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Overview for Discussions Regarding 2018 Salmon and Trout Stocking Levels in Lake Ontario

Key Points:

  • In 2016, Lake Ontario fisheries management agencies were concerned about declining numbers of adult Alewife over the next few years due to poor Alewife production in 2013 and 2014.
  • In 2016, the Lake Ontario Committee (New York State Department of Environmental Conservation [DEC] and the Ontario Ministry of Natural Resources and Forestry [OMNRF]) announced that stocking levels for Chinook Salmon and Lake Trout would be adjusted down 20% in 2017 to reduce predator demand on adult Alewife in order to protect the valuable fishery.
  • In 2017, the lake wide spring Alewife survey showed a strong first step toward recovery with a record number of young Alewife produced in 2016 and caught as age-1 fish in 2017.
  • The record numbers of Alewife produced in 2016 is great news, but additional strong Alewife reproduction and survival is needed in upcoming years to rebuild the adult population.
  • Lake Ontario's Alewife population is currently composed of primarily Age 1, 2 and 5 fish.
  • New York and Ontario will maintain 2018 stocking levels at the adjusted 2017 targets while continuing to monitor the status of the fishery.
  • Chinook Salmon fishing in 2017 has been excellent. Lake Ontario should continue to provide a world class fishery supported by stocking and significant wild Chinook Salmon production.
  • The Lake Ontario Committee remains optimistic about the state of the fishery and its future.

Lake Ontario's World Class Fishery

  • Lake Ontario supports a world class fishery for trout and salmon and produces the largest Chinook Salmon in the Great Lakes, with some individuals exceeding 40 pounds.
  • The primary prey fish in Lake Ontario is the Alewife, a type of herring native to the Atlantic Ocean that invaded the Great Lakes over 100 years ago.
  • Chinook Salmon feed almost exclusively on Alewife, requiring large numbers of Alewife to support a voracious appetite that allows a salmon to grow to over 30 pounds in four years.

Bi-national Management and Cooperation

  • The DEC and the OMNRF work together as the Lake Ontario Committee under the Great Lakes Fishery Commission's Joint Strategic Plan for Management of Great Lakes Fisheries to monitor the health of the fishery, establish joint management objectives and coordinate stocking and research efforts.
  • Lake Ontario's Alewife population is monitored cooperatively by DEC, OMNRF and the US Geological Survey (USGS).
  • Up until 2015, spring prey-fish surveys were limited to US waters and therefore prey fish estimates were based on only 50% of the lake.
  • Starting in 2016, due to additional OMNRF capacity in Ontario and under the leadership of the USGS, an enhanced, lake-wide prey fish survey was implemented.
  • The maps in Figure 1 show previous survey coverage and the new, lake wide coverage.
  • The new lake-wide survey increases our confidence in Alewife assessment.
  • The sizes and ages of Alewife caught in NY and Ontario waters in 2016 and 2017 were the same, indicating that poor reproduction in 2013 and 2014 was a lakewide effect.
Lake Ontario alewife bottom trawling sites
Figure 1. Maps showing historic Alewife bottom trawling sites (top), and new, enhanced coverage
in 2017 (bottom).

The 2017 Alewife Survey (Figure 2)

Lake Ontario alewife bottom trawl catch rates by year
Figure 2. Average numbers of yearling (left) and adult (right) Alewife caught in Lake Ontario bottom trawl survey, 1997-2017. Red "squares" represent trawling results from Ontario (CA) waters during enhanced surveys conducted in 2016 and 2017. The black diamonds represent estimates based on combined US and Ontario trawl results.
  • Bottom trawl survey results in 2017 indicate a dramatic increase in yearling (age-1) Alewife numbers in NY waters (black dots); the increase was much less pronounced in Ontario (red squares) waters (Figure 1, left panel). Catches of adult (age-2 and older) Alewife in 2017 also increased in NY waters relative to 2016, however, the opposite was true for trawls performed in Ontario waters (Figure 2, right panel).
  • These differences illustrate the importance of bottom trawling throughout the lake.
  • The relative numbers of Alewife (bar height; y axis) at a given size (inches on x axis) and age (color) in 2017 are presented in Figure 3.
  • Very high catches of yearling (age-1) Alewife from the 2016 year class are represented by the green bars in Figure 3.
  • In 2017, "larger" size Alewife that support both Alewife spawning and food for large Chinook salmon are primarily composed of age-2 (yellow bars; 2015 year class) and age-5 fish (black bars; 2012 year class).
  • As expected, catches of age-3 (2014 year class; red bars) and age-4 (2013 year class; blue bars) Alewife were poor. The extreme long, cold winters of 2013/2014 and 2014/2015 contributed to the poor 2013 and 2014 year classes, and these poor year classes will continue to affect the overall stability of Lake Ontario's Alewife population for several more years.
  • The adult Alewife population in 2018 will be composed primarily of Alewife ages 2, 3, and 6. The Lake Ontario Committee is cautiously optimistic that the 2018 Alewife population can support both successful spawning (given favorable weather conditions) and prey demand from Chinook Salmon, Lake Trout and other trout and salmon.
2017 Lake Ontario size class structure graph
Figure 3. The relative abundance of Alewife in 2017 arranged by age (color) and length. For example, the
green bars represent the 2016 Alewife year class (spawned in 2016) and measured at age 1 in 2017. The
height of each green bar is the relative number of age 1 alewife at a given total length (inches).

Summary and Next Steps

  • The strong 2016 Alewife year class is a very positive sign, but it does not change the very poor year classes from 2013 and 2014 and the impact those poor year classes will have on the adult Alewife population in upcoming years.
  • A cautious approach to sustaining the adult Alewife population to feed predators and successfully reproduce is needed at least through 2019. The LOC believes that maintaining Chinook Salmon and Lake Trout stocking at 2017 levels, coupled with natural reproduction, should sustain good fishing opportunities in future years.
  • New York will hold public meetings during late August and September to discuss this decision.


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