| Fishery managers are considering the use of low-head barrier dams in as many as 100 Great Lakes tributary streams for sea lamprey control purposes. Barriers prevent reproductive migrations of the exotic sea lamprey but may also impact non-target species. Complete species lists for barrier candidate streams are a prerequisite for ensuring that barriers do not cause the loss of species of concern. Here, I examine (1) the amount of sampling effort required to detect a target percentage of the estimated number of species in the watershed, (2) strategies to increase the efficiency of species inventories, and (3) the adequacy of exiting survey data for characterizing species composition in Great Lakes streams. I found that sampling effort requirements increased exponentially as the targeted percentage of estimated species richness rose. At the stream reach level, sampling an intermediate length of stream maximized rates of species accumulation. At the watershed level, allocating sampling effort to higher order sections of the watershed increased rates of species accumulation, however, headwater species were likely to be consistently missed when more than 70% of sampling effort was allocated to higher order strata. Existing lists compiled from multiple, repeated surveys contained more species than field lists, but when only a few one-time surveys were available existing lists were considerably smaller than field lists. In addition, we found (1) errors in existing data and (2) older lists may not reflect the current species composition of the stream. |
