Great Lakes Fishery Commission

Updated 2024-12-13 16:26:13

Lake Huron -> 5.0 Coregonine (Lake Whitefish and Cisco) -> Lake Whitefish Yield

5.1.1. Combined annual yield of Lake Whitefish and ciscoes is at least 3.8 million kg

The Coregonines sub-family of ciscoes and whitefishes and their habitats in the Great Lakes were severely impacted by anthropogenic stressors (Bunnell et al., 2023). In a recent synthesis of ciscoes in the Great Lakes, for example, Eshenroder et al. (2016) reported that at least 70% of their diversity has been lost. The coregonines of Lake Huron were comprised historically of Lake Whitefish (Coregonus clupeaformis), Round Whitefish (Prosopium cylindraveum), two species of shallowwater ciscoes, and seven deepwater ciscoes. The deepwater ciscoes comprised Coregonus alpenae, C. hoyi, C. zenithicus, C. kiyi, C. johannae, C. nigripinnis, and C. reighardi (Eshenroder et al., 2016). The deepwater cisco subcomplex was altered dramatically throughout the 19th and 20th centuries causing five deepwater ciscoes to introgress into a hybrid swarm across all three basins (Eshenroder et al., 2016). Today, only two ciscoes species occur in Lake Huron: Cisco (C. artedi) and Bloater (C. hoyi). Bloater still occur lake-wide and exhibit high variation in abundance and recruitment (Collingsworth et al., 2014). Contemporary Bloater, however, have four morphological differences from those described by Koelz (1929), and Eshenroder et al. (2016) hypothesized that contemporary Bloater may instead be a hybrid resulting from introgression that occurred sometime after 1956.

Average annual lake-wide yield of Lake Whitefish and ciscoes during the current reporting period was 1.1 million kg (range: 0.8 – 1.4 million kg), which was 2.7 million kg below the target of 3.8 million kg (Figure 1) and roughly half the mean yield observed in the previous reporting period (2.0 million kg).  Combined yield of Lake Whitefish and ciscoes has been declining since 1997 and has been below target every year since 2003 (Figure 1). Overall coregonine yield has been dominated by Lake Whitefish (Figure 2), with other coregonines harvested only sporadically in commercial, recreational, and subsistence fisheries.  Lake-wide wide commercial yield of Lake Whitefish declined from 1.4 million kg in 2017 to 1.1 million kg in 2022 (Figure 2), and decreased harvest has been observed in nearly all areas and sub-basins (Figure 3). Declining population abundances of Lake Whitefish are occurring primarily due to a decline in the recruitment of juvenile fish (ages 1–4 years) into the population (Ebener et al., 2021).  Poor recruitment may be linked to the establishment of dreissenid mussels which have reduced zooplankton availability for larval Lake Whitefish, leading to poor growth and survival at this critical life stage. Following dreissenid establishment, larval densities and growth were on average only 23% and 55% of historical values, respectively. Results suggest that juvenile recruitment is being limited at the larval stage, owing to overall lower larval production, and potentially exacerbated by slower growth (Cunningham and Dunlop, 2023).

Historically, Cisco was one of the most abundant pelagic fishes, found “out of virtually every port on Lake Huron, in the North Channel, and Georgian Bay” (George, 2019). Cisco continues to be common in Georgian Bay, the North Channel, St. Marys River, and the very northern Michigan waters of Lake Huron’s main basin. Sporadic catches of juveniles in central and southern main-basin index netting indicate that Cisco is widely spread in Ontario waters but less so in Michigan waters (Cotrill et al., 2020).  Total yield has remained essentially unchanged over the past 40 years (Figure 4), with commercial yield averaging 4800 kg per year during the reporting period (2018-2022).  Most of the reported catches are from Ontario waters (Figure 4). In U.S. waters of the main basin, Cisco is largely restricted to areas from the Straits of Mackinac to Drummond Island. Recently, rehabilitation strategies for the western main basin have received increased focus in recent years because fishery agencies are recognizing the important ecological role that Cisco historically played in the pelagic fish community. The Cisco stocking in Saginaw Bay in Lake Huron begun in 2018 with implementation of a 10-year stocking.

Combined commercial yield (millions of kg) of Lake Whitefish and ciscoes in Lake Huron, 1990-2022. Horizontal line indicates the target yield of 3.8 million kg. Yields do not include recreational harvest.

Commercial yield (millions of kg) of all coregonines combined and for Lake Whitefish alone in Lake Huron, 1990-2022. Yields do not include recreational harvest.

Commercial yield (thousands of kg) of Lake Whitefish by lake basin in Lake Huron, 1980-2022.

Commercial yield (thousands of kg) of Cisco by lake basin in Lake Huron, 1980-2020.