Meadow Lake Snakehead Monitoring

Bureau of Fisheries Technical Brief #2017002

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Meadow Lake (94.9a) is the larger of two fresh water bodies located entirely within Flushing Meadows Corona Park in Queens County, NY. The two ponds are connected by a narrow creek, while Meadow Lake, the more downstream of the two, is connected to Flushing Bay through Flushing Creek. The connection is interrupted by a tide gate which is intermittently opened by managers at the NYC Parks Department. As a result, Meadow Lake has slightly elevated salinity that typically hovers in the range of 4-7ppt and hosts a mix of estuarine and freshwater fish species. Northern snakeheads were first found in the lake in 2005, and annual NYSDEC general biological boat electrofishing surveys have documented them at low levels of abundance since then. Boat electrofishing was conducted again in 2017 to continue monitoring the northern snakehead population and assess any impacts this introduced predator may have on the native fish community.

In 2017, one 18.7in adult northern snakehead was collected in Meadow Lake, out of 285 fish from 5 species (plus eels and carp that were observed but not collected). When compared to previous years, the northern snakehead population in Meadow Lake does not demonstrate a consistent trend either positive or negative (Figure 1). Only fall electrofishing surveys are compared across years since spring surveys were not conducted regularly and demonstrated dramatically reduced catch-rates.

Figure 1: Fall CPUE (number caught/h) for important fishes in Meadow Lake from 2011-2017. Since spring surveys have very different results only autumn surveys are included.

Consistent with past years, white perch were the most abundant fish collected (Table 1). 2017 also marked the third year in a row that not a single Lepomis spp. was captured in Meadow Lake. The beginning of the decline coincided with a large multi-species mortality event (cause unknown) that occurred during late summer/early fall in 2014. Also in 2014, the control board of Region 2's electrofishing boat was replaced. The new board limits the amount of voltage available for fishing. This limitation presents a disadvantage in high conductivity environments such as Meadow Lake and may also help explain why no further Lepomis have been captured. As of now there is no definitive explanation for the disappearance of sunfish from Meadow Lake surveys. Additional boat electrofishing as well as seine and trap net surveys will be conducted in 2018 to try and ascertain whether sunfish are truly absent or just difficult to catch.

Overall, there is no evidence that the snakehead population in Meadow Lake is increasing. There are also no evident impacts of snakeheads on native fish but the fish community of this system as revealed through electrofishing is not always consistent. Boat electrofishing surveys will continue annually to monitor the status of the snakehead population and its impacts.

Table 1: Percentage of individual fish by species in Meadow Lake from 2011 to 2017. Carp, eels, and snakeheads which were observed but not captured have been excluded.

	Survey Year
Species	2011	2012	2013	2014	2015	2016	2017
silverside	9.4	51.8	3.2	33.5	19.8	1.2	1.1
gizzard shad	3.4	1.5	2.8	20.7	1.5	4.3	20.0
brown bullhead	0.0	0.1	0.0	0.5	0.0	1.2	0.4
mummichog	0.0	0.5	0.3	0.3	1.7	5.5	0.0
white perch	68.2	39.5	81.9	44.6	72.5	83.5	74.4
pumpkinseed*	16.5	6.5	8.4	0.5	0.0	0.0	0.0
largemouth bass	0.4	0.0	0.0	0.0	0.0	0.0	0.0
snakehead	2.2	0.0	2.0	0.0	0.0	0.4	0.4
goldfish	0.0	0.0	0.0	0.0	3.5	0.8	2.8
other	0.0	0.0	0.0	0.0	0.2	3.1	0.0

https://www.dec.ny.gov/docs/fish_marine_pdf/snakeheadsnyc.pdf

Harlem Meer Centrarchid Survey

Bureau of Fisheries Technical Brief #2018013

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The Harlem Meer (the Meer) is a 10 acre lake in the Lower Hudson Watershed in the northeast corner of Central Park, New York County (Manhattan). Nearly 100% of its shoreline provides fishing access, and it is heavily used by local anglers (Cohen and Lee, 2017). As with other New York City (NYC) freshwater lakes and ponds, both New York State (NYS) and NYC angling regulations require catch and release of all fish. To monitor the status of the Meer's fish populations, spring boat electrofishing surveys have been performed bi-annually since 2009, with the exception of one performed during fall of 2011. This survey was performed on May 2, 2017 following the DEC Bureau of Fisheries Centrarchid Sampling Plan (Green 1989).

A total of 433 fish of seven species were captured; American eels and carp were not observed except for one grass carp at the surface prior to the survey. Catch rates for largemouth bass greater than eight (47 fish/hr), 12 (34.5 fish/hr) and 15 inches (14 fish/hr; Table 1.) in length were greater than 86%, 92% and 94%, respectively, of those from similarly-sized NYS lakes. The length frequency distribution (Figure 1) and size structure indicesi (PSD = 73, RSD15 = 29.7) were indicative of a primarily balanced population, with a high proportion of large largemouth bass. Average relative weight (88.5) indicates that largemouth bass were lean. Bluegill PSD was 25.2 and RSD15 was 0.3, both relatively low; however, the Meer has larger bluegills than other surveyed NYC lakes and ponds. The Harlem Meer has abundant largemouth bass and sunfish populations, and offers new and seasoned anglers potentially highly satisfying fishing opportunities.

Table 1. Number collected and length category catch rates for fish species captured during a boat electrofishing survey of the Harlem Meer in 2017.

				CPUE (fish/h; standard error)
Species	Total Catch	Time (h)	All sizes	Age-1	≥Stock	≥Quality	≥Preferred
Largemouth bass	45	0.8	57.7 (3)	10.3 (1)	47.4 (3)	34.6 (1)	14.1 (1)
Bluegill	370	0.8	474.4 (28)	61.5 (17)	413 (12)	104 (10)	1.3 (1)
Black crappie	12	0.8	15.4 (4)	0 (0)	16.7 (4)	11.5 (7)	6.4 (3)
Brown bullhead	2	0.8	2.6 (1)	0 (0)	2.6 (1)	2.6 (1)	2.6 (1)
Green sunfish	1	0.8	1.3 (1)	0 (0)	1.3 (1)	1.3 (1)	0 (0)
Pumpkinseed	1	0.8	4 (1)	4 (1)	0 (0)	0 (0)	0 (0)

ⁱ PSD (Proportional Stock Density) and RSD (Relative Stock Density) are indices that allow for standardized comparisons of size classes of fish and provide measures of fish population balance. PSD is the percent of the stock sized population that are quality size, and RSDp is the percent of the stock sized population that are preferred size. Populations of bass that are well-balanced (i.e., have good size distributions) have PSDs of 40-70 and RSDPs of 10-25.

Literature Cited

Van Cortlandt Lake Survey

Bureau of Fisheries Technical Brief #2017005

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Covering 18 acres, with 0.81 miles of shoreline, Van Cortlandt is the largest lake in the Bronx. It is a shallow lake (up to 8 ft deep) located in Van Cortlandt Park and is part of the Lower Hudson watershed. Much like all NYC waters, the shoreline is the only way to access the lake. The shoreline varies from flat grassy areas to steeper wooded spots, but all areas are accessible to anglers. The fishery is managed under catch and release only regulations, and barbless hooks must be used. Largemouth bass are the primary sportfish in the lake, and there are a variety of panfish such as yellow perch and sunfish. The lake was known for its quality yellow perch fishing in the past. In addition, the DEC I FISH NY program provides free clinics there to teach young students the joy of fishing and the importance of protecting our natural resources. A boat electrofishing survey following the DEC Centrarchid Sampling Manual was conducted in June 2017 to assess the status of sportfish and panfish populations.

A total of 145 fish consisting of nine different species were caught. Fifteen were largemouth bass ranging in size from five to a little over 18 inches. An assessment of condition indicated that largemouth bass were somewhat lean, which suggests that the population is over abundant or the forage base is not sufficient. The other species of fish caught included yellow perch, brown bullhead, golden shiner, goldfish, bluegill, pumpkinseed, black crappie and white sucker. Bluegill were the most common species, comprising 52% of the total catch; an increase from 21% from a previous survey conducted in 2013. Largemouth bass were 10% of the total 2017 catch, a decrease from 18% in 2013. There was a good number of quality sized brown bullhead, ranging up to 15 inches. There were also yellow perch and black crappie up to 12 inches. Eleven largemouth bass and 60 sunfish were collected and sent to the USFWS Lamar Fish Health Center for disease testing. Van Cortlandt Lake supports a diverse warmwater fish community that should provide quality fishing opportunities for largemouth bass and a variety of panfish. This survey confirms Van Cortlandt as a quintessential site for fisheries education and angler recreation.

Table 1. Number of fish collected and length category catch rates from Van Cortlandt Lake, 2017.

		Length category catch rate (number caught/hour)
Species	Number collected	0-4 in	4-6 in	6-8 in	8-10 in	10-12 in	12-15 in	15-18 in
Largemouth bass	14	0	4	0	1	1	11	1
Bluegill	76	4	57	47	0	0	0	0
Pumpkinseed	11	0	10	6	0	0	0	0
Brown bullhead	15	0	0	0	0	19	3	0
Yellow perch	8	0	1	3	6	1	0	0
Black crappie	7	0	0	3	6	1	0	0
White sucker	7	0	0	0	0	3	0	7
Golden shiner	6	0	0	3	6	0	0	0
Goldfish	1	0	0	0	0	1	0	0