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VDGIF Report for Lake Anna

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  • VDGIF Report for Lake Anna

    Was talking with John Odenkirk at VDGIF yesterday and he forwarded me this info on Lake Anna. While we may not be catching many fish......they obviously are there and are doing very well.
    Lake Anna
     Standardized spring electrofishing (EF) samples were conducted three consecutive days at the end of April,
    2018 at portions of the upper, middle and lower lake routinely sampled annually for the past 25 years.
     Largemouth Bass (LMB) 2018 EF catch rates (fish/hr., or CPE) were above 90% confidence limits for all
    size categories. Mean CPEs were: 12 (fingerlings; fish <200 mm), 81 (stock; fish >200 mm), 57 (quality;
    fish >300 mm), 31 (preferred; fish >380 mm), 4 (memorable; fish > 510 mm), and 93 (total; all bass).
    These are considered excellent catch rates for LMB in a large impoundment, and many of these CPEs were
    near all-time highs.
     LMB structural indices based on EF were average based on period of record. PSD was 71, and RSD-P was
    38 suggesting a sample and population size structure of larger fish. PSD has remained remarkably
    consistent over a quarter century with a CV of only 9%. Stable water levels, consistent recruitment and
    quality habitat are believed to have facilitated this trend.
     Gill net (GN) sampling was conducted in November and December, 2018 at 18 randomly selected sites and
    resulted in the capture of 1,946 fish representing 21 species and one hybrid. Overall, catch rates (fish/net
    night or CPE) were down compared to long-term averages; however, dramatic patterns were noted including
    record low catches of some species and near record highs of others. The wettest year in recorded history
    combined with below-average water temperatures during sampling may have played a role in anomalous
    catch rates.
     GN catch rate of Gizzard Shad (GZS) (2.2/net night NN) was below 90% confidence limits (CL) and an all-
    time low for the period of record (22 years). Length frequency analysis revealed a bi-modal distribution
    with peaks around 110 and 290 mm TL. Low GZS CPE is cause for continued moderate concern given
    their primary contribution to the clupeid forage base supporting pelagic predator stockings.
     Threadfin Shad (THS) and Blueback Herring (BLH) catch rates (12.5/NN and 7.1/NN) were above 90% CL
    and near all-time highs. These two forage species had, by far, the highest catch variation of any species
    sampled – CVs ranged from 102 – 150% (compared with GZS at 54%).
     GN catch rate of Striped Bass (STB) (2.1/NN) was below 90% confidence limits. However, hybrid Striped
    Bass (HSB) were stocked in 2014 and 2017; and HSB were caught at a rate of 0.5/NN resulting in a
    combined Morone CPE of 2.6/NN (which was still well below average).
     The dominance and persistence of the 2012 STB year class (YC) stocked at 31/ac was noted for the fifth
    consecutive year, as age-6 fish produced the second highest catch curve residual of the sample.
    Relationships between stocking rates and GN catch were greatly strengthened in 2017, as logged catch rate
    of age-0 (r 2 =0.90; P=0.03), age-1 (lagged one year; r 2 =0.93; P=0.006), and age-2 (lagged two years r 2 =0.89;
    P=0.055) increased substantially and suggested all cohorts were fully recruited to the gear. It now appears
    that about 90% of recruitment is driven by stocking rate (typically 3 or 4 locations/ramps are used annually),
    and year classes are persistent.
     Fishing success for STB in 2019 may be below average, as the weak 2014 and 2015 YC work through the
    window of typical harvest. However, fish from the 2012 and 2013 YC should provide above average
    chances for larger fish (albeit fewer overall). Sub-legal fish should be abundant in 2019 as the dominant
    2017 YC nears full recruitment.
     STB was slow compared to other reservoir populations in Virginia and throughout the southeast U.S. Mean
    length-at-age in 2018 for fish age 0-3 was 229, 363, 474, and 516 mm TL which represented declines from
    2017.

     Hybrid striped bass (HSB) growth was acceptable, as age-1+ fish (2017 YC) averaged 342mm (range 276-
    394). No HSB from the 2014 YC were caught.
     Striped bass cohort based mortality estimates were relatively low. Estimates were calculated for nine year
    classes with adequate data for fish aged 0-5 (6 samples per regression), and eight regressions were
    significant. Total annual mortality (TAM) ranged from 24-40% and averaged 34% in 2017. A catch curve
    of 2018 data produced similar TAM of 27%.
     Gill net catch rate of Black Crappie (BLC) was 9.4.NN which was greater than in 2017, above average, but
    within 90% CI. BLC size structure was again good in 2018 - there were 17 fish collected over 305 mm.
     Gill net catch rate of saugeye was again zero after declining for three consecutive years (0.3/NN in 2017,
    0.4/NN in 2016, and 0.7/NN in 2015), and it appears likely fish from this experimental stocking in 2013 are
    nearly gone.
    Management Recommendations
     Continue standardized annual sampling including spring EF at three locations for 3 runs of 2000 seconds
    each (upper, middle and lower) and stratified random gill netting with 200’ multipanel nets (36 net nights
    total).
     Establish a standard annual Morone stocking rate to include 10 STB and 10 HSB per acre (96,000 each).
    Stocking rates may be adjusted slightly based on forage samples (primarily GZS abundance).
     Investigate the potential to stock saugeye periodically (e.g., every third year given adequate forage base) to
    diversify the fishery. Request saugeye at 10 per acre in 2020.
    2013 Frog Only Tournament Winner
    2010 Tie for VA-Outdoors Angler of the Year
    2009 Caroline County Rotary Club Tournament Winner
    2007 Tuesday Night Classic Champions
    "Many men go fishing all of their lives without knowing that it is not fish they are after."
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  • #2
    good read, thanks for the info.
    Make VAO Great again

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    • #3
      I was a volunteer on Odenkirk’s boat for both of those studies last year on LKA. Got to see first hand how well the fishery is doing and how they manage the LAKE. Hats off to John and VDGIF!!

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      • #4
        I wouldn't mind some saugeye in Anna either....

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        • #5
          Nice thread,i like it

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