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This progress report describes recent findings of the County's comprehensive fish community monitoring program (July 2007).

Each year, the Onondaga County Department of Water Environment Protection (WEP) monitors Onondaga Lake to measure how the lake is changing as pollution levels decline. The 2006 WEP Ambient Monitoring Program (AMP) represents the thirty-seventh consecutive year of Onondaga County's lake monitoring effort. The County monitoring program measures physical, chemical, and biological conditions and compares the results to state and federal standards. By law, all waters are to support recreational use and a balanced biological community. This national requirement is often referred to as ensuring that all waters are "fishable and swimmable."
 

Measures of progress

The County's biological monitoring program tracks a number of plant and animal communities in the lake ecosystem. The monitoring program measures the number and types of fish, aquatic plants, macroinvertebrates, phytoplankton (algae), zooplankton, and zebra mussels. Results of the biological monitoring program are very encouraging; the lake now supports a diverse and productive biological community. Fish are quite abundant, and angling is becoming increasingly popular. Onondaga Lake is beginning to resemble other lakes of its size in the area with respect to the number of fish species, plant abundance, and summertime water clarity.

Q: How many and what kinds of fish are in Onondaga Lake?
A: Popular belief is that Onondaga Lake's legacy of pollution has left the lake a biological wasteland. This couldn't be further from the truth. In fact, the County's monitoring program has captured forty-four different fish species since 2000. When combining the County species list with that of other recent studies, sixty-four fish species have been identified in the lake in recent years. See table.
 

One reason for this abundance of fish is the interconnections between Onondaga Lake and other regional waterways. Onondaga Lake is an open system, meaning that it is connected to other streams, rivers, and lakes with no barriers to fish passage. Ninemile Creek connects Otisco Lake to Onondaga Lake. The lake outlet flows north into the Seneca River. Many fish likely enter the lake from the river and tributaries. For example, lake sturgeon stocked in Oneida Lake have made their way to Onondaga Lake through the river system. Tiger musky stocked in Otisco Lake and brown trout stocked in streams connected to Onondaga Lake have swum downstream and been caught in Onondaga Lake.

Q: Are the fish safe to eat?
A: Because of a history of mercury pollution, fish in Onondaga Lake have had elevated levels of mercury for many years. The NYS Department of Health has issued a health advisory to eat no more than one meal per month of any species caught in Onondaga Lake, to eat no largemouth or smallmouth bass over 15 inches, and to eat no walleye of any size.

Q: What kind of fishery does the Lake currently support?
A: Onondaga Lake currently supports a very productive warm water fishery. Anglers, both recreational and professional, from across the region enjoy the lake's excellent largemouth and smallmouth bass fishing. Numerous bass tournaments are held on the lake every year.

In July 2007, Onondaga Lake was the venue to a major Bass Anglers Sportsman's Society (BASS) bass fishing tournament that received national coverage on ESPN. Shore anglers catch combinations of bass, sunfish, white perch, carp, bullhead, and catfish.

The lake also supports some popular cool water species such as walleye and yellow perch, but they tend not to be as abundant as the warm water species.

Some cold water species, such as brown trout, are also caught during the colder part of the year.

Figure 1. Angler catch rates of largemouth bass

Q: Has fishing success improved?
A: WEP surveys anglers fishing on Onondaga Lake, the Seneca River, and Oneida River through the use of an Angler Diary Program. The diaries monitor angler catch rates for all species, but focus on the popular bass fishery. The catch rates in Onondaga Lake and the river system have been variable (Figure 1). Fishing success in Onondaga Lake is typically comparable to, or slightly better than, fishing success in other regional waters, including Oneida Lake.

The summer of 2006 was particularly good for Onondaga Lake anglers, with a catch rate of about one bass per hour—almost double the rate reported by Seneca River anglers. The most notable change evident from the diary program has been the dramatic increase in angler catch rates in the Oneida River. This increase probably reflects natural variability in fish populations and angler catch rates—not effects of the lake clean-up program.

Q: If I catch a fish with a tag, what should I do?
A: As part of its ongoing monitoring, WEP tags fish in Onondaga Lake with a yellow "spaghetti tag" below the dorsal fin (fin on the fish's back). The information gathered from these tags, such as how far the fish moved and how much it has grown since it was tagged, is important in helping managers understand the fish community. So far, it is clear that growth rates of the Onondaga Lake fish community are comparable to, or even higher than, growth rates seen in other New York lakes. Also, few fish migrate far from the lake.

Anyone catching a tagged fish should record the tag number, the length, weight, and location caught, and report this information to WEP (315-435-2260 x360).

Figure 2. Increase in area of Onondaga Lake covered by aquatic plants since 2000 (no data for 2004)

Q: I've noticed a lot of aquatic plant growth in the Lake lately. Is this good for the Lake?
A: You're right. The amount of aquatic plants in the lake has increased dramatically in recent years. Aquatic plants are greatly expanding as water quality improves, although there is natural variability from year to year as is common in regional lakes (Figure 2).

As long as plant growth doesn't get out of control, this is a very good thing for the lake. Aquatic plants act as essential rearing and nursery habitat for fish; they help to stabilize the bottom and also help clear the water. If the wrong kinds of plants get into the lake, and they become abundant enough, they can pose problems for lake users. Of particular concern are invasive species such as water chestnut and Eurasian watermilfoil. For this reason, WEP is closely monitoring the plant community.

Figure 3. Annual catch rate of adult largemouth bass

Q: With all the recent upgrades to the Metro wastewater treatment plant (located on the southern shore of the lake) has the fish community shown an improvement?
A: Yes, the fish community is improving and more quickly than anticipated. The overall number of fish species caught in the lake has increased since comprehensive monitoring began in 2000. The abundance of many types of fish is increasing, including important game fish species such as largemouth bass (Figure 3).

Reproduction, although naturally variable, has also seen some significant improvements (Figure 4). The increase in bass reproduction appears to be correlated with the increased abundance of aquatic plants, which provide cover and nursery areas. These positive trends are expected to continue.

Figure 4. Annual catch rates of juvenile largemouth bass

Q: What can we expect in the future?
A: Water and habitat quality will continue to improve in Onondaga Lake as the lake clean-up project moves forward. In response, the biological community and fishery should also improve.

There are, however, many uncertainties. Biological communities can be affected by factors other than simply the quality of the water:

• Several fish diseases, including largemouth bass virus (LMBV), and viral hemorrhagic septicemia (VHS), have been recently discovered in nearby fish populations. (These diseases are not transmittable to humans.)
• Invasive species also continue to be a serious problem in regional waterways. For example, the round goby, which is already present in Lake Ontario, has the potential to dramatically alter the lake's food web.
• Natural population variability, unrelated to remediation efforts, can cause unpredictable changes.

These issues are not limited to Onondaga Lake; all regional lakes face these challenges. Despite these issues, it appears that Onondaga Lake and its fish community will continue to improve.
 

 

Angler diary program
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Tagged fish
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Fish larvae
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Fish nests in Onondaga Lake
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Counting zebra mussels
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For additional information on fish in Onondaga Lake, please contact Dave Snyder, 315-435-2260.