US Long-Term Ecological Research Network

North Temperate Lakes LTER: Fish Abundance 1981 - current

Abstract
This data set is a derived data set based on fish catch data. Data are collected annually to enable us to track the fish assemblages of eleven primary lakes (Allequash, Big Muskellunge, Crystal, Sparkling, Trout, bog lakes 27-02 [Crystal Bog] and 12-15 [Trout Bog], Mendota, Monona, Wingra and Fish). Sampling on Lakes Monona, Wingra, and Fish started in 1995; sampling on other lakes started in 1981. Sampling is done at six littoral zone sites per lake with seine, minnow or crayfish traps, and fyke nets; a boat-mounted electrofishing system samples three littoral transects. Vertically hung gill nets are used to obtain two pelagic samples per lake from the deepest point. A trammel net samples across the thermocline at two sites per lake. In the bog lakes only fyke nets and minnow traps are deployed. Parameters measured include species-level identification and lengths for all fish caught, and weight and scale samples from a subset. Derived data sets include species richness, catch per unit effort, and size distribution by species, lake, and year. Protocol used to generate data: Day seines were only used in 1981 and have been eliminated from this data set to make sampling effort across years comparable. Number caught for each species is summed over repetitions of a gear within a lake and over depth. For information on fish stocking by the Wisconsin Department of Natural Resources in LTER lakes in Dane and Vilas counties, see https://dnr.wi.gov/fisheriesmanagement/Public/Summary/Index The only sampling done in 2020 were a single gill-netting replicate in Sparkling, Crystal, and Trout lakes. Sampling in Fish Lake was suspended in 2021 due to significant lake level changes. Sampling Frequency: annually. Number of sites: 11
Core Areas
Dataset ID
7
Date Range
-
Maintenance
ongoing
Metadata Provider
Methods
The same sampling sites are used each year. All sampling occurs between the 3rd week of July and Labor Day. Sampling sites were chosen by random process in 1981 for the Northern lakes (Trout, Allequash, Sparkling, Crystal, and Big Muskellunge). Sites for Lake Mendota were chosen in 1981, and for the other Madison lakes (Monona, Fish, and Wingra) in 1995. All sites are identified with GPS coordinates, except on the bog lakes (Trout Bog and Crystal Bog) where nets are placed equal distances apart around the entire circumference of the lake in approximately the same locations each year.

Night seining is conducted on 6 seine sites per lake, each consisting of 100 meters of shoreline. Prior to 1997 this was subdivided into 3 seine hauls, each covering 33 meters. In 1997, seine hauls were reduced to 2 hauls of 33m each. The final section of the site is used as an alternate seine site in the event of difficulty in one of the first two hauls.
The seine used is 12.2 m long by 1.2 m deep, consisting of two 5.5 x 1.2 m wings surrounding a 1.2 x 1.2 x 1.2 m central bag. The wings are made of 6.4 mm stretch measure knitted delta-strength nylon mesh, and the bag is of 3.2 mm delta strength nylon mesh. The entire net is tarred. The two wings and the opening to the bag have weighted foot ropes and buoyed head ropes. An 8m length of rope is tied between the seine poles as a guide for the maximum spread of the seine.

A trammel net is set at two sites in each lake, and fished for approximately 24 hours at each site. The net is set on the bottom, along a line perpendicular to the shoreline and crossing the thermocline, with the shallow end at about 3m depth,. The trammel net used is 30.5 m long and 1.1 m deep. It consists of two outer nets of 170 mm square 32 kg test mesh multifilament nylon with an inner panel of 51 mm stretch mesh 9 kg test multifilament nylon. The three nets are connected at the leaded foot line and the buoyed head rope.

Fyke nets are deployed at six littoral sampling sites in each lake, and fished for approximately 24 hours. In Crystal Bog and Trout Bog lakes the fyke nets are suspended by placing floats on the hoops and frames to prevent the nets from sinking into the sediments. For the northern lakes, each fyke net is approximately 12 m long and consists of two rectangular steel frames 90 cm wide by 75 cm high and 4 steel hoops, all covered by 7 mm delta stretch mesh nylon netting. An 8 m long by 1.25 m deep leader net made of 7 mm delta stretch mesh nylon netting is attached to a center bar of the first rectangular frame (net mouth). The second rectangular frame has two 10 cm wide by 70 cm high openings, one on each side of the frame center bar. The four hoops follow the second frame. Throats 10 cm in diameter are located between the second and third hoops. The net ends in a bag with a 20.4 cm opening at the end, which is tied shut while the net is fishing. New nets of the same dimensions were purchased for the Northern Highland lakes in 2000. Fyke nets for the Madison lakes are 10 m long (including lead) with 1 rectangular aluminum frame followed by 2 aluminum hoops. The aluminum frame is 98 cm wide x 82 cm tall, and is constructed of 2.5 cm tubing, with an additional center vertical bar. The hoops are 60 cm in diameter and constructed of 5 mm diameter aluminum rod. The single net funnel is between the first and second hoops and is 20 cm in diameter. The lead is 8 m long and 1.25m deep, constructed from 7mm delta stretch mesh.

Crayfish traps are set on all lakes except the bog lakes (Crystal Bog and Trout Bog). Minnow traps are set only on the bog lakes. Prior to 1998, five traps were set at each fyke net site. Beginning 1998, three traps are set per site. Minnow traps and crayfish traps are set in shallow water (approx 1 m), 2 traps on one side, and 1 trap on the other side of the fyke net lead. Minnow traps are baited with 1 slice of bread, and crayfish traps with 120 g of beef liver. Traps are fished for approximately 24 hours. Crayfish are identified to species. Minnows caught in either crayfish or minnow traps are identified to species, and measured for total length. Minnow traps are galvanized steel two piece traps, 44.5 cm long by 30.5 cm maximum diameter with 2.5 cm diameter openings at the ends. The mesh size is 6.4 mm on a side. Crayfish traps are identical, but the opening hole of both sides of the trap has been forced to 5 to 7 cm. Crayfish sampling was terminated for the southern lakes in 2004 after it was determined that the catch per unit effort was too low (2 crayfish caught in 500+ traps)

Gill nets are set at the deepest point of all LTER lakes except Crystal Bog, Trout Bog, and Fish Lake. The nets are set for two consecutive 24 hour sets. The gill nets are a set of 7 nets, each in a different mesh size, hung vertically on foam rollers from the surface to the bottom of the lake, and chained together in a line. Each net is 4 m wide and 33 m long. From 1981 through 1990 the nets were multifilament mesh, in stretched mesh sizes of 19, 25, 32, 38, 51, 64, and 89 mm. In 1991, the multifilament nets were replaced with monofilament nets of the same sizes. Stretcher bars are installed at 10 meter intervals from the bottom to keep the net as rectangular as possible when deployed.

A boom style electrofishing system is used to sample the littoral zone fish community. Prior to 1997, four electrofishing transects were done on each lake. In 1997, the number of transects was reduced to 3. The same transects are used each year. Each transect consists of 30 minutes of current output, with the boat moving parallel to shore in 1-2 meters of water at a slow steady speed. We use the DC pulse system, with 240 volts at 3-5 amps. Transect lengths vary depending upon the size of the lake. If the end of a transect is reached before 30 minutes has elapsed, time is paused while the electrofisher loops back to the start of the transect. The transect is then repeated for the remaining time.

For all collecting methods, the fish are processed as follows. Each individual fish is identified to species. The total length of the fish is measured in mm, from nose to pinched tail. Prior to 1997, the weight of the first five fish of each species in each 10 mm size category was also measured, using Pesola spring balances. Starting in 1997, two fish are weighed for each species in each 5mm size category. A scale sample is collected from each yellow perch, rock bass, and cisco that is weighed. For gill net catches, the depth at which each individual is caught is also recorded.

Protocol Log. 1983: Discontinued fyke nets and trammel nets on Lake Mendota until 1995. 1984: Discontinued crayfish on Lake Mendota until 1995. Only gillnet and seines on Lake Mendota.1995: Resumed sampling Lake Mendota with the full suite of sampling gear. 1995: Began sampling Lakes Wingra, Monona, and Fish. 1997: Two fish are weighed for each fish species in each 5mm size category. Previously, five fish were weighed for each fish species in each 10mm size category. 1997: Data recording switched from manual field sheets to an electronic system. 1997: Changed from 4 to 3 electrofishing runs per lake. 1997: Changed from 18 to 12 seine hauls per lake. 1998: Changed from 30 to 18 crayfish or minnow traps per lake. 2004: Discontinued crayfish or minnow traps on southern lakes. 2020: Fish sampling very limited due to pandemic. 2021 discontinued all night seining.

DATA MODIFICATIONS
Prior to 2018, gill net data had been standardized to a 24-hour sampling period. This is no longer the case, and catch numbers for all years have been recomputed to reflect the number of fish actually caught.
2018-01-18: Species names ('spname') added in 2012 had space characters appended to the end of the name. These spaces have been removed. The occasional appearance throughout the data set of species name 'SUNFISH' and 'LARVALSUNFISH' have all been changed to 'UNIDSUNFISH'.
Short Name
NTLFI02
Version Number
41

Landscape Position Project at North Temperate Lakes LTER: Fish 1998 - 1999

Abstract
As part of the Landscape Position Project, we conducted fish sampling on each of 26 lakes using a variety of gear types. Sampling was conducted beginning in the 3rd week in June and running through the endof July in 1998. In 1999, sampling was conducted from early July through August. We used vertical gillnets of various mesh sizes (19, 32, 51, 64, 89-mm stretch mesh) to sample pelagic fishes. The nets were fished in the deep basin of each lake for one diel cycle. We used fyke nets to sample fishes in the shallow near shore areas. Three nets were set, one each at differing locations defined by substrate type (muck, sand and cobble) for one diel cycle. Three crayfish traps were set along side each of the fyke nets. We performed electrofishing over two, 30 minute transects along the near shore area between 0.3 and 1.5-m in depth. Our goal was to capture, identify and measure as many game and non-game fish species as possible Sampling Frequency: one survey on each lake in late June through August of 1998 or 1999 Number of sites: 26
Core Areas
Dataset ID
100
Date Range
-
LTER Keywords
Maintenance
completed
Metadata Provider
Methods
Fish SamplingFish sampling was conducted on each lake at least one month after thermal stratification had taken place, beginning on the 3rd week in June and running through the 3rd week in July. This was done to minimize the effects of winter stress and spawning on fish weight given their length. Several gears were employed to estimate fish diversity in each lake, each being effective at catching a different set of fishes.Vertical gillnets were employed to sample pelagic fishes. A spectrum of mesh sizes (19, 32, 51, 64, 89-mm stretch mesh) were used, with each mesh size effectively catching a different size range of fish. The nets were fished in the deep basin of each lake for one diel cycle.Fyke nets were employed to sample fishes in the shallow near shore areas. Mini fyke nets with a mouth opening 0.75-m high by 1.25-m wide constructed with 4-mm delta mesh, with a 1-m by 5-m single lead were set so as the lead ran perpendicular from shore and that the mouth sat in approximately 1-m of water. There were 3 nets set at differing locations defined by substrate type (muck, sand and cobble) for one diel cycle. Three crayfish traps were set along side each of the fyke nets so as to sample the same habitat type sampled by each fyke net.Electrofishing occurred in the near shore area between 0.3 and 1.5-m in depth. Two 30 minute transects were performed such that a variety of substrate types were sampled. The dipnets used to net fish during electrofishing consisted of 4-mm delta mesh and were capable of retaining small fishes (down to 20-mm). Our goal was to capture and identify as many game and non-game fish species as possible.Fish ProcessingFish caught in each gear type were processed by measuring mass and total length of all fish of each species; however, a subset of each species was measured when the catch rate was high. Two fish in each 5-mm size class for each species were weighed and length measurements were taken so as to collect weight measurements for a wide size range of each species. If the catch of a given species in a given size class (small, medium or large) within a particular set or electro-shocking run exceeded 30 fish, 30 were measured for each species. Those not measured for length in each size class were counted and recorded so as to associate them with those that were measured to allow length frequency distributions to be generated while expediting our processing and avoiding redundant weight and length measuring. Each fish was identified to genus and species using the taxonomic key in Becker (1983). Any game fish killed were turned over to the appropriate Department of Natural Resource Game Warden.
Short Name
LPPFISH1
Version Number
9

Biocomplexity at North Temperate Lakes LTER; Coordinated Field Studies: Fish / Crayfish Abundance 2001 - 2004

Abstract
Abundance data for fish and crayfish collected for Biocomplexity Project; Landscape Context - Coordinated Field Studies http://infotrek.er.usgs.gov/doc/wdnr_biology/Public_Stocking/StateMapHotspotsAllYears.htm - Infomation on fish stocking by Wisconsin Department of Natural Resouces in Biocomplexity Lakes. Sampling Frequency: annually Number of sites: 58
Core Areas
Dataset ID
84
Date Range
-
Maintenance
completed
Metadata Provider
Methods
Littoral Zone Surveys: Littoral habitat, fish and macrophyte surveys were performed at eight sites within each of the 55 lakes. The sites were chosen by randomly selecting two points per compass quadrant of each lake. Each year littoral habitat surveys were conducted in June, fish surveys in July and macrophyte surveys in August.Littoral fish were sampled in July of each year, along the shallow areas (water depth greater than 0 and less than2 m) adjacent to the riparian plots. Night electroshocking and crayfish and minnow traps were used to catch fish and crayfish. All species were identified and counted.
Short Name
BIOFISH2
Version Number
8
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