Diet and Prey Selection of Alewives in Lake Michigan: Seasonal, Depth, and Interannual Patterns

To evaluate the current diet of alewives Alosa pseudoharengus and interactions with their prey in light of recent changes in Lake Michigan, we determined the seasonal diet and prey selectivity of large (>100 mm total length) and small (<100 mm) alewives in southeastern Lake Michigan. Selectivity and diet were evaluated on a biomass basis for alewives collected near Muskegon, Michigan, during June, July−August, and October 1999–2001. Fish were sampled from three depth zones: shallow (15–25 m), transitional (35–55 m), and deep (65–90 m). Prey selectivity and diet patterns indicated that alewives had considerable flexibility in adjusting to prey availability, which varied by season, depth zone, and year. Although small copepods were an abundant prey item throughout the year and in all depth zones, they were mainly important in the diet (large and small alewives) in June and at the shallow stations, where many of the other prey types were not available. Despite declining numbers, Diporeia continued to be important for large alewives in spring, particularly at the transitional and deep stations, where their biomass was many times higher than that of other prey. During summer, large alewives selected either Bythotrephes longimanus or Mysis relicta in all depth zones and years. The diet of large alewives consisted mainly of Mysis in July 1999 and August 2001, whereas in August 2000 mainly Bosmina were eaten. During October, Mysis and Bythotrephes, along with large zooplankters (Daphnia spp. and large calanoid copepods), were selected and were most important in the diet of large alewives. In contrast, only the large zooplankton were selected and were important prey for the small alewives in fall. Annual, seasonal, and depth differences in prey biomass as well as differences in alewife size all influenced diet and selectivity patterns.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/141716/1/tafs1068.pd

Declines in the energy content of yearling non‐native alewife associated with lower food web changes in Lake Michigan

Juveniles of non‐native alewife, Alosa pseudoharengus (Wilson), were collected in Lake Michigan in 1998, 1999, 2010, 2011 and 2013 to evaluate changes in energy content during a period of major ecosystem changes. Consistent with historical data, energy content of yearling alewife declined from late winter into late spring and was at its lowest point in June. Energy density and length‐adjusted, entire‐body energy were lower in 2010, 2011 and 2013 than in 1998 and 1999. Energy losses over the first winter in the lake were more severe for the 2010 year class (56% decrease) than for the 1998 year class (28% decrease). Alewife diets in late spring of 2010–2013 reflected the loss of major prey such as Diporeia spp. and a shift towards lower energy prey. The recent decline in energy content of yearling alewife can be linked to recent changes in productivity and abundance of key components of the lower food web of Lake Michigan following the dreissenid invasion.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/109567/1/fme12092.pd

Behind the scenes of the digital museum of information retrieval research

As more and more of the world becomes digital, and documents become easily available over the Internet, we are suddenly able to access all kinds of information. The downside of this however is that information that is not digital becomes less accessed, and is liable to be lost to us and to future generations. Whereas there are many scanning projects underway, such as Google books and the Open Library Alliance, these projects are not going to know about, much less find, the specialized scientific literature within various fields. This short paper describes the beginnings of a project to digitize some of the older literature in the information retrieval field. The paper finishes with some thoughts for future work on making more of our IR literature available for searching

Effects of Activity and Energy Budget Balancing Algorithm on Laboratory Performance of a Fish Bioenergetics Model

We evaluated the performance of the Wisconsin bioenergetics model for lake trout Salvelinus namaycush that were fed ad libitum in laboratory tanks under regimes of low activity and high activity. In addition, we compared model performance under two different model algorithms: (1) balancing the lake trout energy budget on day t based on lake trout energy density on day t and (2) balancing the lake trout energy budget on day t based on lake trout energy density on day t + 1. Results indicated that the model significantly underestimated consumption for both inactive and active lake trout when algorithm 1 was used and that the degree of underestimation was similar for the two activity levels. In contrast, model performance substantially improved when using algorithm 2, as no detectable bias was found in model predictions of consumption for inactive fish and only a slight degree of overestimation was detected for active fish. The energy budget was accurately balanced by using algorithm 2 but not by using algorithm 1. Based on the results of this study, we recommend the use of algorithm 2 to estimate food consumption by fish in the field. Our study results highlight the importance of accurately accounting for changes in fish energy density when balancing the energy budget; furthermore, these results have implications for the science of evaluating fish bioenergetics model performance and for more accurate estimation of food consumption by fish in the field when fish energy density undergoes relatively rapid changes.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/141002/1/tafs1328.pd

Corrigendum to “Recent changes in primary production and phytoplankton in the offshore region of southeastern Lake Michigan” [J. Great Lakes Res. 36 (Supplement 3) (2010) 20–29]

The authors regret that there is an error on the labels of two figures that were published in the paper referenced above. For Figs. 5b, c, and d and 7b and c the y-axes have the wrong labels. The following are the correct y-axis labels: Fig. 5b — the y-axis should range from 0 to 5, Fig. 5c — the y-axis should range from 0 to 2, Fig. 5d — the y-axis label should range from 0 to 3, Fig. 7b — the y-axis should range from 0 to 40, and for Fig. 7c — the y-axis should range from 0 to 50

From Blind Spot to Crucial Concept: On the Role of Animal Welfare in Food System Changes towards Circular Agriculture

Agriculture in Western Europe has become efficient and productive but at a cost. The quality of biodiversity, soil, air, and water has been compromised. In the search for ways to ensure food security and meet the challenges of climate change, new production systems have been proposed. One of these is the transition to circular agriculture: closing the cycles of nutrients and other resources to minimise losses and end the impact on climate change. This development aims to address existing problems in food production but also raises questions about animal health and welfare. Although the role animals can play in this development is not ignored, the animal welfare dimension of circular agriculture seems to be overlooked. We argue that this is a problem both for the success of circular agriculture and for the animals involved. To substantiate this claim, we analyse the background to this lack of attention, which we find in (a) the way circular agriculture is conceptualised; (b) the institutional hurdles related to the legal, political and economic context; and (c) the concept of animal welfare, which requires further innovation. By analysing these aspects, we develop stepping stones for an animal-welfare inclusive concept of circular agriculture. These stepping stones include: recognising the animal as a participant with its own interests in the innovation towards circular agriculture; using a dynamic concept of animal welfare; a concept of circularity that provides space for social values, including animal welfare; and attention to institutional innovation by improving public engagement and building trust