Recent Changes in Lake Michigan's Fish Community and Their Probable Causes, With Emphasis on the Role of the Alewife (Alosa pseudoharengus)

Abstract

Major changes in fish populations occurred in Lake Michigan between the early 1970s and 1984. The abundance of lake trout (Salvelinus namaycush) and several nonnative species of salmonines increased greatly as a result of intensive stocking. The exotic alewife (Alosa pseudoharengus), which had proliferated to extremely high levels of abundance in the mid-1960s, declined, particularly in the early 1980s. We believe that the sharp decline in alewives in the 1980s was caused primarily by poor recruitment during the colder than normal years of 1976–82. Several of Lake Michigan's endemic species of fish appeared to be adversely affected by alewives: bloater (Coregonus hoyi), lake herring (C. artedii), emerald shiner (Notropis atherinoides), yellow perch (Perca flavescens), and deepwater sculpin (Myoxocephalus thompsoni), and possibly spoonhead sculpin (Cottus ricei). All declined when alewives were abundant, and those that did not become rare, i.e. the bloater, perch, and deepwater sculpin recovered when alewives declined. We present evidence suggesting that the mechanism by which alewives affect native species is not by competition for food, as has often been hypothesized, and discuss the possibility that it is predation on early life stages. Despite the decreased availability of alewives in the early 1980s, salmonines continued to eat mainly alewives. The highly abundant alternate prey species were eaten only sparingly, but alewives still may have been abundant enough to meet the forage requirements of salmonines. Two new exotics, the pink salmon (Oncorhynchus gorbuscha) and threespine stickleback (Gasterosteus aculeatus), increased in abundance in the 1980s, and could become detrimental (particularly the salmon) to other species.

Double-crested Cormorant (Phalacrocorax auritus) chick bioenergetics following round goby (Neogobius melanostomus) invasion and implementation of cormorant population control

“…The high energy density of alewife combined with their tendency to school (Schultz, 2004) may make them easier to catch and energetically worth the effort. Alewife, as a key species in Lake Michigan, appear to be a driving force in fish community dynamics (Eck and Brown, 1987; and was abundant in the system in 2000 . Alewife abundance (adult:~300/ha; YOY:~750/ha) spiked in 2000.…”

Old Tales in Recent Context: Current Perspective on Yellow Perch Recruitment in Lake Michigan

“…Alewives are known to alter zooplankton communities (Wells 1970), and during times of high abundance they are effective competitors among secondary consumers (Smith 1970). Yellow perch larvae may not only suffer from this competition for the same food resources but also may occasionally be subject to alewife predation (Crowder 1980;Eck and Wells 1987). Given the alewife and yellow perch population trends in Lake Michigan, neither competition nor predation should be discussed separately.…”

Long‐term changes in legacy trace organic contaminants and mercury in Lake Ontario salmon in relation to source controls, trophodynamics, and climatic variability

“…The ecological and physiological responses of alewife and coho and chinook salmon to rising temperatures might explain the negative correlation between contaminant concentrations and temperature. Survival rates of youngof-the-year (YOY) alewife increase with increasing ambient water temperatures (Kellogg 1982;Eck and Wells 1987;Casselman et al 1999). Increased YOY survival during warm years would increase competition for resources within the cohort, thereby reducing the probability that individuals recruit to larger, more contaminated size classes.…”