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Summary of Impediments for Lake Herring in the Great Lakes Overall the loss of stocks in the Great Lakes was considered the biggest impediment (Table 1, Fig. 2). This would strongly argue for protection of the existing stocks through reduction of targeted fisheries and by-catch by commercial and sport fisheries until the size and amount of genetic diversity in existing populations can be determined. In the event that existing stocks are too small and genetically depleted relative to historic stocks consideration should be given to restoration. The impact of non-native biota on lake herring stocks in the Great Lakes represents a large and poorly understood group of impediments. now facing lake herring stocks in the Great Lakes. The list includes alewives, rainbow smelt, sea lamprey (Petromyzon marinus), cormorants (Phalacrocorax auritus), dreissenids (Dreissena polymorpha), round gobies (Neogobius melanostomus), Bythotrephes longimanus, and Cercopagis pengoi. Although alewives have been in the lakes since the late 1800s, much of the evidence linking them to declines in lake herring abundance is anecdotal, speculative, and circumstantial. Negative statistical correlations between the abundance of lake herring and alewives are lacking as are mechanisms that would explain such correlations. The inability to secure robust qualitative and quantitative data linking the impacts of non-native species on lake herring will become only more daunting and complex with the increasing pace of invasions in the Great Lakes. Nevertheless we can neither anticipate nor expect controls on existing or future invasive species without first producing more tangible evidence of effect than has characterized the record to date. 10
Table 1: Summary of impediment ranking across all groups by lake. The total possible score for each individual lake is 390 points. For individual criteria the total possible score for all lakes is 75 points, based on a total of 5 points for each of the five lakes for each of the three groups. Impediments: Superior Huron Michigan Erie Ontario All a. Habitat Degradation a.a. spawning 3 6 5 6 10 30 a.a. egg incubation 2 5 4 5 5 21 a.b. juvenile 3 2 2 2 2 11 a.c. adult 3 4 4 4 4 15 b. Contaminants 4 5 7 6 7 29 c. Exploitation a. commercial-i. direct 8 8 3 2 2 23 a. commercial-ii. Bycatch 3 3 5 6 5 22 b. recreational- 3 5 4 3 3 18 d. Non-native biota a. fish, i. piscivores 4 6 7 10 6 33 a. fish, ii. Planktivores 3 11 13 6 13 46 a. fish, iii. Benthivores 3 8 7 5 9 32 a. fish, iv. Parasites 4 8 8 3 7 30 b. invert., i. zooplankton 4 3 3 1 5 16 b. invert., ii. Dreissenids 3 8 7 9 11 38 c. birds cormorants 3 5 5 6 6 25 e. Native biota i. piscivores 3 5 5 7 6 26 ii. planktivores 3 3 3 3 3 12 iii. benthivores 3 4 4 2 3 22 iv. invertebrates 3 4 4 5 7 23 f. Genetics a. hybridization 4 3 6 7 5 25 b. diversity 4 7 13 13 13 50 g. Stock structure a. age 3 3 1 1 1 9 b. sex-ratio 3 1 1 1 1 7 h. Spawning stock a. magnitude/size 6 14 15 15 14 64 b. spawning site fidelity 1 0 0 0 0 1 i. Climate 2 4 4 6 6 22 TOTAL 88 135 140 134 149 One group with insufficient information Two groups with insufficient information Three groups with insufficient information 11
Page 1 and 2: GREAT LAKES FISHERY COMMISSION 2004
Page 3 and 4: Status and Assessment, Research, an
Page 5 and 6: Executive Summary The Great Lakes R
Page 7 and 8: Introduction The lake herring (Core
Page 9 and 10: Table 1: Potential Impediments to L
Page 11: Based on index netting, lake herrin
Page 15 and 16: Summary of Knowledge Gaps for Lake
Page 17 and 18: Figure 3: Summary of knowledge gaps
Page 19 and 20: 2/27/2004 Alewives and to a lesser
Page 21 and 22: 2/27/2004 Summary of Restoration Ne
Page 23 and 24: 2/27/2004 References Bence, J. R. a
Page 25 and 26: 2/27/2004 Appendix A Agenda Lake He
Page 27 and 28: 2/27/2004 Appendix B Participant Li
Page 29 and 30: 2/27/2004 Appendix C Summary of Sta
Page 31 and 32: 2/27/2004 Explanatory notes for imp
Page 33 and 34: 2/27/2004 Research Questions for Gr
Page 35 and 36: 2/27/2004 Appendix E Summary of Dis
Page 37 and 38: 2/27/2004 e. Native biota • Pisci
Page 39 and 40: 2/27/2004 Final Charge 2 for Group
Page 41 and 42: 2/27/2004 Explanatory notes for Gro
Page 43 and 44: 2/27/2004 Final Charge 1 for Group
Page 45 and 46: 2/27/2004 Issue: What are the early

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