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Maryland State Government Maryland Department of the Environment

Fish Kills in Maryland

The Department asks that individuals who see an accumulation of dead fish in Waters of the State report it through any of the contact numbers below.

Maryland Department of the Environment
Science Services Administration
Fish Kill Investigation Section
416 Chinquapin Round Road
Annapolis, MD 21401

Normal Work Hours (8:00AM - 4:30PM, Monday - Friday): 1-800-285-8195

After Hours (Toll Free): 1-877-224-7229 or 1-866-633-4686 

Other MDE Emergency Numbers to use for Reporting Pollution Problems

 


December 2010 fish kill involving Norfolk Spot at Sandy Point State Park (Photo: Md. DNR- Park Service)The Maryland Department of the Environment is mandated by the State's Environmental Article Section 4-405 (c) to oversee the investigation of fish kill incidents throughout the State.

The Fish Kill Investigation Section manages and coordinates the multi-agency, statewide fish kill response program.  Staff is on call during the regular workweek and on weekends, holidays and after normal working hours to ensure that all fish kill reports are promptly addressed.

May 2000 fish kill involving Blueback herring at Port Deposit (Photo: MDE)The presence of dead or distressed fish may indicate that a toxic substance has entered the waterway.  For this reason, it is very important to quickly ascertain the facts, announce the findings, and institute corrective measures if practical.

Fish kills also result from a combination of natural and human induced stresses in the environment. Several elements may combine and act synergistically to overload stress tolerance levels and induce a fish kill. Typical stress factors may include population stress (crowding), spawning stress, reduced food abundance, excessive temperatures or sudden temperature change, parasite burdens, high or low pH, low oxygen levels caused by sewage or excessive algae (fueled by nutrient enrichment), salinity stress, chronic toxin levels (including metals and organics), and drought. Each incident is categorized according to the dominant stress factor detected.  

Reported Fish Kills in Maryland


Staff Biologist performing a necropsy on a white perch affected with a bacterial infection (Photo: MDE)A total of 97 fish kills were reported in 2012: below the long term average of 115.  Near record freshwater inputs into Chesapeake Bay in September 2011 (Tropical Storms Irene and Lee) resulted in the removal of the summer “dead zone” and an unusually low number of fish kills for that year (only 70 in 2011).  In 2012, the nutrients associated with those storms eventually led to early, dense, and widespread blooms of the dinoflagellate Prorocentrum minimum in the Bay and tributaries, especially from Annapolis north into the Patapsco River.  The die-off of those blooms in late May triggered numerous fish kills in May and June.

 Sixty eight of the ninety seven reports were considered significant enough to warrant on-site investigations.  There were approximately 158,376 fish mortalities recorded.  This total represents the thirteenth lowest annual total recorded in the last 29 years and is roughly 11% of the average.  Single events usually dominate the total number of fish killed each year.  For instance, in the 1980’s large schools (many in the millions) of young-of-year (yoy) menhaden were involved in several exceptionally large events as a result of corralling in shallow, oxygen depleted headwaters.  In 2012, no fish kills involved such large numbers, however over 100,000 fish of combined species collectively died in the Patapsco River and its tributaries after the massive algal die-off in May. 

Four fish kills in Maryland involved more than 10,000 animals.

The largest kill occurred May 20th in Marley Creek and downstream into Curtis Creek in Glen Burnie.  Approximately 39,000 fish, mostly Atlantic Menhaden died.  Ten other species were also found dead in lower numbers.

The second largest event occurred May 24th in Northwest Harbor in Baltimore City from Canton to Light Street.  Approximately 25,000 fish, primarily Atlantic Menhaden, died in this area over a several day period.

The third and fourth largest kills occurred May 22 and 24th in the Patapsco River, both near Sparrows Point and Masonville Cove.  Each event was estimated to involve 10,000 Atlantic Menhaden.

Over the span of ten days, more than 100,000 fish died in several events in the Patapsco River area.

The fifth largest kill occurred May 27th in Stony Creek, Glen Burnie.  Approximately 9,188 fish comprising five species died as a result of low dissolved oxygen after the spring bloom die-off.

 

Probable Causes of Fish Kills, 1984-2012

 2012 Fish Kills Probable Cause

No kills in 2012 were associated with blooms of the toxic dinoflagellate, Karlodinium veneficum.  K. veneficum is a long term resident of Chesapeake Bay. Although previously thought to be a non-toxic species, Gyrodinium estuariale, it was associated with fish kills for many years.  Over the last decade, researchers at the University of Maryland Center of Marine Biotechnology (COMB) corrected the misidentification, successfully isolated potent chemicals (i.e. ichthyotoxins called karlotoxin) released by the algae, and did basic research demonstrating it’s effects.  Since 2002, this office has worked to combine pertinent data from fish kill investigations (phytoplankton community, water quality, COMB karlotoxin analysis and dose response data) to diagnose kills caused by karlotoxin.

On average, three fish kills per year are attributed exclusively to karlotoxin or to the synergistic effects of low dissolved oxygen and gill damage resulting from sub-lethal concentrations of karlotoxin.  No known human health effects are associated with these phenomena.

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2012 Fish Kills by Habitat 

2012 Fish Kills by Habitat

Fact:  Fish kills occur in all habitats.

 

2012 Fish Kills by County 

 2012 Fish Kills by County

 * Totals do not include fish kills reported in neighboring states or DC

 

Fact: Fish kills are reported from every county of the state.

   

Locations of Tidal Fish Kills, 2012

2012 Tidal Fish Kills

 

Natural Caused Events

Natural causes of fish kills include low Dissolved Oxygen (DO), thermal stress, disease, spawning stress, stranding and other factors.  

2012 Natural Caused Fish KillsBack to top

 

Pollution Caused Events

September 2006 fish kill in Gaithersburg caused by the accidental emptying of a stormwater management pond into a creek (Photo: Intense local pollution or other direct anthropogenic causes were implicated in 7 Maryland events, killing approximately 5,242 fish, 79 amphibians, and 3,500 oligochaete worms.  All of the pollution-caused kills were referred to the appropriate enforcement agencies for follow-up procedures.

 

 

 

 

These kills are presented below, ranked from highest to lowest magnitude of fish mortalities:

·        The largest occurred April 19th in Booze Creek in Bethesda, Montgomery County.  Approximately 2,636 fish comprising sixteen species died after spring rains followed a period of dry weather.  After an exhaustive investigation by MDE and Montgomery County biologists and enforcement personnel, it was determined that three fish kills had occurred in the area, all with contiguous but discrete watersheds.  Another three fish kills occurred elsewhere in the county the same day.  The most probable cause of these kills was non-point source urban runoff.

·        The second largest occurred April 19th in Croyden Creek a tributary of Rock Creek in Rockville, Montgomery County.   Investigation revealed that 1,516 fish (3 species) and 2000 oligochaete worms died after spring rains followed a period of dry weather.  During investigation, it was determined that another fish kill had occurred in an unnamed tributary with a connected but discrete watershed.   The most probable cause of this kill was non-point source urban run-off.

·        The third largest occurred April 19th in an unnamed tributary of Croyden Creek in Rockville, Montgomery County.  Investigation revealed that 581 fish (2 species), 79 salamanders, and 1000 oligochaete worms died after a rain event.  The most probable cause of this kill was non-point source urban run-off.

·        The fourth largest occurred April 19th in an unnamed tributary of Booze Creek in Bethesda, Montgomery County.  Investigation revealed that 293 fish (1 species) died after a rain event.  The most probable cause of this kill was non-point source urban run-off.

·        The fifth largest occurred October 2nd in two private ponds in Grantsville, Garret County.  Investigation revealed that 140 fish (3 species) died after a small sewage spill entered the ponds.  The resulting BOD caused oxygen depletion killing the fish.

·        The sixth largest occurred April 19th in an unnamed tributary of the Upper Paint Branch in Colesville, Montgomery County.  Investigation revealed that 51 fish (1 species) and 500 oligochaete worms died after a rain event.  The most probable cause of this kill was non-point source urban run-off.

·        The seventh largest occurred August 1st in an an unnamed tributary of Cowpens Creek in Middle River, Baltimore County.  Investigation revealed that 25 fish (4 species) died as a result of a discharge of used cooking oil from a commercial business

 

2012 Pollution Caused Fish Kills

 

July 2002 fish kill in the Middle Patuxent River caused by a manure spill from a dairy farm (Photo: MDE)With pollution caused fish kills, the exact toxin or source is often not determined; especially if the report is received more than 24 hours after the event takes place. It is vitally important that fish kills be reported as quickly as possible in order to allow the best opportunity to find the cause and initiate corrective measures.

 

 

 

 

Contact Information

The Department asks that individuals who see an accumulation of dead fish in Waters of the State report it through the 24-hour, toll free Chesapeake Bay Safety and Environmental Hotline at 1-877-224-7229.

Maryland Department of the Environment
Science Services Administration
Fish Kill Investigation Section
416 Chinquapin Round Road
Annapolis, MD 21401

The annual fish kill summary report may be obtained by contacting Chris Luckett at 443-482-2731.

Other Links

Fish and Shellfish Program

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