Written by Mike Smith

Bringing Migratory Fish Back to Sligo

In the past, the waters of lower Sligo Creek reportedly were filled with herring in the spring. I ran into a guy who lives now lives in St. Mary's County who said he grew up in the Sligo Creek watershed, in the downstream section (my guess is near the current Green Meadows Park near Ager Road) . He remembered around 1966 people used to go to Sligo Creek with buckets and easily fill them with herring swimming upstream. Over time, fish barriers made it impossible for the herring to reach Sligo Creek to spawn.

But migratory fish may soon be returning to Sligo's waters, as a result of improvements made to the lower portion of the Creek's physical structure in 2003 and 2004.

Fish such as alewife herring, white perch, and blueback herring have already been found in Northwest Branch, near the confluence with Sligo, as a result of similar improvements.

The Maryland National Capital Park and Planning Commission (M-NCPPC) removed fish barriers from four sites along the Sligo between Riggs Road and the confluence with Northwest Branch. This work was done as part of the Wilson Bridge Project Environmental Initiatives, mandated to compensate for damage to habitat near the bridge construction site.

With the barriers removed in lower Sligo and Northwest Branch, migratory fish should be able to enter Sligo Creek to spawn at the four sites.

The Woodrow Wilson Bridge Project web pages provide a slide showing of the changes made to Northwest Branch and Sligo Creek at www.wilsonbridge.com/ea-MitNorthwest.htm. The Sligo Creek slides start at slide 18.

The Sligo Creek Fish Passage Improvements page describes the 2003-2004 removal of fish barriers that were obstacles that would prevent migratory fish from entering Sligo Creek.

The Northwest Branch is now being monitored each spring to see how far the migratory fish go up each year. It is expected over time they will edge closer to Sligo Creek.

2008 Ichthyoplankton Monitoring1

The ichthyoplankton sampling occurred two to three times per week during the sampling season. The sampling effort was initiated after a large amount of herring were visually observed and collected through electroshocking methods in March. Sampling continued until the third week of May to ensure that later spawning species were observed. Electroshocking methods were employed to determine the presence or absence of each of the target species throughout the sampling season. It was found this migratory season that large numbers of White Perch were still present beyond their normal stay in the system. Conversely, there were species such as the blueback herring that had a weak presence during this migratory season. This summarizes the results of the ichthyoplankton surveys in Northwest Branch in 2008.

Site Date Species Collected Form
NW-3 (near USGS station at Queens Chapel Road) 5/07/2008 River herring Eggs
NW-3 (near USGS station at Queens Chapel Road) 5/07/2008 Resident cyprinid Eggs


River herring eggs were collected on one occasion during the 2008 sampling season. These herring eggs were collected just downstream of the NW-3 RGC, which matched the farthest point upstream that eggs were collected in 2007. Generally, anecdotal evidence from resource managers throughout the state indicated that the Potomac River watershed herring run was weak. Electrofishing surveys conducted within Northwest Branch showed less than average migratory fish populations. Factors that may have negatively influenced fish migration in the Anacostia watershed include: the cleanup of submerged rail road cars in the Anacostia River which required the use of turbidity curtains; and a temporary piping system needed by Washington Suburban Sanitary 20 Commission (WSSC) as a bypass for a broken sewer main located in lower Northwest Branch.

Fish passage monitoring for 2009 will continue to utilize ichthyoplankton sampling, with particular focus on the sites located upstream of NW-3.


2007 Ichthyoplankton Monitoring2

Herring eggs were collected within the bottom of the NW-3 RGC structure on April 23, 2007. This is the furthest upstream migration that has been documented in Northwest Branch in recent history. Alewife herring were first observed within Northwest Branch in mid-March and visual and electroshocking surveys confirmed their presence until March 31st. Blueback herring were not observed within the system until late April and were note collected until mid-May. These surveys at NW-0 indicated that the alewife herring run, earlier in the spring was stronger than the blueback herring run that began in early May. These surveys also indicated a very weak white perch run within the Northwest Branch system, compared to numbers seen in past years. Communication with MDNR personnel provided anectdoctal evidence of an overall weak white perch run throughout the state.

Fish passage monitoring for 2007 will continue to use ichthyoplankton sampling, with particular focus on the sites upstream of NW-3.

Site Date Species Collected Form
NW-0 (Route 1) 3/27/07 River herring Eggs
NW-3 (near USGS station at Queens Chapel Road) 4/13/07 White sucker Eggs
Below 38th Street 4/23/07 River herring Eggs
NW-2 (near footbridge downstream of Queens Chapel Road) 4/23/07 River herring Eggs
NW-3 (near USGS station at Queens Chapel Road) 4/23/07 River herring
White sucker		 Eggs
NW-6 (just downstream of Sligo Creek confluence) 5/1/07 Resident cyprinid Eggs and Larvae
NW-8 (Northwest Branch and East-West Highway) 5/1/07 White sucker
Common carp 		Larvae
Eggs
NW-4 (near West Hyattsville Metro station) 5/8/07 White sucker Larvae
NW-6 (just downstream of Sligo Creek confluence) 5/8/07 White sucker Larvae
NW-6 (just downstream of Sligo Creek confluence) 5/10/07 Resident cyprinid Eggs
NW-8 (Northwest Branch and East-West Highway) 5/15/07 Resident cyprinid Eggs
NW-8 (Northwest Branch and East-West Highway) 5/16/07 Resident cyprinid Larvae

2006 Monitoring3

A very dry spring with cold temperatures may have resulted in a weak herring run in 2006.

Site Date Method Target Species Number
NW Branch below Route 1 bridge 3/13/06 electrofishing Alewife Herring 1
3/29/06 visual Alewife Herring N/A
3/31/06 electrofishing Alewife Herring 3
4/09/06 visual None N/A
4/13/06 electrofishing/haul seine None N/A
4/21/06 electrofishing Yellow Perch 1
4/27/06 electrofishing Yellow Perch 1
4/28/06 electrofishing/haul seine Yellow Perch
White Perch
Blueback Herring		 3
1
5
5/3/06 electrofishing/haul seine Blueback Herring (dead) 1
5/13/06 haul seine White Perch
Yellow Perch
Blueback Herring		 67
1
1

2005 Monitoring4

Site Date Method Target Species Number
NW Branch below Route 1 bridge 3/31/05 electrofishing none N/A
4/05/05 electrofishing/seine Alewife Herring 37
5/03/05 electrofishing None N/A
5/09/05 electrofishing White Perch 1
5/10/05 visual None N/A
5/11/05 visual Blueback Herring >50
5/12/05 electrofishing Alewife Herring
White Perch		 1
4
5/13/05 visual Alewife Herring N/A
5/14/05 electrofishing White Perch 1
NW Branch above Route 1 bridge 4/11/05 fish trap Alewife Herring 1
4/12/05 fish trap None N/A
4/19/05 fish trap Alewife Herring 2
NW Branch below 38th Street bridge 3/31/05 electrofishing None N/A
4/05/05 electrofishing None N/A
5/03/05 visual None N/A
NW Branch at 38th Street bridge
riffle-grade control structure		 4/05/05 electrofishing None N/A
5/03/05 visual None N/A
NW Branch at footbridge
upstream of 38th Street bridge		 4/26/05 fish trap None N/A
5/03/05 -
5/06/05		 fish trap None N/A
5/09/05 -
5/10/05		 fish trap None N/A
5/11/05 visual Blueback Herring 7
NW Branch near West Hyattsville Metro Station 5/11/05 -
5/14/05		 fish trap None N/A

2004 Monitoring5

Site Date Target Species Number
NW Branch-1 (38th Street) 3/19/04 None N/A
3/25/04 None N/A
3/29/04 Alewife Herring 2
4/07/04 None N/A
4/15/04 None N/A
NW Branch-1 at Pump House 3/27/04 None N/A
4/15/04 None N/A
4/28/04 None N/A
NW Branch-3 at Queens Chapel Road 4/22/04 None N/A
4/28/04 None N/A
4/29/04 None N/A
5/04/04 None N/A
NW Branch-6 at footbridge 4/05/04 None N/A
4/22/04 None N/A
5/04/04 None N/A

Sources:

1"Fish Passage Restoration: Post Construction Mitigation Monitoring Report (Year 5): July 2008, Contract Number PG3445173, Northwest Branch and Sligo Creek" from Maryland State Highway Administration and Potomac Crossing Consultants; from pdf version

2"Fish Passage Restoration: Post Construction Mitigation Monitoring Report (Year 4 of 5): August 2007, Contract Number PG3445173, Northwest Branch and Sligo Creek" from Maryland State Highway Administration and Potomac Crossing Consultants

3"Fish Passage Restoration: Post Construction Mitigation Monitoring Report (Year 3 of 5): August 2006, Contract Number PG3445173, Northwest Branch and Sligo Creek" from Maryland State Highway Administration and Potomac Crossing Consultants

4"Fish Passage Restoration: Post Construction Mitigation Monitoring Report (Year 2 of 5): June 2005, Contract Number PG3445173, Northwest Branch and Sligo Creek" from Maryland State Highway Administration and Potomac Crossing Consultants

5"Fish Passage Restoration: Post Construction Mitigation Monitoring Report (Year 1 of 5): 2004, Contract Number PG3445173, Northwest Branch and Sligo Creek" from Maryland State Highway Administration and Potomac Crossing Consultants; from pdf version