Results In for 2014 Juvenile Lake Trout Survey
in Northern Lake Huron
BY ADAM KOWALSKI, ALPENA FWCO
This spring staff from the Alpena Fish and Wildlife Conservation Office (FWCO) completed a juvenile lake trout survey in 1836 treaty waters of northern Lake Huron (Alpena, Michigan north to Hammond Bay). This study was designed to index juvenile lake trout abundance and collect biological data on juvenile lake trout for population models developed for lake trout stocks in northern Lake Huron.
During the survey, Alpena FWCO staff conducted 21 graded-mesh gill net lifts at randomly selected ports in two Lake Huron lake trout management units: MH-1 (Rogers City north) and MH-2 (Rogers City south to Black River). Biological data were collected from all lake trout encountered, including length, weight, sex and maturity, diet, visceral fat index, and lamprey wounding. Similar biological data were collected from non-target species. Tissue samples were taken from unclipped (presumably wild) lake trout for future DNA analysis.
Thirty-three lake trout less than 500 millimeters in length (a commonly accepted size cutoff for juveniles) were captured during the survey. Eighteen of the 33 juveniles were of wild origin (based on the absence of fin clips). Two of the fish captured were less than 300 millimeters in length and one of those was wild. Of the total juvenile late trout catch, the shallow depth strata (100-150 feet) contained 54% and the deep strata (greater than 150 feet) contained 46%. Catch-per-unit effort (CPE) of juvenile lake trout was one fish per 1000 feet of net. These catch rates are similar to 2012 and lower than 2013.
Surveys indicate that wild year classes from 2009 and 2010 have added significantly to the lake trout in the population in northern Lake Huron, although subsequent year classes appear to be less abundant. These past years have given us a better understanding of the abundance and distribution of juvenile lake trout in northern Lake Huron, where positive steps toward lake trout rehabilitation continue.