Walleye population trends and status of the fishery

Walleye populations across southern Ontario were surveyed using the Fall Walleye Index Netting survey (FWIN) methodology between 1996 and 2009. There were a total of 40 FWIN surveys conducted on 34 lakes in FMZ 18. In addition, BsM surveys were conducted on 23 lakes in FMZ 18 from 2008 – 2010. The results of these two survey methodologies will be presented separately as they cannot be directly compared.

Walleye abundance is impacted by harvest and quality of habitat and is estimated by the average number of walleye per net (catch rate or catch per unit effort (CUE)). The mean walleye catch rate from the FWIN surveys is 3.0 walleye per net in FMZ 18, compared to 3.6 walleye/net for FMZ 17 (adjacent to FMZ 18), 7.9 walleye/net for FMZ 5, and 15.8 walleye/net for FMZ 4 (FMZ 4 and 5 are in Northwestern Ontario). The lower abundance of walleye in southern Ontario can likely be attributed to the higher number of stressors walleye are generally exposed to relative to northern Ontario. The prevalence of shoreline alteration, industrial and agricultural contaminations, fish community complexity and invasive species introductions tends to be higher in the south. In addition, 60% of the angling effort is expended in southern Ontario where the population is most concentrated (OMNR, 2009a). The most intense effort was observed in FMZ 17 and FMZ 18.

The mean catch rate from the BsM surveys is 0.8 walleye per net. A greater number of age classes and high maximum age are indicative of successful recruitment and adult survival. The assessment data show that few walleye are reaching the maximum age of 10-12 years (Scott & Crossman, 1998) suggesting weak survival. Only 4% (BsM) and 7% (FWIN) of the walleye were 10 years or older.

Recent studies suggest that large, older females play a vital role in facilitating population growth in walleye. Older females tend to produce larger eggs which in turn produce juveniles with higher survival rates (Venturelli et al., 2010). Fisheries management strategies should act to protect large females in populations that are at low abundances. The majority of lakes in FMZ 18 assessed by BsM and FWIN surveys had a high proportion of fish at or near the age of sexual maturity although survival past the age of maturity appears low.

The introduction of zebra mussels into many of the walleye lakes in FMZ 18 has increased the water clarity and reduced the amount of habitat suitable for walleye. The increased water clarity reduces the walleye’s competitive advantage as a predator in turbid waters. The young walleye also become more vulnerable to predation especially with the arrival of non-native species such as back crappie. These factors will limit the productive capacity of walleye and must be considered when assessing the effectiveness of management actions.

In summary, walleye populations in FMZ 18 are currently considered to be at relatively low abundance and are showing signs of high mortality. Most populations have high proportions of fish at or near maturity, but lack large, older (primarily female) fish. The management focus for this species is to try and increase population abundance beyond current levels, recognizing that not all walleye fisheries will increase in abundance, due to changes in fish community composition and unsuitable habitat conditions.

Sauger population trends and status of the fishery

A very limited number of sauger fisheries exist in FMZ 18. Only one of them was surveyed using the FWIN methodology in 2001. In summary, sauger fisheries in FMZ 18 require more assessment. The management focus for this species is to determine the status of the fishery, and its distribution within the zone.

Walleye and sauger management in FMZ 18

The current combined walleye and sauger size limit regulations as it applies to sauger has also been recognized as a concern and a priority in the fisheries management plan, as harvest of this desirable sport fish species is mostly limited by the current size restrictions (sauger maximum total length < 400 mm – from limited FMZ 18 data, including a number of fish at the maximum age of 5 – 6 years (Scott & Crossman, 1998)).

The decline in walleye abundance in FMZ 18 has been recognized as a concern and a high priority in the fisheries management plan. The lack of assessment data for sauger in FMZ 18 has been recognized as a concern and a priority in the fisheries management plan.

MNRF and the Advisory Council identified a number of challenges to managing walleye and sauger populations in FMZ 18.

Management challenges

  • Decreased adult walleye abundance.
  • Sustained high level of fishing effort for walleye (and indirectly for sauger).
  • Harvest demand is exceeding the current supply of walleye.
  • Complex fish communities dominated by predator/competitor species that feed on juvenile walleye and climate change are reducing reproductive potential of walleye populations.
  • Physical changes to the lakes that have made them less suitable to walleye.
  • Water level and flow fluctuations in the spring causing recruitment failure.
  • Lack of assessment data for sauger.

The MNRF with the advice of the Advisory Council developed objectives and strategies to address the challenges and help reach the following walleye and sauger management goals.

Walleye goal:

To increase walleye populations and improve walleye angling and harvesting opportunities.

Sauger goal:

To maintain or possibly increase sauger populations, and improve sauger harvesting opportunities.

Objective 1:

Increase walleye (and determine sauger) abundance and the number of sustainable populations.

As described earlier in this section, the walleye population abundance in FMZ 18 is low. MNRF and the Advisory Council agreed that walleye populations in FMZ 18 have declined in recent years. Harvest is one of the main threats to walleye populations since this is a very desirable species for anglers to harvest. The most effective management tool to overcome these challenges is to implement more effective harvest regulations, such as the harvestable slot size regulation implemented in 2013.

The sauger population abundance in FMZ 18 is unknown. MNRF and the Advisory Council agreed that harvest opportunities for sauger populations in FMZ 18 are extremely limited under the existing combined walleye and sauger fishing regulations, given the sauger’s documented maximum size expectancy. Sauger is a very desirable species for anglers to harvest.

Strategies to address the objective include:

  • reduce angler harvest by implementing the existing harvestable slot limit (40-50 cm)
  • monitor walleye populations to assess the success of the size restriction regulation
  • maintain existing seasons, sanctuaries and catch limits for walleye and sauger
  • initiate discussion with First Nations Communities to quantify walleye subsistence harvest
  • develop public/partner opportunities to measure fishing pressure and harvest rates via public reporting (e.g. volunteer angler diary programs)
  • assess the status of sauger populations and the fisheries they support
  • based on harvest and population information, explore merits of the harvestable slot limit (40-50 cm ) for sauger

Objective 2:

Increase natural walleye population recruitment.

Walleye concentrate at specific sites to spawn each spring on rocky shoals in lakes and rapids in rivers. It is important to identify, enhance and protect these sites to help ensure sustainable walleye populations. Walleye spawning success can be impacted by fluctuating water levels and flows. It is important to maintain consistent water levels and flows during the spawning/hatching period of walleye. If the water levels are lowered during this time period, eggs may be killed if they are exposed to air. Excessive flows can impede access to the spawning bed and damage the eggs, while low flows can reduce hatching success by reducing oxygen levels. There are numerous dams and hydropower facilities in FMZ 18 that control flows and levels that could impact walleye spawning success.

New fish species such as black crappie and bluegill have become established in many of the walleye and sauger lakes and rivers in FMZ 18. These species can compete with juvenile walleye and sauger for resources or predate on larval walleye and sauger. Largemouth bass can also have negative impacts on walleye populations by predating on various life stages of walleye (Fayram et al., 2005). A warming climate resulting from climate change is favouring the habitat of warmwater species such as bass and not coolwater species such as walleye and sauger. These changes to habitat and to the fish community may decrease walleye and sauger recruitment and population abundance.

Strategies to address the objective include:

  • work with partners and stakeholders to conduct spawning surveys to identify new spawning locations (e.g. Walleye Watch)
  • undertake assessment of new and existing spawning locations to assess suitability and where warranted, identify rehabilitation priorities
  • create or rehabilitate critical habitat as required
  • identify and share BMP’s to create walleye and sauger spawning habitat
  • identify water level management conflicts related to recruitment and use this information to inform water management planning
  • share spawning location and habitat information with partner agencies to enable the protection of these important areas through land use planning and application of their regulatory mandates (e.g. DFO and Fisheries Act)
  • encourage angler harvest of predator/competitor species (g. bass, panfish) by sharing information on their impacts to walleye and sauger populations, with partners
  • review and encourage research by MNRF and academia to better identify the factors influencing walleye and sauger recruitment
  • identify spawning sites and management actions (e.g. walleye size limits) to enable enforcement activities that ensure population sustainability
  • maintain and where necessary, make recommendation for the establishment of new walleye and sauger sanctuaries
  • for seriously degraded walleye populations where limited recruitment is occurring, consider using rehabilitation stocking as means to allow population recovery, as appropriate (as per Fish Stocking Approach Section)

Objective 3:

Maintain or increase walleye and sauger angling opportunities.

MNRF’s Provincial Fish Strategy and the FMZ 18 Advisory Council places priority on naturally reproducing, self-sustaining populations. A number of strategies are outlined in this document which will increase walleye abundance and improve the quality of angling opportunities. It is also recognized that put-grow-take (PGT) fisheries provide additional angling and harvest opportunities, as well as redirect walleye angling pressure away from naturally reproducing fisheries.

Strategies to address the objective include:

  • maintain existing seasons
  • maintain existing PGT walleye lakes where effective, and explore options for creating new PGT lakes

The goal, objectives and strategies have been summarized in Table 1.

Table 1: walleye management summary

Adapted from tabular format

Walleye management goal:

To increase walleye populations and improve walleye angling and harvesting opportunities

Sauger management goal:

To maintain or possibly increase sauger populations, and improve sauger harvesting opportunities.

Objective 1:

Increase walleye (and determine sauger) abundance and the number of sustainable populations.

Strategies
  • Reduce angler harvest by implementing the existing harvestable slot limit (40cm-50cm).
  • Monitor walleye populations to assess the success of the new size restriction regulation.
  • Maintain existing seasons, sanctuaries and catch limits for walleye and sauger.
  • Initiate discussion with First Nations Communities to quantify walleye subsistence harvest.
  • Develop public/partner opportunities to measure fishing pressure and harvest rates via public reporting (e.g. volunteer angler diary programs).
  • Assess the status of sauger populations and the fisheries they support.
  • Based on harvest and population information, explore merits of the harvestable slot limit (40-50 cm) for sauger.
Progress reviewed by
  • BsM Cycle 3

 

IndicatorBenchmarkTarget
Median area weighted walleye CUEW (all lakes combined from BsM)Current kg/netCurrent kg/net
BsM Proportion of lakes where walleye Biomass ratio (B/Bmax) is > 0.5)Current % of lakesCurrent % of lakes
BsM Proportion of lakes where walleye Mortality rate ratio (Z/M) is <2Current % of lakesCurrent % of lakes
Objective 2:

Increase natural walleye population recruitment.

Strategies
  • Work with partners and stakeholders to conduct spawning surveys to identify new spawning locations (e.g. Walleye Watch).
  • Undertake assessment of new and existing spawning locations to assess suitability and where warranted, identify rehabilitation priorities.
  • Create or rehabilitate critical habitat as required.
  • Identify and share BMP’s to create walleye and sauger spawning habitat.
  • Identify water level management conflicts related to recruitment and use this information to inform water management planning.
  • Share spawning location and habitat information with partner agencies to enable the protection of these important areas through land use planning and application of their regulatory mandates (e.g. DFO and Fisheries Act).
  • Encourage angler harvest of predator/competitor species (e.g. bass, panfish) by sharing information on their impacts to walleye and sauger populations, with partners.
  • Review and encourage research by MNRF and academia to better identify the factors influencing walleye and sauger recruitment.
  • Identify spawning sites and management actions (e.g. walleye size limits) to enable enforcement activities that ensure population sustainability.
  • Maintain and where necessary, make recommendation for the establishment of new walleye and sauger sanctuaries.
  • For seriously degraded walleye populations where limited recruitment is occurring, consider using rehabilitation stocking as means to allow population recovery, as appropriate (as per Fish Stocking Approach Section).
Progress reviewed by
  • BsM Cycle 3
IndicatorBenchmarkTarget
BsM Mean # of Young of the Year (YOY) fish < 150 mmCurrent BsM Mean # of Young of the Year (YOY) fish < 150 mm> Current BsM Mean # of juvenile fish (< 300 mm)
BsM Mean # of juvenile fish (< 300 mm)Current BsM Mean # of juvenile fish (< 300 mm)> Current BsM Mean # of juvenile fish <300mm
BsM Mean # of year classesCurrent BsM Mean # of year classes> Current BsM Mean # of year classes
Objective 3:

Maintain or increase walleye and sauger angling opportunities.

Strategies
  • Maintain existing seasons.
  • Maintain existing PGT walleye lakes where effective, and explore options for creating new PGT lakes.
Progress reviewed by
  • BsM Cycle 4
IndicatorBenchmarkTarget
# of days of the walleye/sauger seasonCurrent # of days of the walleye/sauger season= Current # of days of the walleye/sauger season
# of walleye PGT lakesCurrent # of walleye PGT lakesPotentially > Current # of walleye PGT lakes

Walleye and sauger monitoring and assessment

The provincial BsM program is the primary survey method used to collect fisheries data in Ontario, including walleye. However, most of FMZ 18’s known sauger riverine fisheries are not surveyed by the program. The BsM program will report on the trends and status of fisheries at the FMZ scale and will provide information about fish abundance, population structure, growth, maturity and fishing effort. The fish community will also be assessed to determine changes in species composition over time.

Strategies:

  • adopt the BsM program as the primary index netting (and effort census) survey to assess walleye population status across FMZ 18
  • monitor walleye populations using standard netting protocols (e.g. BsM, FWIN, RIN) to address specific management concerns that arise on lakes and rivers not sampled as part of the BsM program
  • work with partners and stakeholders to conduct spawning surveys to identify new spawning locations (e.g. Walleye Watch)
  • develop public/partner opportunities to measure fishing pressure and harvest rates via public reporting (e.g. volunteer angler diary programs)
  • determine if water quality and habitat variables in potential FMZ 18 waterbodies are sufficient to provide an opportunity for stocking additional PGT coolwater lakes

Current walleye and sauger regulations:

The current season in FMZ 18 is from January 1 to March 1 and from the 2nd Saturday in May to December 31. These dates, along with the existing sanctuary locations, are thought to be effective in protecting many walleye and sauger populations during the spawning period.

The current catch and possession limit for walleye (aggregate limit with sauger) is four (4) for Sport Licence holders and two (2) for Conservation Licence holders, along with a harvestable slot size of 40-50 cm (15.7-19.7 inches). Only fish within the slot may be harvested.