Chinook key in Lake Michigan harbor survey

Chicago — Thanks to the work of DNR biologists, Lake Michigan anglers have gotten a glimpse of what’s happening with major sportfish in and around the Chicago harbors.

In “Salmonid Community of Lake Michigan: 2014 Fall Harbor Assessment,” a team led by DNR’s Steven Robillard and Kristen A. Patterson of the Illinois Natural History Survey provided an update of salmon and trout populations in popular fishing spots along the urban shoreline.

The  annual survey, funded by Federal Aid in Sport Fish Restoration Funds, allows fisheries biologists to track salmon and trout that were previously tagged or clipped.

In 2014, North Point Marina, the south harbor at Waukegan, Diversey Harbor and adjacent Lincoln Park Lagoon, and the inner harbor at Jackson Park were sampled weekly between mid- September and mid-November. A total of 219 salmonids were captured, with chinook representing the highest proportion (41.1 percent), followed by coho (28.8 percent) and brown trout (23.8 percent).

Rainbow trout represented 6.4 percent of the total catch.

“We assess the return rate of salmonids to the harbors in which they are stocked by clipping off different fins in different years and monitoring the incidence of fin clips on salmonids returning to the harbors in the fall,” authors of the fall survey noted.

Objectives of the fall salmonid harbor sampling are to collect fish flesh samples to update the Illinois Fish Consumption Advisory, collect data on returning fin-clipped fish and assess movements and fidelity to stocking sites and collect information on the condition and abundance of returning fish to address questions regarding health of the fish and the effects on the forage base.

“Since the Illinois shoreline of Lake Michigan lacks permanent flowing tributaries, salmon and trout are stocked in harbors,” Patterson and Robillard noted. “Adult fish that return to these harbors in the fall are sampled by Lake Michigan Program staff.”

Some of the findings from the fall 2014 survey:

  • In 2014, 62 percent of chinook captured with coded-wire tags were caught in the same harbor they were stocked into. That number was 80 percent in 2012 – the first sampling year after the project was initiated. 
  • Fall catches for all salmonids combined was highest in Jackson Harbor (12.3 fish per hour). It was 8.6 fish per hour at Waukegan Harbor and 5.6 fish per hour at Diversey Harbor. North Point Marina’s rate  dropped to the lowest out of all harbors sampled, with 4.8 fish per hour of effort. 
  • Chinook catch rates in 2014 was highest in Waukegan Harbor (6.3 fish per hour), followed by Jackson Harbor (2.7 fish per hour), Diversey Harbor (1.5 fish per hour), and North Point Marina (1.1 fish per hour). 
  • Coho catch rates were highest at Jackson Harbor (7.3 fish per hour). 
  • A total of 14 rainbow trout were collected in 2014. Half of them had a fin clip indicating Illinois origin.
  • The total number of brown trout captured in 2014 (52) was comparable to 2013 (58), yet contributed substantially more to the catch in 2014 (24 percent) compared to last year (12 percent). 
  • Catch rates for brown trout in 2014 were above the 15-year average at Jackson and Diversey harbors, but below at Waukegan Harbor and North Point Marina. 
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