**The title, authors, and abstract for this completion report are provided below. For a copy of the completion report, please contact the GLFC via e-mail or via telephone at 734-662-3209**
Host-size selection and lethality of sea lamprey on lake sturgeon
Trent M. Sutton 1, Holly K. Patrick1, and William D. Swink2
1Purdue University , Department of Forestry and Natural Resources, 195 Marsteller Street, West Lafayette, IN, 47907
2USGS-Hammond Bay Biological Station, 11188 Ray Road, Millersburg, MI 49759
Parasitism by sea lampreys Petromyzon marinus may contribute to the limited recovery of imperiled lake sturgeon Acipenser fulvescens in the Great Lakes. Our study objectives were to examine survival, condition, growth, and changes in hematology, blood chemistry, and histological condition of major organs of four size classes of lake sturgeon following a single sea lamprey attack. In addition, we developed a sea lamprey wound classification scheme for lake sturgeon and an associated photographic dichotomous key. Lake sturgeon from one of four size groups (I: 470- to 570-mm fork length [FL]; II: 570- to 650-mm FL; III: 650- to 760-mm FL; and IV: 950- to 1,500-mm FL) were individually subjected to a sea lamprey attack in a series of 55 experimental trials. Direct mortality of lake sturgeon, resulting from acute anemia following an attack, was greatest for smaller lake sturgeon (I: 11%; II: 31%; III: 8%; IV: 0%). Similarly, indirect mortalities resulting from secondary fungal infection were also size dependent (I: 11%; II: 19%; III: 8%; IV: 0%). Greater than 50% of sea lamprey attacks occurred on the ventral surface of the rostrum or pectoral fin axils, and attachment at these locations typically resulted in mortality of the host. The new classification system has the same general structure as the current scheme for scaled teleosts (type-A and -B; stages I-IV), but the criteria are specific to sea lamprey marks on lake sturgeon. Changes in hematological and blood-chemistry parameters were more pronounced for smaller hosts, with significant declines occurring in hemoglobin and plasma protein for size classes I and II and in hematocrit for size classes I, II, and III. An index of histological spleen condition was developed, but I was unable to develop indices for histological condition of the liver or kidney. Results from this study indicate that lake sturgeon survival depends on host-body size and location of sea lamprey attachment. Further, our recommend the use of our dichotomous key to augment the existing sea lamprey wound classification schemes and provide a standardized means for assessing and monitoring of lake sturgeon populations.