Changes in seasonal energy dynamics of alewife (Alosa pseudoharengus) in Lake Michigan after invasion of dreissenid mussels

Abstract

The dreissenid mussel invasion of Lake Michigan during the 1990s has been linked to a concomitant decrease in the abundance of the amphipod Diporeia. We tracked the seasonal energy dynamics of alewife (Alosa pseudoharengus) in Lake Michigan during 2002–2004 and compared our findings with previously published results for years 1979–1981. Adult alewife energy density exhibited a pronounced seasonal cycle during both the pre-invasion and post-invasion periods, with energy density in October or November nearly twice as high as that in early summer. However, on average, adult alewife energy density was 23% lower during the post-invasion period compared with the pre-invasion period. This significant decline in energy density was attributable to decreased importance of Diporeia in adult alewife diet. In contrast, energy density of juvenile alewives did not significantly differ between the pre-invasion and post-invasion periods. To attain a weight of 8 kg by age 4, bioenergetics modeling indicated that a Chinook salmon (Oncorhynchus tshawytscha) in Lake Michigan would have to consume 22.1% more alewives during the post-invasion period compared with the pre-invasion period.

Temporal trends in Mysis relicta abundance, production, and life-history characteristics in southeastern Lake Michigan

“…However, production appeared to have declined in 1999-2000 and continued to be low into 2007-2008. Recent work indicates that alewife condition and growth have declined in Lake Michigan and despite doubling their consumption of Mysis, individual fish total consumption still declined on average 31%, possibly because Mysis production is inadequate to fully compensate for the loss of prey such as Diporeia even at low fish abundances (Madenjian et al, 2003(Madenjian et al, , 2006Pothoven and Madenjian, 2008). Changes in alewife condition or abundance ultimately impact stocked salmonine populations that prey upon them (Madenjian et al, 2006).…”

Measures of larval lake whitefish length and abundance as early predictors of year-class strength in Lake Michigan

“…Alewife condition declined by about 14% after 1995 (Madenjian et al 2003), suggesting a link between reduced alewife condition and diporeia abundance. More recently, Madenjian et al (2006) (also see the Status of Planktivore Populations chapter) reexamined the energy density of alewife using bomb calorimetry. Peak energy density of alewife >150 mm in length in the fall declined by 21%, from 9,641 J/g in 1979-1981 (Stewart and Binkowski 1986) to about 7,680 J/g in 2002-2003.…”

Variation in Lake Michigan Alewife (Alosa pseudoharengus) Thiaminase and Fatty Acids Composition

“…Environmental conditions such as season and diet have been reported to affect the growth and lipid content of Great Lakes alewife (Madenjian et al 2006), but factors that influence their thiaminase activity are unknown. The Great Lakes food web has been and continues to be in transition.…”