Response of yellow perch in Les Cheneaux Islands,Lake Huron to declining numbers of double-crested cormorants stemming from control activities

The yellow perch (Perca flavescens) fishery of the Les Cheneaux Islands region of Lake Huron experienced an unprecedented collapse in 2000. Immediately prior to the collapse was the proliferation of double-crested cormorants (Phalacrocorax auritus) in the area. Subsequent investigations established that double-crested cormorant predation was chief among the forces shaping the local yellow perch population and contributing to the collapse of the fishery. A double-crested cormorant control program was implemented in 2004 with the objective of benefiting the yellow perch population and fishery. This study used creel survey and gillnet fish community assessment data to evaluate the response of the yellow perch population and fishery. In all, seven key yellow perch metrics were analyzed using regression analysis with double-crested cormorant abundance as the independent variable. As double-crested cormorant abundance declined, yellow perch abundance increased, total mortality rate decreased, the angler catch rate and harvest in the recreational fishery improved, yellow perch growth rate declined and mean age increased. Increased yellow perch recruitment was documented since 2003 but it was the longevity of these year classes, (improved survival) as much or more than their magnitude of the year class, that allowed for the progress towards recovery. Questions facing managers are the sustainable level of double-crested cormorants in the region and the long term prognosis for the yellow perch fishery to fully recover to pre-double-crested cormorant levels.