal. Unfortunately that still presents a concern to the people consuming this species… We will re-check the information in both documents to see if there are any other inconsistences’. In addition, we will be reviewing all of the white perch advisories for the full length of the Delaware River to see if there can develop a more consistent advisory for this (and other) species. We’ve found that if the advice is less complicated, the more likely anglers will follow it. We have corrected the website information and want to thank you for spotting that one and hope that it doesn’t present you with any difficulties. Thanks again, Bruce

From: Tony Novak

Sent: Monday, February 24, 2014 1:46 PM

To: Ruppel, Bruce

Subject: RE: question about white perch advisory in Delaware Bay

Bruce: Thanks. That is useful. I tried to provide a brief summary to our marina guests at I will likely update my site with information from your comments. The information I’m receiving on white perch lately is concerning. I understand that larger commercial catches from both the Delaware and Chesapeake Bays have grown in recent years and no recordkeeping of location of catch is required. Consumers in New York and Philadelphia eat these fish presumably without any idea of consumption warnings. Interesting, the most common response from the locals on the Delaware Bay is something like “I’ve been smoking and drinking for 30 years, darned if eating the fish I catch is going to kill me”. Tony Novak

From: Ruppel, Bruce

Sent: Monday, February 24, 2014 12:26 PM

To: Tony Novak

Subject: RE: question about white perch advisory in Delaware Bay

Hello Mr. Novak, Thank you for your inquiry. The current advisories are based on specific data collected from locations along the length of the Delaware River/estuary by the States of New Jersey, Delaware and Pennsylvania, as well as the Delaware River Basin Commission. The changes in the 2013 geographic delineation of the fish consumption advisories for the lower Delaware River/Estuary are based upon data generated by the 2012 State of Delaware sampling effort. Samples were collected at the various reaches as defined in the report attached. The previous consumption advisory for the reach of the Delaware River from the borderline of Delaware/Pennsylvania/New Jersey downstream to the C & D Canal was “Do Not Eat Any Fish”. However, this recent data suggests a reduction of the chemical contaminant loading in this reach and a corresponding change in the advisory is warranted. Unfortunately, the currently available data for other sections of the estuary did not show this same reduction, so no advisories changes were made at that time. Should additional become available advisory modifications would be considered. It should be noted that these consumption advisories are directed toward recreational anglers, which tend to consume more fish from specific locations, and therefore may be receiving a greater exposure. There exists regulatory commercial restrictions through the New Jersey Division of Fish and Wildlife (NJDFW) for harvesting various estuarine and marine fish species but these are primarily gear, season, location and quantity regulations. Currently there is no Delaware estuary locational restrictions for the commercial harvesting of fish based upon fish consumption advisories. However, the commercial harvest in areas with limited consumption advice is of concern. There is outreach information on fish consumption advisories available to the public through the NJDEP website and we are currently underway developing more language and species-specific materials. We continue to work cooperatively with representatives of NJDFW, NJ Dept. of Health and Senior Services and NJ Dept. of Agriculture and the corresponding agencies from sister states to develop and revise fish consumption advisories and outreach information as data become available and will forward your concerns on commercial harvesting of restricted fish from the Delaware Estuary. If you have any additional questions please feel free to contact me. Again, Thank you for your inquiry and information. Sincerely, Bruce Ruppel Environmental Specialist 4 NJDEP, Office of Science

From: Tucker, Terri

Sent: Monday, February 24, 2014 8:35 AM

To: Ruppel, Bruce Cc: Buchanan, Gary Subject:

FW: question about white perch advisory in Delaware Bay Can you respond to this question? Thank you.

From: Tony Novak

Sent: Sunday, February 23, 2014 3:27 AM

To: Tucker, Terri

Subject: question about white perch advisory in Delaware Bay

Terri: Do you have any more information about the safety advisory for white perch in the Delaware Bay? The current advisory at is puzzling in that the general population advisory north of C&D canal is one meal per week and the advisory south of the canal is one meal per year. That’s quite a dramatic difference for a small change in location. It’s really confusing to a consumer who isn’t exactly sure where his meal was caught. IMO, also likely to be of growing concern as watermen in Delaware Bay and elsewhere report that white perch are growing in commercial importance. Do you know when those recommendations were adapted and whether re-sampling in in the works? I presume the advisory is based on PCBs? Is there any other published information you can point to? Thanks, — Tony Novak

One thought on “Chemical contamination of fish in the Delaware Bay

  1. This week Mr. Ruppel answered a question I posed about apparent discrepancies between implementation of warnings in commercial vs. recreational consumption. I do not fully understand the explanation given or the logic behind it that is apparently based on the premise that a buyer of commercial fish has less overall consumption of toxins than a recreational fisherman. I don’t see it, especially when ingestion is affected by cooking methods. For example, a consumer who buys fish a few times per year to make fish stock (soup) may consume more organic toxins than a recreational fisherman who eats fillets from fish he catches every weekend. Apparently the different regulatory authorities (commercial fishing is under federal regulations) accounts for some to the difference in consumer advisories. No warning exists for consumers who buy perch from a commercial market.

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