North Temperate Lakes
US Long-Term Ecological Research Network

Eradication via destratification: whole-lake mixing to selectively remove rainbow smelt, a cold-water invasive species.

Abstract
Rainbow smelt (Osmerus mordax) are an invasive species associated with several negative changes to lake ecosystems in northern Wisconsin. We combined empirically based bioenergetics models with empirically based hydrodynamic models to assess lake destratification as a potential rainbow smelt eradication method. The dataset reported here is the otolith data from 20 age 1plus individuals.
Dataset ID
266
Date Range
-
LTER Keywords
Metadata Provider
Methods
Rainbow smelt were sampled from Crystal Lake to obtain age and growth estimates. Samples were taken using vertical gillnets and beach seines during late July and early August of 2009. Annual growth was estimated using sectioned sagittal otoliths from 25 individuals spanning the observed length range (31–164 mm). Otoliths were mounted in epoxy and a transverse section was removed using a low-speed saw. Annual growth estimates were measured along a radius from the origin to the edge oriented perpendicular to annual growth rings. Age-specific length was estimated using the biological intercept method of back-calculation. The biological intercept was calculated by applying the average rainbow smelt otolith radius at time of hatch, to our observed linear relationship of natural-log-transformed total otolith radius and total fish length. Of the 25 individuals aged using otoliths, 5 were YOYs. As a result, annual growth was only back-calculated using the 20 older individuals. Weight at age was determined from back-calculated lengths using a weight–length relationship derived from 100 individuals captured during late July and early August of 2009.
Related Sites
Version Number
22

Biocomplexity at North Temperate Lakes LTER; Whole Lake Manipulations: Rainbow Smelt Removal 2001 - 2009

Abstract
Rainbow smelt (Osmerus mordax) are a harmful invasive species in lakes of northern Wisconsin. Smelt were first detected in Sparkling Lake, Vilas county, WI in 1980 and their population has since increased dramatically. We attempt to remove rainbow smelt from Sparkling Lake through a combined strategy of harvest and predation. If successful, such a strategy might be employed to restore other Wisconsin lakes invaded by smelt to a more natural species assemblage without resorting to piscicides. The data sets presented here report the harvest component of smelt removal. An assessment of the rainbow smelt population, supplementing annual LTER data, was performed during the late summer of 2001. The spring removal effort began in 2002 at ice out using multiple gear types. In 2002, the removal effort also continued from mid to late summer using horizontal gill nets. However, from 2003-2009 we took advantage of smelt spawning behavior and our efforts were condensed to a spring removal at ice-off and we utilized only fyke nets. The total weight of each catch was recorded and length-weights as well as sex ratios were documented for a subset of the catch from each removal event. The removal effort resulted in the removal of the majority of the adult population multiple times. However, smelt are a robust species and the population continuously rebounded from large removal years. As a result, catches have fluctuated from 16kg to nearly two tons. We have observed an overall reduction in fish size and an increase in the proportion of males to females. Sampling Frequency: annually
Dataset ID
218
Date Range
-
LTER Keywords
Maintenance
completed
Metadata Provider
Methods
Setting NetsSet nets in areas of high catch first, moving clockwise around the lake.GPS location of netRecord dates in that locationNumber nets consecutively from first net set. (Nets do not need to be pulled in order they were set.) If a net is moved, keep the same number and add an a, b, c, etc after.Sketch net location on a map with the net number (keep with In-Boat data sheets)Pulling NetsTake lake map with net numbers and In-Boat data sheetRecord date, time, collectors namesAt each net, record net number, number of bags and any comments (note anything unusual)For a zero catch… note if the net was fishing (tipped over, twisted, etc). If there were no problems write NORMAL SET.Try to set the net in exactly the same location. (Over burlap if applicable)Data CollectionIf there is not enough time, please follow this order for priority of data collection.Daily CatchUse Daily Catch sheetRecord date, net number, bag number, number of bags from that netWeigh bags in kilograms. Record.Note if fish were kept for sex determination, length – weight or scales and the number kept.Sex ratioUse Sex sheetRandomly select 2 nets. Sample 50 fish from each net.Record date and net numberWeigh two empty buckets and record weight.Separate fish by sex. Try not to squeeze out eggs/sperm.Count number of males and females. Record.Weigh buckets with males or females in them. Record.Length WeightUse Length Weight sheetSelect a random net and sample 30 fish from itRecord date, net number, if fish were frozenRecord length, weight and sex.Compare to scale sheet. Collect scale sample if category is not filled. Pull scales from behind the dorsal fin. Note on data sheet that scales were taken. Scale envelopes should have date, length, weight, net number and sex of fish on them.
Related Sites
Short Name
BIOSMLT1
Version Number
36
Subscribe to smelt removal

 

 

National Science Foundation | LTER Network | Center for Limnology        

This material is based upon work supported by the National Science Foundation under Cooperative Agreement #DEB-2025982, NTL LTER (ROR: 04gq8q482). Any opinions, findings, conclusions, or recommendations expressed in the material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation.