LOUISIANA DEPARTMENT OF

WILDLIFE & FISHERIES

OFFICE OF FISHERIES

INLAND FISHERIES DIVISION

PART VI -B

WATERBODY MANAGEMENT PLAN SERIES

Larto-Saline Complex

WATERBODY EVALUATION &

RECOMMENDATIONS

2

CHRONOLOGY

March 18, 2010 - Prepared by

Richard D Moses, Biologist Manager, District 3

Richard McGuffee, Biologist Supervisor, District 3

December 1, 2014 – Updated by

Richard Moses, Biologist Manager, District 3

Shelby Richard, Biologist II, District 3

March 2018 – Revised by

Richard McGuffee, Biologist Manager, District 3

Shelby Richard, Biologist Supervisor, District 3

The remainder of the page intentionally left blank.

3

TABLE OF CONTENTS

WATERBODY EVALUATION ................................................................................................................................. 4

STRATEGY STATEMENT ................................................................................................................................... 4 Recreational........................................................................................................................................................... 4 Commercial ........................................................................................................................................................... 4 Species of Special Concern .................................................................................................................................... 4

EXISTING HARVEST REGULATIONS ............................................................................................................. 4 Recreational........................................................................................................................................................... 4 Commercial ........................................................................................................................................................... 4

SPECIES EVALUATION ....................................................................................................................................... 4 Recreational........................................................................................................................................................... 4 Commercial ......................................................................................................................................................... 16 Creel Survey ........................................................................................................................................................ 17

HABITAT EVALUATION ................................................................................................................................... 20 Substrate .............................................................................................................................................................. 21 Artificial Structure ............................................................................................................................................... 21

CONDITION IMBALANCE / PROBLEM ......................................................................................................... 21 CORRECTIVE ACTION NEEDED .................................................................................................................... 21

RECOMMENDATIONS .......................................................................................................................................... 22

APPENDIX I .............................................................................................................................................................. 23

APPENDIX II ............................................................................................................................................................ 24

4

WATERBODY EVALUATION

STRATEGY STATEMENT

Recreational

Sportfish species, primarily largemouth bass (LMB) and crappie, are managed to provide a

sustainable population while providing anglers the opportunity to catch or harvest adequate

numbers of fish to maintain angler interest and efforts.

Commercial

Commercial fishing is minimal in the Larto-Saline Complex. Water control measures over the

past 40 years have altered water flow patterns and fisheries habitat in such a manner that the

Larto-Saline Complex does not support high numbers of commercial species. A strategy

directed specifically to the commercial fishery is not applied.

Species of Special Concern

No threatened or endangered fish species are known to inhabit this waterbody.

EXISTING HARVEST REGULATIONS

Recreational

This water body is managed under statewide regulations for all fish species. The Louisiana

Department of Wildlife and Fisheries recreational fishing regulations may be viewed at the

link below:

http://www.wlf.louisiana.gov/regulations

Commercial

The LDWF commercial fishing regulations may be viewed at the link below:

http://www.wlf.louisiana.gov/regulations

SPECIES EVALUATION

Recreational

Largemouth Bass

Largemouth bass populations are targeted for assessment because they are a species indicative

of the overall health of the fish population due to their high position in the food chain.

Electrofishing is the most efficient sampling method for collecting largemouth bass to evaluate

abundance and size distribution.

Relative abundance and size structure indices

Electrofishing has been used to collect largemouth bass population data in the Larto-Saline

Complex since the fall of 1989. Catch-per-unit-effort (CPUE) from spring and fall

5

0

25

50

75

100

125

1992 2000 2001 2006 2009

Nu

mb

er

Pe

r H

ou

r

electrofishing are used as indicators of LMB relative abundance. Spring electrofishing results

show a relatively stable average CPUE for the sampling period 1992 through 2009 (Figure 1).

The significant increase in CPUE observed in 2000 can likely be attributed to a drought that

caused low water levels at the time of sampling. Low water levels force LMB to congregate

in areas accessible to electrofishing methods. Fall electrofishing from 1989 through 2010 also

indicated a relatively stable CPUE average (Figure 2). Fall samples from 2015-2017 had a

significant increase in CPUE. These observed variations are likely due to increased spawning

and nursery habitat from the 2014 drawdown and high water events. Significant variable

annual recruitment is typical for sub-stock catch rates. Sub-stock and stock-size LMB CPUE

from fall 2015, 2016, and 2017 indicates that the 2014 drawdown and high water increased

spawning success and recruitment in those years (Figures 3 and 4).

Figure 1. Average CPUE (± SE) for largemouth bass collected during spring electrofishing

from Larto-Saline Complex, Louisiana from 1992 – 2009.

6

0

25

50

75

100

125

150

175

200

225

250N

um

be

r P

er

Ho

ur

YEAR

Figure 2. Average CPUE (± SE) for largemouth bass collected during fall electrofishing from

Larto-Saline Complex, Louisiana from 1989-2017.

Figure 3. The average CPUE for largemouth bass by size class collected from Larto-Saline

Complex, Louisiana during spring electrofishing from 1992 – 2009.

0

25

50

75

1992 2000 2001 2006 2009

Nu

mb

er

Pe

r H

ou

r

YEAR

Sub-Stock (<8") Stock (8"-12")

Quality (12"-15") Preferred (15"-20")

Memorable and Greater (>20")

7

Figure 4. The average CPUE for largemouth bass by size class collected from Larto-Saline

Complex, Louisiana during fall electrofishing from 1989 – 2017.

Proportional stock density (PSD) and relative stock density (RSD) are indices used to

numerically describe length-frequency data (Figures 5 and 6). Proportional stock density

compares the number of fish of quality size (greater than 12 inches for largemouth bass) to the

number of bass of stock size (8 inches in length). PSD is expressed as a percent. A fish

population with a high PSD consists mainly of larger individuals, whereas a population with a

low PSD consists mainly of smaller fish. For example, Figure 5 below indicates a PSD of 41

for 2006. The number indicates that 41% of the bass stock (fish over 8 inches) in the sample

was at least 12 inches or longer. Individual lakes vary widely in their ability to support

populations of bass. PSD values between 40 and 60 are considered to be satisfactory.

Number of bass>12 inches

PSD = ———————————— x100

Number of bass>8 inches

Relative stock density (RSD) is the proportion of largemouth bass in a stock (fish over 8

inches) that are 15 inches or longer.

Number of bass>15 inches

RSD = ———————————— x100

Number of bass>8 inches

0

25

50

75

100

125

150

175

1989 1990 1991 1992 1999 2000 2001 2003 2006 2010 2015 2016 2017

Nu

mb

er

Pe

r H

ou

r

YEAR

Sub-Stock (<8") Stock (8"-12")

Quality (12"-15") Preferred (15"-20")

Memorable and Greater (>20")

8

Figure 5. PSD and RSD-p for largemouth bass collected from Larto-Saline Complex,

Louisiana during spring electrofishing from 1992 – 2009.

Trends in sampling data indicate PSD and RSD-p values have increased from 1992 through

2009. This is likely the result of an increased level of complex cover during that time. Hydrilla

became established in the lake in the early 2000’s. Hydrilla coverage fluctuates depending on

the influence of water level fluctuation. Submersed vegetation is present throughout the lake

in shallow water areas. PSD and RSD-p values based on fall electrofishing results have

gradually declined from all-time highs in 2010 (71 and 35%, respectively), to 40% and 10%,

respectively in 2017 (Figure 6). The 2017 values are still considered satisfactory for a balanced

largemouth bass population.

0

10

20

30

40

50

60

70

1992 2000 2001 2006 2009

Pe

rce

nta

ge

Year

PSD RSD

9

Figure 6. PSD and RSD-p for largemouth bass collected from Larto-Saline Complex,

Louisiana during fall electrofishing from 1989 – 2017.

Forage

Abundances of shad and sunfishes are the primary forage of largemouth bass in the Larto-

Saline Complex. Crawfish are plentiful as well due to the regular occurrence of back water

flooding. Forage availability is measured by shoreline seine sampling (Figure 7) and by

electrofishing sampling (Figure 8).

Forage availability is also measured indirectly through measurement of LMB body condition

or relative weight. Relative weight (Wr) is the ratio of a fish’s weight to the weight of a

“standard” fish of the same length. The index is calculated by dividing the weight of a fish by

the standard weight for its length, and multiplying the quotient by 100. Largemouth bass

relative weights below 80 indicate a potential problem with forage availability. Information

displayed in Figure 9 suggests the presence of sufficient forage each year. Relative weight

values ranged from 83 to 108 from 1989-2017.

0

10

20

30

40

50

60

70

80

1989 1990 1991 1992 1999 2000 2001 2003 2006 2010 2015 2016 2017

Pe

rce

nta

ge

Year

PSD RSD

10

Figure 7. The CPUE (average number of fish per seine haul) of all species collected from

shoreline seining for Larto-Saline Complex, LA, from 1990 – 2009.

Figure 8. Number per hour of Lepomis spp., Dorosoma spp., and all other species less than 6

inches TL captured in standardized fall forage samples on Larto-Saline Complex, LA, from

2003-2017.

0

100

200

300

400

500

1990 2000 2001 2006 2009

Ave

rage

Nu

mb

er

of

Fish

Pe

r H

aul

0

50

100

150

200

250

2003 2006 2017

Nu

mb

er

of

Ind

ivid

ual

s

Lepomis spp. Dorosoma spp. All Other Species

11

Figure 9. Relative weight values for stock-, quality-, and preferred-size classes of

largemouth bass collected during fall electrofishing for Larto-Saline Complex, Louisiana

from 1989 – 2017.

Largemouth Bass Age and Growth

Age and growth data was collected in 1989-1990, 2006, and 2015-2017. A population

assessment was conducted in 2015-2017 on largemouth bass in the Larto-Saline Complex. The

age, growth and mortality results showed that the length-at-age is similar to the statewide

average until age 8, and within the 95% confidence interval (Figure 10). Ages 8-9 are below

the statewide average, but this is likely due to small sample sizes of that age class. Larto-Saline

Complex LMB growth rates are compared in Table 1. The maximum LMB length observed in

the most recent (2015-2017) Larto-Saline Complex assessment was 20 inches TL and the

maximum age recorded was 9 years.

0

25

50

75

100

125

1989 1990 1991 1992 1999 2000 2001 2003 2006 2010 2015 2016 2017

Re

lati

ve W

eigh

t

Stock Quality Preferred

12

Table 1. Mean length at capture by age for Largemouth bass in 1989-90, 2006, and 2015-17

for Larto-Saline Complex, Louisiana.

AGE 1989-1990

(N=87)

2006

(N=99)

2015

(N=168)

2016

(N=134)

2017

(N=136)

0 - 6.7 6.7 6.1 6.6

1 10.1 11.5 9.9 9.3 9.1

2 12.7 14.3 13.0 14.0 13.0

3 15.5 16.0 15.8 16.5 15.9

4 - 16.4 16.5 18.0 16.8

5 - 17.5 18.2 17.6 17.4

6 - 20.2 18.6 18.3 18.2

7 - - 19.3 - -

8 - - 18.4 20.2 -

9 - - 18.4 - -

Figure 10. Mean length-at-capture by age class for largemouth bass collected during fall

electrofishing samples for the years 2015-2017 from Larto-Saline Complex, LA (n=437).

Error bars represent 95% confidence intervals.

0

5

10

15

20

25

0 1 2 3 4 5 6 7 8 9

Inch

es

Age Class

Statewide Average 2009-2017 Larto-Saline 2015-2017

13

Largemouth bass genetics

Electrophoretic (Isozyme) analysis of liver tissue was used to determine the percent of the

Florida largemouth bass (FLMB) genome present in the Larto-Saline complex. Florida

largemouth bass were not introduced into the Larto-Saline Complex by LDWF until 2015.

Prior to stocking, analysis showed that the Larto-Saline Complex LMB population did contain

a 12.1% Florida X northern hybrids in 2006. The introduction of FLMB likely occurred during

a high water event, since FLMB have been stocked into the Red River and other Louisiana

waterbodies. LDWF stocked approximately 250,339 FLMB into the complex from 2015-2017.

See Table 2 for a complete summary of genetic testing.

Table 2. Largemouth bass genetic testing results from Larto-Saline Complex, Louisiana.

Year % Northern % Florida % Hybrid % Florida Influence

2006 87.9 (n=87) 0 12.1 (n=12) 12.1

2015 100 (n=170) 0 0 0

2016 99.3 (n=143) 0.7 (n=1) 0 0.7

2017 91.1 (n=124) 1.5 (n=2) 7.4 (n=10) 8.9

Crappie

Crappie fishing in the Larto-Saline Complex is considered to be outstanding. Both black

crappie (Pomoxis nigromaculatus) and white crappie (P. annularis) occur in the complex. The

dynamic nature of crappie populations includes considerable variance over time. Levels of

angler satisfaction are typically proportional to crappie population trends and therefore, also

tend to be cyclic.

Crappie were sampled with electrofishing gear from 1999-2010. The sample catch rate was

variable, ranging between 0 and 65 fish per hour average (Figure 11 and 12). The technique

of sampling crappie with lead nets has become a standardized sampling method for LDWF.

Lead nets were effectively used to sample the crappie population from 2009 – 2012 (Figure

13). These results show an equal abundance and size distribution in population between both

species of crappie (Table 3 and Figure 14).

A crappie population assessment study was conducted from 2010 – 2012. Analysis indicates

that crappie in the Larto-Saline Complex had the second lowest growth rate when compared

to eight other lakes that were sampled during this same time period, and reached a preferred-

size class (10-inch TL) in 2.95 years on average (Appendix PROJECT, Table 3). Because the

majority of the fish sampled for age and growth were captured by lead nets, age 0+ crappies

are represented minimally due to this gear’s size selectivity. Crappie growth rate results can be

found in Table 4.

14

Figure 11. Average CPUE for crappie collected during fall electrofishing from Larto-Saline

Complex, Louisiana from 1989-2010.

Figure 12. Average CPUE for crappie collected during spring electrofishing from Larto-

Saline Complex, Louisiana from 2000-2009.

0

10

20

30

40

50

60

70

1989 1990 1991 1999 2000 2001 2003 2006 2010

Ave

rage

CP

UE

White Crappie Black Crappie

0

5

10

15

20

25

30

2000 2001 2006 2009

Ave

rage

CP

UE

White Crappie Black Crappie

15

Figure 13. Average CPUE for crappie generated from standardized lead net results 2009-

2012.

Figure 14. Black crappie (n=834) and white crappie (n=806) size distributions (inch

groups) on Larto-Saline Lake, LA, generated from standardized lead net results 2009-

2012.

0

50

100

150

200

250

3 4 5 6 7 8 9 10 11 12 13 14 15

Nu

mb

er

White Crappie Black Crappie

0

0.1

0.2

0.3

0.4

0.5

0.6

2009 2010 2011 2012

Ave

rage

CP

UE

White Crappie Black Crappie

16

Table 3. The contribution of black and white crappies to total crappie catch by year for

Larto-Saline Complex, LA, fall lead net surveys 2009-2012.

Year Black Crappie White Crappie Total

2009 5 (7%) 69 (93%) 74

2010 61 (14%) 366 (86%) 427

2011 320 (70%) 135 (30%) 455

2012 448 (65%) 236 (35%) 684

Total 834 (51%) 806 (49%) 1640

Table 4. Length at capture by age by species of crappie captured in 2011-2012 for Larto-

Saline Complex, Louisiana.

Age

2011

Black

Crappie

(N=48)

2012

Black

Crappie

(N=104)

2011

White

Crappie

(N=57)

2012 White

Crappie

(N=107)

0 - - - -

1 8.7 6.9 6.7 7.1

2 8.0 8.9 10.4 10.7

3 9.5 10.2 11.4 12.3

4 10.4 11.4 - 12.8

5 - - 13.0 -

6 - - 12.8 -

Commercial

Large rough fish species that comprise a commercial fishery are not found in sufficient

numbers to support a viable commercial fishery in the Larto-Saline Lake complex. However,

periodic backwater flooding of the Black and Red Rivers creates habitat to support a wide

variety of commercial species. Commercial harvest of these species is allowed in accordance

with statewide regulations. Wire traps, jug lines, trotlines and rod and reel are used to catch

commercial fish. Standardized biomass sampling (rotenone) conducted in 1998 showed the

most abundant commercial fish to be channel catfish followed by freshwater drum.

17

Figure 15. Biomass sampling results for commercial species for Larto-Saline Complex,

Louisiana in 1998.

Creel Survey

Angler creel surveys were conducted on Larto-Saline Complex in 2000, 2001, and 2015 to

gather data on recreational fishing efforts and harvest.

Largemouth bass anglers

Creel results show that 505 LMB anglers were interviewed. Catch rates improved from 1.66

(2000) LMB caught per angler trip to 3.45 (2015) LMB caught per angler trip. The retention

rates were between 48.87% and 68.1% (Table 5). Harvested sub-stock-sized LMB decreased

from 2000 to 2015, while quality-sized LMB increased in 2015 (Figure 16). The most

frequently harvested size groups were 11-13 inches TL (Figure 17).

Crappie anglers

Crappie creel results show that 637 crappie anglers were interviewed. Crappie catch per angler

trip decreased in 2015 (Table 5). This decreased catch per angler can be attributed to high water

events that allowed crappie to move into heavily woody and vegetated areas that anglers could

not reach. Harvested crappie size class results indicate a normal distribution with an increase

in harvested memorable size crappie in 2015 (Figure 18). Angler harvested inch groups ranged

from 8-10 inches TL (Figure 19).

0

20

40

60

80

100

120

1998

Po

un

ds

per

Acr

eFresh water drum

Big mouth Buffalo

Small mouth Buffalo

Flathead Catfish

Channel Catfish

Blue Catfish

18

Table 5. Largemouth bass and crappie creel results from Larto-Saline Complex, LA 2000,

2001, and 2015.

Year Total

Interviews

LMB

Anglers

Interviewed

LMB

Catch Per

Angler

Trip

LMB

Retention

Rate

Crappie

Anglers

Interviewed

Crappie

Catch Per

Angler

Trip

2000 382 191 1.66 68.10% 243 7.86

2001 274 84 2.97 48.87% 204 11.09

2015 374 230 3.45 59.09% 190 5.22

Figure 16. Number of largemouth bass harvested by size class from creel surveys

conducted in 2000, 2001, and 2015 on Larto-Saline Complex, LA.

0

10

20

30

40

50

60

2000 2001 2015

Nu

mb

er

Sub-Stock (<8") Stock (8"-12") Quality (12"-15") Preferred (15"-20") Memorable (>20")

19

Figure 17. Size distribution (inch groups) of angler harvested largemouth bass from Larto-

Saline Complex, LA creels 2000, 2001, 2015.

Figure 18. Crappie angler harvest percentage by size class from creel surveys conducted in

2000, 2001, and 2015 on Larto-Saline Complex, LA.

0

10

20

30

40

50

60

70

80

8 9 10 11 12 13 14 15 16 17 18 19 20 21

Nu

mb

er

LMB 2000 LMB 2001 LMB 2015

0

10

20

30

40

50

60

2000 2001 2015

Per

cen

tage

Sub-Stock (<5") Stock (5"-8") Quality (8"-10") Preferred (10"-12") Memorable (>12")

20

Figure 19. Size distribution (inch groups) of angler harvested crappie from Larto-Saline

Complex, LA, creels surveys conducted in 2000, 2001, 2015.

HABITAT EVALUATION

Aquatic Vegetation

A vegetation survey was conducted on July 19th and 25th and completed on August 1st of

2017. There was very little submersed vegetation observed. The submersed vegetation

present was hydrilla, coontail, fanwort and bladderwort, and comprise a total of

approximately 150 acres. Emergent vegetation present was American lotus, primrose,

and alligator weed. The majority of the lotus was located on the fringes of various bayous

and the Saline Lake area. Shad lake, which typically has large amounts of lotus, had very

little at this time. There was approximately 800 acres of American lotus present

throughout the Complex. Primrose and alligator weed were present on the fringes of

various bayous and lakes. There was approximately 100 acres of primrose and alligator

weed combined. The major floating plants observed were common and giant salvinia.

Common salvinia was observed sporadically throughout the complex. The majority of the

common salvinia was observed in the Shad Lake area. There was approximately 400

acres of common salvinia. Giant salvinia was observed in Big Creek, Little Saline, Saline

Lake and all connecting bayous of Little Saline and Saline Lake. No giant salvinia was

observed east of Saline Lake. There was approximately 800 acres of giant salvinia present.

0

50

100

150

200

250

300

350

400

450

500

4 5 6 7 8 9 10 11 12 13 14 15 16 17 18

Nu

mb

er

Crappie 2000 Crappie 2001 Crappie 2015

21

The 2018 estimates of aquatic vegetation are expected to remain similar to 2017, with the

exception of giant salvinia. If the lake receives a high water event, giant salvinia will

most likely spread throughout the complex. Even without a high water event, giant

salvinia will continue to expand into the adjacent bayous and lakes due to current, wind,

and boat traffic.

Substrate

The frequent water level fluctuation that occurs in the Larto-Saline Complex promotes

increased decomposition of organic substrate composition. The process improves the

suitability of the substrate for nesting sport fish species. The majority of the shoreline area is

wooded. This creates good buffer zones and helps reduce sedimentation. Areas in close

proximity to Red River backwater inflow have an accumulation of silt.

Artificial Structure

The physical characteristics of the Larto-Saline Complex include an abundance of complex

cover including aquatic vegetation, standing trees, stumps, logs, and button bush. No

additional complex cover is necessary.

CONDITION IMBALANCE / PROBLEM

Since construction of the Catahoula Lake Diversion Canal in 1972, there have been numerous

failures of the spoil bank. Related consequences have included an uncontrolled hydrological

connection between the Larto-Saline Complex and the diversion canal. Despite the recent

replacement of the problematic Cross Bayou Weir, the potential for spoil bank failures at other

locations will remain.

CORRECTIVE ACTION NEEDED

Due to the introduction and establishment of giant salvinia into the complex, it will likely be

necessary to conduct more foliar spray activities, weevil stocking, and lake drawdowns in the

future.

There were several days of freezing temperatures and ice formation on the lake in the winter

of 2017-2018. The effectiveness of these events on reducing the amount of salvinia present

will need to be observed before deciding whether a drawdown needs to be conducted in 2018.

22

RECOMMENDATIONS

1. Continue LDWF standardized sampling to assess fisheries populations.

2. LDWF spray crews will continue treating emergent and floating vegetation as needed with

either glyphosate (0.75 gal/acre) or diquat (0.75 gal/acre) and an approved surfactant (0.25

gal/acre) in accordance with LDWF Aquatic Herbicide Application Procedures. A mixture

of diquat (0.25 gal/acre) and glyphosate (0.75 gal/acre) with Turbulence (or approved

equivalent, 0.25 gal/acre) surfactant may be applied to common and giant salvinia from

April 1 – October 31. Alligator weed will be controlled with imazapyr (0.5 gal/acre) in

undeveloped areas and with imazamox (0.5 gal/acre) near houses and developed shorelines.

Turbulence surfactant (0.25 gal/acre) will be used in conjunction with both of these

herbicides.

3. Continue aquatic vegetation surveys each summer to determine species composition and

area coverage.

4. Conduct 3’ drawdown if deemed necessary. If the decision is made that a drawdown is

necessary, it will be conducted under the following guidelines. The drawdown should be

initiated on the week of June 18, 2018. The target level for the 2018 drawdown will be 3’

below normal pool elevation. The timing and depth of the drawdown was selected to create

the longest drying period and still allow access to the lake for foliar spraying. The

drawdown gates will be closed no later than November 1, 2018. The LDWF staff will work

with DOTD personnel to operate the control gate to fluctuate the water level in an effort to

maintain the 3’ below pool drawdown level.

23

APPENDIX I Typemap Larto-Saline Lake vegetation survey conducted on July 24th and 25th of 2013.

24

APPENDIX II

LOUISIANA DEPARTMENT OF WILDLIFE & FISHERIES

OFFICE OF FISHERIES

INLAND FISHERIES AND

RESEARCH AND ASSESSMENT SECTIONS

Larto-Saline Lake Crappie:

Population Characteristics

Freshwater Report Series

Baton Rouge, Louisiana

2014

25

LOUISIANA CRAPPIE PROJECT

Larto-Saline Lake

Every fish population is the product of a unique set of influences, both natural and man-induced.

A thorough understanding of those influences and the corresponding population response is

essential to good fisheries management. As part of a statewide effort, the Louisiana Department

of Wildlife and Fisheries (LDWF) recently completed a study to describe the Larto-Saline Lake

black crappie and white crappie (crappie) populations. The project included data collection over

a four-year period from 2009 – 2012. Population dynamics including relative abundance,

spawning success, growth, body condition, mortality, and longevity were measured.

Leadnet fishing gear was used to collect crappie from Larto-Saline Lake each fall. Length and

weight measurements were recorded for each fish and ear bones (called otoliths) were removed

from approximately 28% of the sampled fish for age and growth analyses. Annual growth rings

on the otoliths provide an accurate measurement of fish age. Since both species of crappie are

managed under the same harvest regulations, size and age for all of the sample fish were

combined to generate estimates of average growth rate and longevity.

Figure 1 illustrates that Larto-Saline Lake supports a healthy crappie population with some

individual crappie reaching 15 inches. Five to 12-inch fish were observed in all four years of the

project. It is important to note that fall leadnet sampling typically does not include young-of-the-

year size crappies. However, the recurring presence of small 5 to 10 inch (age-1) crappie

indicates successful reproduction from the previous year.

26

Figure 1. Length distributions of crappie collected from Larto-Saline Lake during fall leadnet

surveys in 2009-2012. Sample sizes (n) are presented in each graphic.

Age structure of the complete leadnet sample (2009-2012) is shown in Figure 2. Eighty-eight

percent of the total sample was comprised of age-1 and age-2 crappies. While crappie up to 7

years of age were found, only a small percentage of Larto-Saline Lake crappie were 4 years and

older. Average age at length for Larto-Saline Lake crappie is provided in Table 1. Growth is

generally good through age-1, but then slows to only two inches or less in length per year.

Body condition for Larto-Saline Lake crappie can be described as good. Good physical

condition of crappie generally is the product of an adequate food supply that is readily available

to predation.

Larto-Saline Lake exhibited moderately stable recruitment of age-1 crappies during the four-year

study. Consistently favorable spawning conditions for crappie are attributed.

Figure 2. The age structure of Larto-Saline Lake crappies 2009 - 2012.

0

200

400

600

800

1000

1200

0 1 2 3 4 5 6 7

Tota

l Nu

mb

er

Sam

ple

d

Age (Years)

n = 1,640

27

Age in Years Length in Inches

2.02 8.0

2.95 10.0

4.46 12.0

Table 1. Average age at length for Larto-Saline Lake crappie.

The rate at which fish die each year is referred to as mortality. Mortality consists of two parts:

natural mortality (predation, disease) and fishing mortality (angler harvest and discard mortality).

Results of the study indicate that the total mortality rate for Larto-Saline Lake crappie is high

(81%) when compared to other recently sampled Louisiana lakes. The following example is

provided to illustrate the effect. At 81% mortality, if you start with 100 age-1 Larto-Saline Lake

crappie, 19 will remain alive by age-2, 4 by age-3 and less than one fish remaining by age-4.

The results of this study suggest that the Larto-Saline Lake crappie population has a total

mortality that is much more influenced by fishing mortality than by natural factors (56% and

25%, respectively). The fishing mortality rate for Larto-Saline Lake crappie is 56% per year.

This rate comes from two sources; 1) harvest and 2) post release mortality.

Population simulations illustrating the effects of two theoretical size regulations were calculated.

Using the mortality rate (81%) determined for Larto-Saline Lake, anglers would be required to

release 70% of fish caught with a 10” minimum length limit (MLL). A 12” MLL would require

anglers to release 92% of their catch. These effects increase as the minimum size limit increases,

but are less pronounced with higher natural mortality scenarios. Length limit implementation

would also increase the mean weight of crappie harvested (64% for 10” MLL and 166% for 12”

MLL), however the lower number of crappie harvested would result in decreased overall yield (-

14% for 10” MLL and -61% for 12” MLL).

SUMMARY

It is important to note that crappie populations and their fisheries are not only influenced by

fishing effort, but also by anthropogenic and environmental factors. The type and degree of

human activity within watersheds, riparian zones, and specific waterbodies can affect crappie

populations by altering critical habitats. Additional factors influencing crappie populations

include aquatic vegetation coverage, water level management, and habitat improvements. The

frequency of floods, drought, and hurricanes can also influence crappie populations. While

consideration of these factors is important in effective fisheries management, evaluating how

these factors affect the Larto-Saline Lake crappie population and fishery is beyond the scope of

this report.

The Larto-Saline Lake crappie population is influenced by natural and fishing related mortalities

for a combined rate of 81%. If natural mortality remains constant, no increase in crappie yield

should be expected from the protection of a 10” or 12” minimum length limit. Moreover, the

required release rates associated with both minimum length limits (70% and 92% respectively)

would be poorly received by anglers that pursue crappie for food.

Size distribution, recruitment levels, and fish condition for the last three years of the study were

found to be at levels that indicate a stable and healthy Larto-Saline Lake crappie population. The

fishery is currently managed with no size restrictions and a 50 fish per day harvest limit. Given

the dynamics of the Larto-Saline Lake crappie population, no change in angler harvest regulation

is recommended.