Oct 052017
 

 Threats loom but fish populations in the Kawarthas are still doing well

One of my most formative nature experiences as a boy was fishing with my grandfather at the family cottage on Clear Lake. The excitement of hooking into a large bass or walleye was unforgettable. Even at that time, however, he always insisted that I throw the fish back – something I did with great reluctance at the time. His conservation ethic has stuck with me ever since.

The Kawarthas is home to world-class fisheries. In fact, our lakes are the most heavily fished inland lakes in Ontario. Today, the sport fish community is composed of muskellunge, smallmouth and largemouth bass, walleye (pickerel), yellow perch, bluegill, pumpkinseed and black crappie. While walleye populations have declined, most other populations are doing well.

For management purposes by the Ministry of Natural Resources and Forestry, the Kawartha Lakes, along with Lake Ontario creeks and rivers to the south, are located in Fishery Management Zone 17 (FMZ 17). Roughly speaking, FMZ 17 extends from Lake Ontario, north to Dalrymple Lake in the west and across to Belmont Lake in the east. The zone includes 64 lakes greater than five hectares. Rice Lake is the largest. All of the Kawartha Lakes have similar fish communities because of their similar habitat and their connectivity via the Trent-Severn Waterway.

Lakes in the northern Kawarthas (e.g., Anstruther, Jack, Chandos) are not considered part of the Kawartha Lakes and belong to a different management zone (FMZ 15). The fish community is similar, however, with the exception that some of the lakes are also home to coldwater species like lake trout.

All of the lakes in FMZ 17 are classified as “warmwater”. A number of major warmwater rivers also flow through the area. These include the Otonabee, Trent and Crowe Rivers. Coldwater streams are generally limited to the Oak Ridges Moraine, which runs parallel to Lake Ontario. These streams support fisheries for migratory rainbow trout and salmon from Lake Ontario, as well as resident populations of brook and brown trout. Surprisingly enough, Harper Creek in Peterborough is also a coldwater stream and provides habitat for an endangered population of brook trout. The lakes within FMZ 17 offer very little in terms of coldwater fish habitat.

Historically, the sport fish population of the Kawartha Lakes and the Crowe River watershed consisted primarily of muskellunge, smallmouth bass, pumpkinseed (sunfish) and yellow perch populations. However, starting in the 1920s, walleye were intentionally introduced into all of the lakes. Largemouth bass and rock bass then spread into the Kawartha Lakes and Crowe River watershed, followed by bluegill (another sunfish) and black crappie. The latter two are native to the Trent River system. Northern pike have become established, via range extensions and/or unintentional introductions to the periphery of the zone, including Canal Lake near Kirkfield and Belmont Lake north of Havelock.

Walleye: Following their initial introduction, the Kawartha Lakes supported abundant walleye populations, which soon became the dominant predatory fish. By the 1980s, however, the lakes had undergone a series of significant environmental changes that altered the composition and structure of the fish community. These included a rise in both water temperature and clarity and a decrease in phosphorus concentration. Phosphorus is a necessary nutrient for both plants and animals.

Increased water clarity from the spread of zebra mussels has reduced the competitive advantage that walleye possess over other species in more turbid (murky) water conditions. Zebra mussels filter plankton from the water column, hence the greater clarity. Their presence has also decreased nutrients like phosphorus available to lower levels of the food chain. This has likely decreased the overall productive capacity of the lakes and created more favourable conditions for species like bass and muskellunge and less favourable conditions for walleye. As water clears, the amount of habitat for the light sensitive walleye is reduced and predation on young walleye is likely to increase. In lakes where bass are thriving, walleye tend to do more poorly. This is mainly because bass prey on young walleye.

Walleye decline continued through the 1990s, which was a decade that saw increases in new species such as black crappie and bluegill. Fewer large walleye in the lakes and rivers also means reduced predation of other species such as yellow perch, which feed on juvenile walleye.

Bass:  Overall, populations of smallmouth and largemouth bass in the Kawartha Lakes are considered healthy. The trends in their abundance are best explained by the ecology of each species and the habitat present in each lake. Some lakes, such as Rice and Pigeon Lakes, provide diverse habitat and are able to support abundant populations of both species. Other lakes, such as Balsam Lake, offer limited habitat for largemouth bass but do support abundant smallmouth bass populations. At the other end of the spectrum, lakes such as Chemong and Scugog provide a greater amount of shallow, vegetated largemouth bass habitat while smallmouth bass habitat is less abundant. Changes in water clarity, temperature and shifts in the predator community have also increased bass production. Climate change modeling predicts a dramatic increase in warmwater fish species, including bass.

Yellow perch:  Yellow perch populations are healthy and show successful and consistent reproduction. This species provides a critical prey base for a number of species, including walleye.

Sunfish and crappie: The abundance and distribution of bluegill, pumpkinseed and black crappie populations are best explained collectively, since these species are closely related and interact a great deal. Bluegills and crappie both compete with native pumpkinseed. The latter has undergone a gradual decline in abundance since bluegill and black crappie arrived and exploded in number. Now, bluegill abundance appears to have stabilized, but black crappie may still be increasing. Bluegill and crappie are now thriving in the northern Kawarthas, as well.

Pike and muskie:  FMZ 17 supports a healthy, high quality muskellunge fishery. This is likely attributable to the combination of suitable habitat and the absence of northern pike. Pike and muskellunge compete for both habitat and food resources, and muskellunge density is typically lower when pike are present. Northern pike are currently not present in the majority of waters in FMZ 17. However, as already noted, they are present around the periphery of the zone and moving downstream from the west. Pike have typically been managed as an invasive species due to concerns for muskellunge populations and disruption of lake ecosystems. While muskie populations are currently healthy, the potential invasion of northern pike to the Kawartha Lakes remains a serious threat.

Brook trout: Brook trout (speckled trout) are the only self-sustaining, naturally reproducing native salmonid (salmon, char and trout) species in FMZ 17. They are synonymous with high quality environments. However, they are now mostly limited to isolated, often low density, populations in streams on the Oak Ridges Moraine. These include Baxter Creek near Millbrook and Fleetwood Creek near Bethany. Their low abundance is explained mostly by habitat degradation and competition with brown and rainbow trout, both of which prey on juvenile brook trout. Brookies have experienced considerable losses across their native range in eastern North America.

Sustained by cold groundwater, Harper Creek in the south-west end of Peterborough is home to one of the few remaining wild brook trout populations in Southern Ontario. A research team recently tagged 20 of these trout and will be able to follow their daily and seasonal movements. This will provide a window into the life history of wild brook trout in an urbanized and severely threatened watershed.

Lake trout: Northern Peterborough County still boasts healthy lake trout populations. In Jack Lake, for example, a naturally reproducing population is present in Sharpe’s Bay. Water quality here is excellent, with oxygen present right to the bottom.  Deepwater sculpin provide much of the food base for these fish. Historically, Stony Lake also had a population of lake trout, but they are believed to have disappeared the late 1980s.

Brown trout:   Brown trout were stocked between 1920 and 1975 in many streams in order to diversify fishing opportunities. They are a resident fish, which means they complete their entire life cycle in the same stream. Like brook trout, they spawn in the fall. Brown trout out-compete their native cousins, particularly when rainbow trout are also present. Their competitive advantage is due to greater temperature range tolerance, more spawning flexibility and larger body size.

Rainbow trout:  The stocking of rainbow trout also began in the 1920s. Not only are the populations healthy and self-sustaining, but they are now the most dominant salmonid in most Lake Ontario tributaries. Since 1974, the spring rainbow trout run has been monitored at the Ganaraska fishway at Corbett’s Dam in Port Hope. The construction of the fishway in the 1970s provided access to upstream spawning and nursery habitat.

Atlantic salmon: Starting in the 1980s and 90s, Atlantic salmon were experimentally stocked in eight Lake Ontario streams, including Wilmot Creek and the Ganaraska River. The Ganaraska offers excellent juvenile habitat for Atlantic salmon. Once a dominant Lake Ontario species, they were extirpated by the late 1800s.

Chinook and coho:  Native to the Pacific coast, Chinook and coho salmon were stocked in Lake Ontario in the late 1960s to provide recreational angling opportunities and to establish a top predator salmonid species following the dramatic decline in lake trout abundance in the lake. The populations are now reproducing naturally. Every year in September, they can be observed jumping up the fish ladder at Corbett’s Dam in Port Hope as they move upstream to spawn. It’s quite a spectacle!

Next week, I’ll turn my attention to non-game and endangered species. I’ll also look at the many challenges that fish populations are facing in the Kawarthas.

May 192017
 

Jacob Bowman, a 15 year old Peterborough high school student, is in Regina, Saskatchewan this week at the Canada Wide Science Fair (CWSF), presenting his research on the brook trout in Harper Creek. He qualified for the trip by winning the Peterborough Regional Science Fair last month.

Jacob’s project is called “Fish or chips? Brook trout in Harper Creek”. He has shown that the northern tributary of the creek, which runs along Rye St., has the highest quality trout habitat in the Harper Creek system. This is also the section that will be most affected by expansion of Rye St. The photo below shows Jacob’s CWSF presentation materials, including: a 5-page report on his research, his display poster, and a photograph of the material on display in Regina.

CONCLUSIONS OF JACOB’S RESEARCH

North Harper Creek had all of the components necessary for brook trout residence. It had the most stable temperature range of the sampled sections. Different food sources for fish were recorded. Brook trout were regularly observed in the creek and more fish were seen there than in any other section. Some of the other sections of the creek system exceeded the thermal tolerance level for brook trout (20°C). North Harper Creek’s temperature remained well within the tolerance level year round. Years ago the creek was altered to fit the growing developments in the area. During this process a steep grade that may impede fish passage was created at the mouth of North Harper Creek. Trout in the creek appear to be disconnected from the other sections of the creek system. North Harper Creek contains a small relic population of native brook trout that are at risk from development including the Rye St. expansion. If Rye St. expansion is to proceed, brook trout in North Harper Creek may be at risk without proper management. A plan will have to be devised to accommodate the trout. An underground stream running through culverts is not survivable for brook trout (Georig et al. 2016). They would have to move to other more suitable habitat or die. A better option would be to leave the creek were it is and begin some habitat enhancement, such as tree planting. If the creek must be moved, it is critical that it intercepts groundwater sources, since brook trout require groundwater for reproduction (Meisner 1990). It is very important that this last southern Ontario stronghold of brook trout be preserved for future generations and becomes an example of good stream conservation.”

via Jeff Bowman

Jacob Bowman sampling invertebrates in Harper Creek in January, 2016 – Jeff Bowman photo

Display of Jacob Bowman’s Brook Trout research – May 2017 – Jeff Bowman photo

Apr 062017
 

When I used to hear the words ‘brook trout’, the image that came to mind was a pristine lake in Algonquin Park. Well, that image has changed. What I now see is a tiny stream running along Rye Street in this busy commercial and industrial sector of southwest Peterborough. As surprising as it may sound, this branch of Harper Creek is an urban coldwater stream and home to a native brook trout population – an ecological gem that no other urban area in the entire province can claim. And, if wasn’t for the work of a 15-year-old boy, we would know far less about these fish.

A female Brook Trout on her redd in Harper Creek – Don McLeod

Harper Creek originates in Stenson Park, which is located just north of Stenson Boulevard. One branch of the creek can be seen flowing adjacent to the CPR rail-line on the east side of Harper Road. Another flows through the ditch along the north side of Rye Street. Both are cold water streams which eventually discharge into Byersville Creek and on into the Otonabee River.

The south tributaries flow through Harper Park, a 60 hectare (150 acre), municipally-owned, protected natural area. Roughly speaking, the Park is bordered by Westview Village condominiums and Holy Cross high school to the north, Harper Road to the east, Ramblewood Drive to the west and Fleming Drive to the south. Much of the park, as well as parts of the surrounding area, form a wetland which was recently designated as Provincially Significant. These wet meadows, forested swamp and marsh provide habitat to many locally-unique species of native plants and animals. The wetland is particularly significant because it contains numerous areas of groundwater seepage and coldwater springs which flow into Harper Creek. The bad news, however, is that Harper Park and the creek itself are under threat from multiple developments in the area, including the OLG casino and associated road development.

Bowman Study

The Harper Creek brook trout population is entirely wild; in other words, it is free from interbreeding with hatchery fish. This alone is a rarity. It is believed that the very substantial groundwater flow and coldwater springs have allowed the fish to persist in the creek despite channelization of some sections (e.g., along Rye Street), industrial development, storm sewer outflows and the dumping of fill into the stream bed.

Up until recently, this population was never systematically studied. We don’t know, for example, how it has reacted to the many pressures listed above. Now, new developments along the stream such as the casino are likely to create additional stressors such as increased water turbidity (e.g., suspended solids like silt), increased artificial lighting and periods of more salt in the water from winter road maintenance.

In the last three years, however, our knowledge of the Harper Park brook trout has increased a great deal, thanks largely to the work of 14-year-old Jacob Bowman. Jacob has had a personal interest in brook trout all his life. In 2014, when he was just 12, Jacob started studying the Harper Creek trout as a Peterborough Regional Science Fair project. In addition to making regular observations of the fish themselves, he sampled water temperature, water depth and the presence of invertebrates at various locations throughout the Harper Creek system. He found that the northern branch along Rye Street had the narrowest annual range of water temperature (9.5°C) and was both the coldest section in summer and the warmest in winter. Harper Creek, within the boundary of Harper Park, had the second narrowest temperature range (12.5°C), ranging from 3.5°C in winter to 16°C in summer. All other sections of the creek system had a far greater range. For example, during the extreme heat of July 2016, these sections reached temperatures of 20°C, which is close to the maximum temperature trout can cope with. At the same time, however, the northern branch was only 15°C. This was the coldest of all sites measured, and trout were observed here over the entire course of the study. Other sections of the creek system have less stable water temperatures and levels, which have led to highly variable occupancy by trout.

Jacob Bowman sampling invertebrates in Harper Creek in January, 2016. The local teen has been studying the ecology of Harper Creek since he was 12. (Photo by Jeff Bowman)

As Jacob has demonstrated, brook trout are highly sensitive to water temperature, especially when it comes to spawning and egg incubation. The fish spawn any time from October to late November and usually choose shallow, gravel bottom sites, where spring water keeps the eggs well-oxygenated and relatively warm during winter. Prior to hatching, the eggs will need two to three months of development. They emerge from the eggs in February to March, but an egg sac is still attached. In this “alevin” stay, the fish remain in the protective gravel of the redd (nest), and all of their nutritional needs are provided by the egg sac. The sac slowly shrinks and the “fry” start swimming up from the bottom in March or April.

Water from natural springs is warmed by geothermal heat from the earth. This will keep spring-fed creeks at water temperatures of between 5 and 10C, in contrast to surface water creeks which often see temperatures in winter drop to 0 C. Without this warming effect, successful egg development in brook trout is not possible.

From a water temperature perspective, the northern branch is the highest quality trout habitat that Jacob assessed in the Harper Creek system. Trout in this branch are buffered from the heat of summer and the cold of winter. This allows them to save energy and enjoy enhanced survival compared to other sections of the creek.

New study  

Jacob’s work has proven to be the catalyst for more research. The Peterborough Field Naturalists and the Ontario Federation of Anglers and Hunters are now partnering with Trent University to conduct a new, two-year comprehensive study of Harper Creek brook trout. The study will use a technique known as fish telemetry, in which acoustic tags are implanted in the fish. The tags are small, sound-emitting devices that allow the detection and/or remote tracking of fish in three dimensions. The study will begin this spring with the tagging of 20 brook trout Each trout will carry a radio tag weighing less than one gram, which minimizes impacts on the fish’s behaviour. Harper Creek brook trout are quite small, averaging only 7 inches – too small for anglers to keep. The research will be conducted by Scott Blair, a Trent graduate student.

The study will track the brook trout’s seasonal movements and habitat use. Parameters such as water temperature, salinity, turbidity, prey availability and the abundance of other fish species will also be monitored. All of this information will be used to create a habitat model as well as identifying how human impacts are, and will be, affecting the fish. Like Jacob Bowman’s study, the researchers will be able to identify the most valuable brook trout habitat, project the potential impact of planned developments in the area and inform mitigation measures to protect this valuable population.

You or your organization can collaborate in this research, too, thanks to a program called “Fund and Follow a Fish”. Two options are available. You can fund an individual fish by covering the cost of its $200, hand-made tag, or you can simply make a donation in any amount to the research effort in general. By covering the cost of a tag, you will be connected directly to an individual brook trout. You will receive a picture of your fish; information about its gender, length, weight and unique traits; data about where and when it moves within Harper Creek; and a copy of the entire study when published. A picture of you and your trout – you can give it a name! – will be posted on the Harper Park website. Most importantly, you will have the satisfaction of knowing that your funding will help researchers reveal the hidden life history of the beautiful ‘brookies’ in Harper Creek. At a time when approximately 80% of the brook trout populations in Southern Ontario have disappeared, you will be helping the Trent University team gather information that could help conserve brook trout in other communities. Go to peterboroughnature.org/harper-park/trout-study/ for detailed instructions on how to make your donation.

Recommendations

The Harper Creek system is small, isolated and fragmented. It is often difficult for the various sub-populations of the fish to move from one section of the Creek to another. Harming any of the trout populations – and especially ones of high quality such as along Rye Street – will reduce the overall population size and increase the risk of all Harper Creek brook trout disappearing.

A section of Harper Creek runs in a ditch along the north side of Rye Street in Peterborough (photo: Drew Monkman)

 

Like many people in Peterborough, Jacob is concerned about the anticipated impacts from the proposed casino development and the Harper Road realignment. Any development in the area needs to maintain or enhance the connectedness of creeks in the system as well as the overall amount of cold water (including groundwater) habitat accessible to the trout.

One option may be to leave the northern branch where it is, and to plant native trees and vegetation along the edge to further protect the creek from disturbance. Failing this, it may be possible to redirect the stream to within the protected natural area. Success, however, will depend primarily on intercepting groundwater sources. Failure to do so will lead to the loss of this trout population and possibly all of the Harper Creek brook trout. And, if you’re wondering about Jacob’s science fair project, he ended up winning in his category and bought himself some fishing equipment. You won’t find him fishing in Harper Creek, however!

To see more pictures of Harper Park fish and wildlife, go to donaldmcleod.com/Stories