1. No category

A Study of Texas Shrimp Populations
1974
A. W. Moffett
L. W. McEachron
ABSTRACT
Brown shrimp (Penaeus aztecus) were monitored in five coastal bays
during spring to predict the time of their bay-to-Gulf migration. The
Texas Parks and Wildlife Commission used the predicted late May or
early June onset of migration to set 1 June as the starting date of the
45-day closed season in the shallow Gulf, i.e., from the coast out to
18.53 km (10 nautical miles). The prediction was correct, and the
closed season allowed a portion of the brown shrimp population to reach
a large size before harvest.
Although the abundance of juvenile brown shrimp in the bays indi­
cated that stocks were adequate, brown shrimp landings of 16.1 million
kg (35.5 million lb) heads-off were poor. This may have been the result
of inflated operational costs that caused many shrimpers to remain in
port.
White shrimp (P. setiferus) were sampled to determine if bays
open to commercial shrimping contained an abundance of undersize shrimp
(over 65 headless to a pound) during the fall bay season (15 August 15 December). Sample analyses showed that 31.9% of white shrimp were
of legal size in Galveston Bay, 24,6% in Matagorda Bay and 33.9% in
Aransas Bay. Few white shrimp were of legal size in secondary bays of
the Galveston (5,2%) and Matagorda (1.7%) Bay systems.
Analysis of commercial catch data indicated that the brown shrimp
catch per 24 h fishing time off Galveston had decreased since 1968 while
total catch, although irregular, did not show this trend. Analysis of
white shrimp catch data from the same area suggested an increase in
catch per-unit-effort and catch since 1967.
The decline in the shrimp catch in Sabine Lake was accompanied
by a decrease in catch per-unit-effort. This decline was attributed
to large freshwater discharges into the lake and alteration of nursery
habitat. Shrimp catches from nearby Calcasieu Lake, Louisiana have
not declined. Shrimp catches from the Gulf off Sabine and Calcasieu
Lakes have not declined due to an increase in fishing effort.
INTRODUCTION
In 1974 Texas fishermen landed 16.1 million kg (35.5 million lb)
of brown shrimp worth $48.8 million, 5.2 million kg (11.3 million lb)
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of white shrimp worth $16.1 million and 0.6 million kg (1.3 million
lb) of pink shrimp worth $2.4 million.
Shrimp spawn in the Gulf of Mexico; the young are carried by
currents into bays. Within bays postlarval shrimp use salt marshes,
back bays and bayous as nursery grounds where they find ample food and
protection from predators among submerged vegetation. Shrimp of about
50 mm length leave the nursery areas and eventually migrate back to
Gulf spawning grounds. Brown shrimp use bays mainly during spring.
White shrimp use estuaries from late spring through fall. The wellbeing of young shrimp while in estuaries is critical to the success of
sport, live-bait and commercial shrimp fisheries.
The state shrimp program, begun 16 years ago, was designed to
help shrimpers obtain large catches. When brown shrimp leave bays they
are still less than the minimum legal size of 108 mm (65 headless shrimp
to a pound). Therefore, Texas law provides for a 45—day closed season
in the shallow Gulf (from the coast out to 10 nautical miles). The
Parks and Wildlife Commission has the responsibility of recommending
a starting date for the closed season that coincides with the start
of emigration. Depending on the results of systematic shrimp sampling
in bays, the beginning of the closed season may be set as early as
15 May or as late as 15 June.
Although the fall bay season and minimum legal size are set by
law, white shrimp were sampled during summer and fall to determine if
there were areas consistently inhabited by undersize whites (over 65
headless to a pound) within commercially fished bays.
The results of previous efforts in this project were reported by
Leary and Compton (i960), Compton (1962), Pullen 0-963), Moffett U-964,
1965a, b, 1966, 1967, 1968, 1969, 1970, 1971, 1972) and Moffett and
McEachron (1973). This report is a review of the 1974 shrimp sampling
program, the effects of increased fishing on catch and the collapse of
the Sabine Lake shrimp fishery.
MATERIALS AND METHODS
Brown Shrimp Samples (Spring, 1974)
Definitions of shrimp sampling areas were described by Leary and
Compton (1960): 1) nursery areas or tertiary bay stations (areas of
estuaries 1-2 ft deep used by shrimp during their early days in bays,
e.g., salt marshes, shallow back bays and small bayous); 2) secondary
bay stations (bays 4-5 ft deep, through which shrimp 40-70 mm long pass,
e.g., Clear Lake, Jones Lake and Moses Lake); and 3) primary bay stations
(stations in large bays usually deeper than 6 ft, e.g., Galveston Bay,
Matagorda Bay and Aransas Bay).
Between 1 April and 1 June, shrimp were sampled weekly at desig­
nated stations in Galveston, Matagorda and Aransas Bays and twice a
month in the Lower Laguna Madre (Figure 1 ) . Shrimp in Sabine Lake
were sampled twice a week in May.
Two kinds of sampling gear were used:
1)
bar seines, 1.8 m (6 ft) wide, 1.3 cm (0.5 in) mesh, pulled
152.4 m (500 ft) by hand in nursery areas; and
2)
trawls, 3.05 m (10 ft) wide, 3.2 cm (1.25 in) mesh, 1.3 cm
(0.5 in) mesh liner in cod end, pulled 15 min per station
(2 mi/hr) in secondary and primary bays.
Shrimp were counted and measured to the nearest millimeter (tip of
rostrum to end of telson).
Shrimp Samples (Summer and Fall, 1974)
Shrimp were sampled twice a month at designated stations (Figure
2) on the commercial shrimping grounds of Galveston, Matagorda and
Aransas Bays with 2 kinds of trawls:
1)
6.1 m (20 ft) wide, 3.8 cm (1.5 in) mesh, pulled 15 min
per station (2 mi/hr) on commercial shrimping grounds; and
2)
3.05 (10 ft) wide, 3.2 cm (1.25 in) mesh, 1.3 cm (0.5 in)
mesh liner in cod end, pulled 5 min per station in secondary
bays.
Shrimp measured to the midpoint of 5-mm intervals were converted
to count sizes (number of headless shrimp to a pound). White shrimp
over 113 mm and brown shrimp over 108 mm long are 65 count or less.
Hydrological Data
Water samples were taken at each station, Bay temperatures (°C)
were determined with mercury thermometers, Salinity (o/oo) was deter­
mined with Goldberg refractometers.
Shrimp Harvest Data
Commercial landing statistics were taken from Shrimp Landings and
Gulf Coast Shrimp Data (U. S. Department of Commerce in cooperation
with the fishery agencies of North Carolina, South Carolina, Georgia,
Florida, Alabama, Mississippi, Louisiana and Texas). Landings included
all shrimp landed in Texas ports regardless of where they were caught.
Weights were on a heads-off basis. Values were ex^-vessel prices.
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RESULTS
Sabine Lake
Brown shrimp availability: In early May departmental personnel
reported an abundance of brown shrimp in Shell Lake, a small brackish
lake connected to Sabine Lake by the Gulf Intracoastal Waterway (GIWW).
However, few shrimp (1 per sample on 1 May, 15 per sample on 15 May)
were found in Sabine Lake. The largest sample (45 shrimp) was taken
on 17 May at the southernmost station near the causeway that spans
Sabine Pass.
Size range of brown shrimp: On 2 May, the size range of brown
shrimp was 38-58 mm. By 17 May brown shrimp were 29-64 mm long.
Commercial landings and value:
reported in 1974.
No commercial shrimp catch was
Water salinity and temperature; Average water salinity values
ranged from 2.5 o/oo on 2 May to 8.9 o/oo on 17 May. Water temperature
ranged from 24.0 °C on 2 May to 26.5 °C on 17 May.
Galveston Bay
Brown shrimp availability: The average number of brown shrimp
in samples from nursery areas, a secondary bay (Clear Lake) and the
primary bay (Galveston Bay) in the springs of 1971, 1972, 1973 and 1974
are shown in Table 1. In 1974 the average number of shrimp in nursery
area samples ranged from a low of 68 on 1 April to a high of 268 on 23
May. Between 1971 and 1973 the greatest average per sample was 793
(1 May 1972). On 1 May 1971 and 1972 the average catch value peaked
at 509 and 793 shrimp respectively. Catch values declined to 258 shrimp
per sample on 23 May 1971 and to 51 per sample on 23 May 1972. The
maximum catch (88 shrimp) in 1973 was taken on 15 May.
In 1974 brown shrimp were available in the secondary bay between
23 April C28 shrimp) and 23 May (63 shrimp). The total number of
shrimp caught during the sampling period was 518 in 1971, 445 in 1972,
26 in 1973 and 188 in 1974. Availability peaks occurred on 5 May 1971
(182 shrimp), 1 May 1972 (166 shrimp), 23 May 1973 (19 shrimp) and
15 May 1974 (78 shrimp).
The availability of brown shrimp at primary bay stations in 1974
was greatest on 15 May (75 shrimp), declining to 71 shrimp on 23 May.
Other periods of maximum availability were 23 May 1971 (105 per sample),
15 May 1972 (177 per sample) and 23 May 1973 (21 per sample).
Shrimp data from Sabine Lake on file at Seabrook Marine Laboratory.
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Size range of brown shrimp: Figure 3 shows the size distribution
of brown shrimp in the Galveston Bay System during 1974. The curves
were smoothed by averaging sets of three data points to eliminate minor
fluctuations in the data. The size range of brown shrimp at sampled
nursery areas was 8-88 mm. When sampling began on 1 April, the size
range was 8-33 mm Cmode: 23 mm). Brown shrimp in the sampled secondary
bays were 23-108 mm long on 15 May. Those in samples from the primary
bay were 33-103 mm long (mode: 68 mm) on 15 May and 43-118 mm (mode:
73 mm) on 23 May.
Count sizes of white shrimp: Of 3,642 white shrimp sampled on the
commercial shrimping grounds of Galveston Bay between July and November,
31.9% were legal size (65 tails to a pound). Of these 10.4% were
40 count or less; 0.6% were 25 count or less (Table 2). In 1973, 20.8%
of the sampled white shrimp population were legal size; in 1972, 57%
were legal size (Moffett 1972).
During the first two weeks of August, 75.9% of 384 white shrimp
sampled on the Galveston Bay commercial shrimping grounds were 65 count
or less. The greatest number of legal size shrimp (89.2% of 213 shrimp)
was caught in upper Galveston Bay. In upper Trinity Bay 58.6% of the
shrimp sampled were legal size; 80.0% of the shrimp in lower Trinity
Bay were legal size (Table 2). In November only small percentages of
white shrimp were legal size in upper Trinity (13,6%), upper Galveston
(5.0%), lower Galveston (2.2%) and lower Trinity (1.8%) Bays.
Small numbers of legal size whites were available in Clear Lake
(14.6% of 404 shrimp), Dickinson Bay (1.6% of 422 shrimp), Moses Lake
(2.9% of 371 shrimp), Jones Lake (5.3% of 19 shrimp) and Chocolate
Bay (3.2% of 721 shrimp) (Table 3). These samples, collected between
June and November, also contained 314 brown shrimp of which 1.6% were
65 count or less.
Commercial landings and values: Table 4 presents the annual
shrimp catches (heads-off) and dollar values to fishermen for years
1971-1974. The annual brown shrimp catch of 577,601 kg (1,273,372 lb)
in 1971 dropped to 269,171 kg (593,411 lb) in 1973, then increased
to 404,819 kg (883,640 lb) in 1974. The white shrimp catch ranged
from a high of 1,205,074 kg (2,647,870 lb) in 1973 to a low of 704,658
kg (1,553,479 lb). The dollar value to fishermen dropped from $3,342,482
in 1973 to $1,811,311 in 1974.
Water salinity and temperature: The average water temperature
and salinity values based on data collected while shrimp sampling are
presented in Table 5. Salinity averaged 16,5 o/oo or less during
April-May, increasing to 17,3 o/oo in August, then decreasing to
3.4 o/oo in November.
Matagorda Bay
Brown shrimp availability: The average number of brown shrimp
in nursery area samples ranged from 13 on 1 April to 91 on 8 May,
decreasing to 26 by 23 May (Table 6 ) . Between 1971 and 1974 the
greatest average number of shrimp per sample was 442, on 1 May 1971,
The average number of shrimp in secondary bay samples peaked
at 66 on 8 May, but data were unavailable for 1 April, 8 April or
15 May. Abundance maxima occurred on 23 May 1971 (77 shrimp), 23
April 1972 (161 shrimp) and 23 May 1973 (160 shrimp).
The highest average number of shrimp in primary bay samples was
48 on 8 May, but data were unavailable for 1 April,8 April or 15 May.
Abundance maxima occurred on 23 May 1971 (59 shrimp), 1972 (187 shrimp)
and 1973 (109 shrimp).
Size range of brown shrimp: Figure 4 shows the size distribution
of brown shrimp in the Matagorda Bay System during 1974. The curves
were smoothed by averaging sets of three data points to eliminate minor
fluctuations in the data. The size range of brown shrimp in nursery
area samples was 23-83 mm. On 1 April the size range was 13-48 mm
(mode: 23 mm).
The brown shrimp size range in secondary bay samples was 28-88 mm
on 23 April, 33-104 mm on 1 May, 28-93 mm on 8 May and 28-98 mm on
23 May. At the primary bay stations shrimp were 43-98 mm long on
8 May.
Count sizes of white shrimp: In 1973, 12,3% of 1,300 sampled
white shrimp were legal size (65 count or less) (Moffett and McEachron
1973). Of 3,380 white shrimp sampled on the commercial shrimping
grounds between June and October 1974, 24.6% were legal size, 2.4%
were 40 count or less and 0.6% were 25 count or less (Table 7 ) . The
largest percentage of legal size shrimp (30.5% of 1,155 shrimp) was
caught in the Mad Island area; the smallest was caught in the Hotel
Point area (19.1% of 973 shrimp). The abundance of legal size white
shrimp ranged from a low of 9.6% in late October to a high of 30.9%
in early August.
Small percentages of legal size white shrimp were found in
Carancahua Bay (7.8% of 153 shrimp), Colorado River (0.8% of 121
shrimp), Tres Palacios River (0.0% of 352 shrimp) and Lavaca Bay
(1.3% of 675 shrimp) (Table 8). In addition, these samples, collected
between June and October, contained 99 brown shrimp all of which were
under-size.
Commercial landings and value: The commercial brown shrimp catch
ranged from 61,228 kg (134,983 lb) in 1971 to 246,757 kg (543,998 lb)
in 1973 (Table 9 ) . White shrimp landings ranged from 315,161 kg
(694,801 lb) in 1971 to 847,102 kg (1,867,509 lb) in 1973. The value
to the fishermen of $821,197 in 1971 increased to $2,641,533 in 1973,
then decreased to $1,239,064 in 1974.
Water salinity and temperature: During April-May the salinity
increased from 8.5 o/oo (1 April) to 16.1 o/oo (15 April),then decreased
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to a low of 0.4 o/oo (15 May). Highest average salinities were re­
corded in August (21.2 o/oo) and September (20.2 o/oo). Water tem­
perature ranged from a low of 17.0 °C on 8 April to a high of 28.6 °C
in July.
Aransas Bay
Brown shrimp availability: The average number
in nursery area samples increased from 50 on 1 April
on 8 May, decreasing to 42 on 5 May and 49 on 23 May
Between 1971 and 1974 the greatest average number of
was 362, on 1 May 1971.
of brown shrimp
to a high of 190
(Table 11).
shrimp per sample
The average number of shrimp in secondary bay samples peaked
at 102 (15 May). During the previous three years the greatest average
catch was 152 shrimp (23 May 1973).
At primary bay stations the average catch peaked at 684 shrimp
(23 May). In 1973 the average catch peaked at 1,075 shrimp (23 May).
Size range of brown shrimp: Figure 5 shows the size distribution
of brown shrimp in the Aransas Bay system during 1974. The curves
were smoothed by averaging sets of three data points to eliminate minor
fluctuations in the data. The size range of brown shrimp in nursery
area samples was 13-83 mm. On 1 April, when sampling began, shrimp
were 13-43 mm in nursery areas. The size range of shrimp in secondary
bay samples was 43-118 mm on 15 May (time of maximum availability).
In primary bay samples the size range was 38-139 mm (mode: 63 'mm) on
1 May, 43-113 mm (mode: 63 mm) on 8 May, 43-103 mm (mode: 73 mm)
on 15 May and 43-123 mm (mode: 73 mm) on 23 May.
Count sizes of white shrimp: Between July and October 1974, 736
white shrimp were collected on bay commercial shrimping grounds. Of
these, 39.5% were legal size (65 count or less), 33.9% were 40 count
or less and 10.9% were 25 count or less (Table 12). During August
89.5% of 105 shrimp were legal size and 70.5% were 40 count or less.
The percentage of legal size shrimp remained relatively high in September
(48.7% of 116 shrimp) and October (59.8% of 437 shrimp).
Between mid-July and October the percentage of legal size white
shrimp was lowest at the Fulton Beach station—21.4% on 16 July, 88,1%
on 13 August, 15.4% on 17 September and 50.0% on 1 October.
Commercial landings and value: The annual commercial brown
shrimp catch ranged from a low of 22,226 kg (49,000 lb) in 1971 to
247,167 kg (544,900 lb) in 1973 (Table 13). While shrimp catches ranged
from 101,262 kg (223,240 lb) in 1971 to 315,926 kg (696,486 lb) in 1972.
The 1974 brown shrimp catch was 59,422 kg (131,000 lb); the white
shrimp catch was 208,034 kg (458,628 lb). The dollar value to fishermen
was $247,279 in 1971, $915,837 in 1972 and $1,079,057 in 1973, decreasing
to $594,426 in 1974.
Water salinity and temperature; The average water temperature
and salinity values based on data collected while shrimp sampling
are presented in Table 14. The temperature ranged from a low of 19.2 °C
(15 April) to a high of 29.8 °C (August). The salinity was fairly
stable (9.9-11.7 o/oo) during April-May, reaching a maximum of 21.2 o/oo
in August, decreasing to 9.1 o/oo in September and 9.3 o/oo in October.
Lower Laguna Madre
Brown shrimp availability: In 1974 the average number of brown
shrimp in nursery area samples increased from 64 on 1 April to 96 on
15 April, decreased to 62 on 1 May, then increased to 133 on 15 May
(Table 15). Abundance maxima occurred on 1 April 1971 (80 shrimp),
1 April 1972 (33 shrimp) and 15 May 1973 (242 shrimp). Abundance
maxima at secondary bay stations occurred on 1 April 1971 (162 shrimp),
1 May 1972 (264 shrimp), 1 May 1973 (650 shrimp) and 15 May 1974
(596 shrimp).
Size range of.brown shrimp: Figure 6 shows the size distribution
of brown shrimp in the Lower Laguna Madre Bay system during 1974. The
curves were smoothed by averaging sets of three data points to eliminate
minor fluctuation in the data. The size range of brown shrimp in nursery
area samples was 13-78 mm. On 1 April when sampling began shrimp
were 23-78 mm (mode: 28 mm). Brown shrimp at secondary bay stations
(Laguna Madre is considered a secondary bay) were 23-88 mm (mode: 43 mm)
on 1 April, 23-83 mm on 15 April, 23-103 mm (mode: 58 mm) on 1 May
and 23-103 mm (mode: 48 mm) on 15 May.
Water salinity and temperature: The average water salinity values
taken on sampling dates ranged from 21,7 o/oo (1 April) to 38.7 o/oo
(1 May). The temperature range was 20.4 °C (15 April) - 24.8 °C
(15 May).
Brown Shrimp Growth
Brown shrimp growth rate estimates were derived from an analysis
of the length-frequency distributions shown in Figures 3-6. Average
growth was determined by the method of Williams (1955) which relates
shrimp growth to the extreme length differential between sampling
dates.
The estimated growth rate of shrimp was 1.5 mm per day in Galveston
(33 mm on 1 April - 103 mm on 15 May; increment: 70 m m ) , Matagorda
(58 mm on 8 April - 103 mm on 8 May; increment: 45 mm) and Aransas
(43 mm on 1 April - 123 mm on 23 May; increment: 80 mm) Bays. Growth
rate estimates were not attempted for Sabine Lake shrimp due to a lack
of data nor for Laguna Madre shrimp due to an apparent early emigration
of juveniles that tended to depress the length-frequency distributions.
Emigration of Brown Shrimp
From an examination of the length-frequency distributions in
Figures 3-6, it was suggested that the major shrimp emigration would
begin in late May or early June. The approximate starting time of
emigration is indicated by concentrations of brown shrimp longer
than 70 mm in bay areas near bay-to-Gulf passes. The modal length
of brown shrimp in Galveston Bay primary stations was 68 mm on 15 May
and 73 mm on 23 May. The modal length of shrimp was 83 mm in Matagorda
Bay and 13 mm in Aransas Bay on 23 May. Brown shrimp data from the
Lower Laguna Madre indicated an offshore movement of brown shrimp
between 1 May (modal length: 58 mm) and 15 May (modal length: 48 mm).
Apparently the majority left the Laguna Madre after 15 May since
juveniles were still abundant then (596 per sample). Using these data
it was suggested that a portion of the brown shrimp would leave the
bays early but that the major emigration would begin in late May.
Apparently the egression period was long-lasting since numerous small
juveniles were present on nursery grounds of Galveston Bay (268 per
sample) on 23 May and at secondary bay stations of the Laguna Madre
(596 per sample) on 15 May.
Commercial Shrimp Landings
In 1974 Texas fishermen landed 21.0 million kg (49.4 million lb)
of shrimp worth $67.7 million wholesale (Christmas and Etzold 1977).
The catch included 16.1 million kg (35.5 million lb) of brown shrimp,
5.2 million kg (11.5 million lb) of white shrimp, 635.0 thousand kg
(1.4 million lb) of pink shrimp, 387.6 thousand kg (854.4 thousand lb)
of seabob and 35.3 thousand kg (77.9 thousand lb) of royal red shrimp.
Brown shrimp landings increased 952.6 thousand kg (2.1 million lb)
over 1973 but were 5.8 million kg (12.8 million lb) less than the 1972
catch (Table 17). White shrimp landings were 1.5 million kg (3.4
million lb) less than the record 1973 catch of 6.8 million kg (14,9
million lb).
2
Relationship Between Catch Per-Unit-Effort and Catch in Sub-area 18
Many trawlers have been added to the shrimp fleet since 1965,
leading to a reduced brown shrimp catch per-unit-effort but not a
significant increase in total catch, A comparison of the commercial
brown shrimp catch per day fished in sub-area 18 (in the Gulf off
Galveston) and annual brown shrimp catches in the same sub-area in­
dicates a gradual decrease in catch per day fished since 1968 (Figure
7). Total annual catches, although irregular, do not show this trend.
In contrast, white shrimp landings and catch per day fished in subarea 18 indicate an increasing trend in catch per-unit-effort and
total catch.
Source:
Gulf Coast Shrimp Data, Annual Summaries: 1962-1973.
Relationship Between Catch Per-Unit-Effort, Effort and Catch (Sabine
Lake and Sub-area 17)
Shrimp catches from Sabine Lake have declined sharply in recent
years (Table 18). Since 1965 the annual brown shrimp catches have
not exceeded 10 lb. The annual white shrimp catches have declined
from well over 300 thousand lb in 1965 to 6,000 lb in 1972. In con­
trast, shrimp catches from nearby Calcasieu Lake in Louisiana have not
declined. The decline in the Sabine Lake fishery was accompanied by a
reduction in total effort units but not by a reduction in catch perunit-effort3, indicating that Sabine Lake shrimpers made relatively
good catches but total catches were low due to poor shrimp stocks.
Shrimp catches in the Gulf off Sabine and Calcasieu Lakes (subarea 17) did not show a decline (Table 19), probably a result of
increased fishing. The annual number of effort units for brown shrimp
ranged from 2,349.9 to 6,676.7 between 1962 and 1968 and from 6,837.8
to 11,103.5 between 1969 and 1973. White shrimp effort units ranged
from 3,980.2 to 9,720.0 between 1962 and 1968 and from 12,600.9 to
25,058.3 between 1-969 and 1973. The 1969-73 period was marked by a
reduction in white shrimp catch per-unit-effort compared with the
1962-68 period.
DISCUSSION AND MANAGEMENT
Brown shrimp sizes in early April 1974 were indicative of a weak
year-class and a poor uncoming season. In early April the young on the
nursery grounds were relatively large and a possible premature migration
was expected. However, an early starting date for the closed 45-day
season (established by Texas law) in the shallow Gulf was not recommended
because large numbers of postlarvae were detected in April and May.
By 17 May, however, shrimpers found an abundance of illegal size brown
shrimp in the Gulf off Aransas Bay. Retaining the usual 1 June starting
date for the closed Gulf season was justified because the egression
period was long-lasting. In fact, the broods of postlarvae detected
on the nursery grounds of Galveston Bay and the Lower Laguna Madre
were unusually large.
Although these late pre-recruitment groups of small shrimp in bays
indicated that the stocks may have been adequate, the brown shrimp
season was poor and Gulf shrimpers experienced the second disastrous
season in a row. In 1973 the brown shrimp catch (the lowest since
1964) was apparently reduced by Inadequate stock density. Moffett and
McEachron (1973) reported that interrupted brown shrimp growth and poor
survival were caused primarily by low water temperature in April and
The number ot effort units was obtained by dividing total catch by
catch per-unit-effort. Catch per-unit-effort was obtained by dividing
catch (based on interview data) by number of days fished. These
data are published in the Gulf Coast Shrimp Data, Annual Summaries:
1962-1973.
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low salinity in upper coastal bays during spring. The 1974 catch
reduction was probably a result of inflated operational costs and
low shrimp prices to shrimpers, causing many of them to remain in
port and forcing several dockside facilities to close (Farley 1974).
The purpose of sampling white shrimp in Galveston, Matagorda and
Aransas Bays was to determine if certain areas open to commercial
fishing during the fall shrimp season harbor an abundance of small
shrimp. Samples from three seasons did not indicate that large sections
of "major bays" contain a high density of illegal size white shrimp for
an extensive time period before the fall cooling. However, certain
primary bay areas near secondary bays may support a high density of
juveniles for a short time because the young must move through these
areas as they enter primary bays. Sampling has shown that heavy rains
and "northers" will force the young from small back bays into larger
primary bays (Moffett and McEachron, 1973).
These shrimp samples were valuable because they allow a deter­
mination of the size range and modal size of shrimp available to
commercial trawls shortly before and during the fall open bay season.
At present this season is fixed by law; if future laws permit a flexible
starting date, the Parks and Wildlife Commission will be able to adjust
the season to begin when a large percentage of the shrimp are legal
size.
The data also showed that in the fall white shrimp leave secondary
bays to enter larger bays, becoming vulnerable to the fishery. If
the winter is mild, these small white shrimp may contribute heavily
to catches the next spring; therefore, restricted shrimping in late
fall may have some management merit.
Using commercial catch data from the Gulf near Galveston, evidence
was found of a reduced brown shrimp catch per-unit-effort, apparently
caused by increased fishing pressure which accompanied the growth of
the shrimp fleet. The total catch, however, showed no significant
increase. It is possible that the reduced catch per-unit-effort
reflected low stock density, but a more likely cause was increased
fishing pressure. Since shrimpers now have to fish longer to show a
profit, it may be necessary to restrict the number of vessels.
White and Perrett (1973) related the shrimp catch decline in
Sabine Lake to the operational procedures of the Toledo Bend Dam
(completed in 1967). They suggested that the large winter river dis­
charges released in mid-May exposed postlarval white shrimp and juvenile
brown shrimp in the lake to harmful low salinity conditions from midMay through June.
Another apparently detrimental factor to shrimp stocks in Sabine
Lake was the closing of the pass between Keith Lake and the Port Arthur
ship channel in 1965, after which Keith Lake and other lakes connected
to it could not be fully utilized as shrimp nursery grounds. Parks
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and Wxldlife personnel have proposed the construction of a permanent
opening to the channel, allowing postlarval shrimp to enter Keith
Lake on incoming tides, to use the estuary as a nursery ground and
to leave as juveniles at a later time. Ideally, this will help increase
shrimp populations in the Gulf off Sabine Pass and perhaps in Sabine
Lake.
Reliable values of total mortality, fishing mortality and growth
rates are needed to determine size at first harvest for white and
brown shrimp. Biologists of the National Marine Fisheries Service
and the Parks and Wildlife Department had planned a white shrimp tagging
experiment to obtain such information; however, a lack of proper size
shrimp for tagging forced a postponement of the effort.
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LITERATURE CITED
Christmas, J. W. and D. J. Etzold (eds.). 1977. The shrimp fishery
of the Gulf of Mexico United States: A regional management plan.
Gulf Coast Res. Lab. Tech. Rep. Ser. 2: 1-128.
Compton, H. 1962. A study of the bay populations of juvenile shrimp,
Penaeus aztecus, and Penaeus duorarum. Mar. Fish, Div. Prog.
Reps. 1960-61; Texas Game and Fish Comm., (Mimeo): 1-28.
Farley, 0. H. 1974. Trends and conditions in the fisheries of Texas.
NMFS, Galveston.
Leary, T. and H. Compton. 1960. A study of the bay populations of
juvenile shrimp Penaeus aztecus and Penaeus setiferus. Mar.
Fish. Div., Proj. Reps. 1959-60, Texas Game and Fish Comm.,
(Mimeo): 1-32.
Moffett, A. W. 1964. A study of the Texas bay populations of juvenile
shrimp, Penaeus aztecus, Penaeus setiferus, and Penaeus duorarum.
Coastal Fish. Proj. Reps. 1963, Texas Parks and Wildl. Dept.,
(Mimeo): 1-49.
. 1965a. A study of the Texas bay populations of juvenile
shrimp, Penaeus aztecus, Penaeus setiferus, and Penaeus duorarum.
Coastal Fish. Div., Proj, Reps. 1964, Texas Parks and Wildl.
Dept., (Mimeo): 1-46.
. 1965b. A study of Texas shrimp populations. Coastal
Fish Div., Proj. Reps. 1965, Texas Parks and Wildl. Dept. (Mimeo):
1-28.
. 1966. A study of commercial shrimps in coastal bays
of Texas. Coastal Fish. Div., Proj. Reps., Texas Parks and Wildl.
Dept., (Mimeo): 1-26.
. 1967. A study of commercial shrimp populations in
coastal bays of Texas, 1967. Coastal Fish. Div., Proj. Reps.,
Texas Parks and Wildl. Dept., (Mimeo): 19-48.
. 1968. A study of commercial shrimp populations in
coastal bays of Texas, 1968. Coastal Fish. Div., Proj. Reps.,
Texas Parks and Wildl. Dept., (Mimeo): 67-93.
. 1969. A study of commercial shrimp populations in
coastal bays of Texas, 1969. Coastal Fish. Div., Proj. Reps.,
Texas Parks and Wildl. Dept., (Mimeo): 169-183.
. 1970. A study of commercial shrimp populations in
coastal bays of Texas, 1970. Coastal Fish. Div., Proj. Reps.,
Texas Parks and Wildl. Dept., (Mimeo): 185-206.
-13-
, 1971. A study of brown shrimp in Texas coastal bays
(spring 1971). Coastal Fish. Div., Proj. Reps., Texas Parks
and Wildl. Dept., (Mimeo): 191-208.
. 1972. A study of brown shrimp (Penaeus aztecus) and
white shrimp (P_. setiferus) in coastal bays of Texas, 1972.
Coastal Fish. Div., Proj. Reps. 1972, Texas Parks and Wildl.
Dept., (Mimeo).
and L. W. McEachron, 1973. A study of brown shrimp
(Penaeus aztecus) and white shrimp (P_. setif erus) in coastal bays
of Texas, 1973. Coastal Fish. Div., Proj. Reps. 1973, Texas
Parks and Wildl. Dept., (Mimeo),
Pullen, E. J. 1963. A study of the bay and Gulf populations of
shrimp Penaeus aztecus, Penaeus setiferus, and Penaeus duorarum.
Coastal Fish. Div., Proj. Reps. 1961-62, 1-53, Texas Parks and
Wildl. Dept., (Mimeo).
U. S. Department of Commerce 1962-1973 Gulf Coast Shrimp Data.
Cur. Fish. Stat. Annual Summaries 1962-1973.
NMFS
White, C. J. and W. S. Perrett. 1973. Short term effects of the
Toledo Bend Project on Sabine Lake, Louisiana. Procs. 27th Ann.
Conference, Southeastern Association of Game and Fish Commissioners.
Hot Springs, Ark,
Williams, A. B. 1955. A contribution to the life histories of commercial
shrimps (Penaeidae) in North Carolina. Bull. Mar. Sci. Gulf Caribb.
5: 116-156.
-14-
Table 1
Average number of brown shrimp per sample
(1971-1974)
GALVESTON BAY
Year
1971
1972
1973
1974
No.
55
0
14
64
14
60
88
41
No.
68
121
90
94
200
124
188
268
Tertiary Bays
Date*
4-1
4-8
4-15
4-23
5-1
5-8
5-15
5-23
No.
14
16
71
169
509
295
379
258
No.
92
161
687
325
793
486
98
51
Bays
4-1
4-8
4-15
4-23
5-1
5-8
5-15
5-23
2
3
2
19
120
43
182
147
1
4
3
50
166
158
22
41
0
0
0
0
2
2
3
19
0
0
0
28
10
9
78
63
0
0
0
1
0
20
7
21
0
0
0
0
1
2
75
71
Primary Bays
4-1
4-8
4-15
4-23
5-1
5-8
5-15
5-23
0
0
1
0
1
19
14
105
7
0
2
6
7
20
177
6
Samples were taken within three days of
these dates.
-15-
Table 2
Change in percentage of white shrimp with count size at "commercial stations" in Galveston and Trinity Bays (1973-1974)
113 mm or longer (%)
(65 count or less)
Number
Approximate
Date
1973
1974
1973
1974
133 mm or longer C
(40 count or less)
153 mm or longer (%)
(25 count or less)
1973
1974
1973
1974
8.8
3.3
10.4
1.4
0.5
1.6
0.0
0.8
2.5
-
51.6
40.0
14.0
0.0
1.5
2.9
0.0
12.3
1.1
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0,1
0.9
0.0
0.0
0.0
0.0
0.0
0.0
0.2
1.1
11.7
0.0
0.0
28.5
4.2
0.0
0.8
3.5
0.0
0.0
0.0
50.0
37.2
0.0
1.8
0.0
6.4
0.0
0.7
0.0
0.0
0.0
0.0
0.0
0.0
0.0
100.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.5
UPPER GALVESTON BAY
ON
I
July
Aug. 1
Aug. 16
Sept. 1
Sept. 16
Oct. 1
Oct. 16
Nov.
Total
112
233
48
274
442
239
462
337
2147
213
16
270
137
198
542
178
1554
11.0
39.2
45.8
11.6
21.5
21.7
7.6
4.3
19.5
-
89.2
60.0
45.5
19.8
14.5
17.2
5.0
38.4
LOWER GALVESTON BAY
July
Aug. 1
Aug. 16
Sept. 1
Sept. 16
Oct. 1
Oct. 16
Nov.
Total
*
<*
143
449
36
13
85
211
69
163
1169
2
0
3
18
12
8
171
136
350
13.5
39.4
36.1
38.5
65.7
34.3
20.0
4.3
32.4
0.0
0.0
33.3
75.0
62.5
20.0
14.9
2.2
18.8
•
♦
«
4
V
t
J*
m
*
Table 2 cont'd.
Number
Approximate
Date
1973
1974
113 mm or longer ,
(65 count or less)
133 mm or longer ,
(40 count or less)
153 mm or longer
(25 count or less)
1973
1973
1974
1973
1974
0.0
0.0
0,
0,
0,
0,
0.0
15.7
40.0
11.8
20.0
0.0
0.0
1.2
5.9
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.
1,
0,
0.
0,
0,
0,
1,
0,
0,
32,
50,
3,
16,
0,
0,
1,
4
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0
10.4
0.0
0.6
1974
UPPER TRINITY BAY
1
H
1
Aug. 1
Aug. 16
Sept. 1
Sept. 16
Oct. 1
Oct. 16
Nov.
Total
17
168
87
47
150
208
606
150
1433
6
146
5
26
8
80
257
579
1101
0.0
25.0
28.7
9.1
20.0
9.8
1.3
0.0
14.7
0,
58,
100,
23,
60,
18,
17,
13,
30,
LOWER TRINITY BAY
July
Aug. 1
Aug. 16
Sept. 1
Sept. 16
Oct. 1
Oct. 16
Nov.
Total
3
77
52
22
123
95
294
149
815
4
25
4
183
7
153
48
213
637
0.0
22.5
34.6
28.2
23.0
8.8
1.8
2.0
16.9
50.0
80.0
75.0
18.0
66.6
10.8
59.4
1.8
23.5
0.0
2.5
15.3
5.1
1.3
0.0
0.0
0.0
3.2
Data
Combined
5,564
3,642
20.8
31.9
2.4
Note:
Legal size white shrinp, 65 tails to a pound, are, on the average, 113ramlong; 40 tails to a pound are
133 ram long; 25 tails to a pound are 153 mm long. The average legal size brown shrimp is 108 mm long.
Table 3
Changes in percentage of white and brown shrimp with count size by sampling period - secondary bays of the
Galveston Bay system (1974)
Date
WHITE SHRIMP
% 65 count
Number
or less
BROWN SHRIMP
% 65 count
Number
or less
Date
WHITE SHRIMP
% 65 count
Number
or less
Clear Lake
2 July
23 July
6 Aug.
16 Aug.
18 Sept.
22 Sept.
7 Oct.
17 Oct.
21 Nov.
Total
0
0
55
1
79
29
93
92
55
404
0.0
0.0
34.5
0.0
16.4
75.8
3.2
2.2
0.0
14.6
Chocolate Bay
19
10
1
1
0
0
1
0
0
32
0.0
30.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
9.4
15 July
31 July
14.Aug.
22 Aug.
17 Sept.
8 Oct.
19 Oct.
Total
13
56
47
25
224
342
14
721
0
3
0
0
8
354
54
3
422
0.0
0.0
0.0
0.0
0.0
1.7
1.8
0.0
1.6
7.6
12.5
31.9
0.0
0.0
0.0
0.0
3.2
99
31
1
29
1
0
1
162
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
17
0
5
0
0
0
22
0.0
0.0
0.0
0.0
0.0
0.0
0.0
Jones Lake
Dickinson Bay
10 July
25 July
6 Aug.
16 Aug.
11 Sept.
25 Sept.
17 Oct.
4 Nov.
Total
BROWN SHRIMP
% 65 count
or less
Number
18
19
0
1
1
14
0
0
53
0.0
5.2
0.0
0.0
0.0
0.0
0.0
0.0
1.9
15 July
31 July
14 Aug.
22 Aug.
17 Sept.
19 Nov.
Total
5
1
3
0
2
8
19
0.0
0.0
33.3
0.0
0.0
0.0
5.3
V
V
»
.
*
»
<*
Table 3 cont'd.
WHITE SHRIMP
% 65 count
Number
or less
Date
BROWN SHRIMP
% 65 count
Number
or less
Moses Lake
10 July
25 July
6 Aug.
16 Aug.
11 Sept.
17 Oct.
4 Nov.
Total
Note:
3
16
112
26
0
164
50
371
33.3
0.0
1.8
7.7
0.0
3.0
2.0
2.9
Date
WHITE SHRIMP
% 65 count
Number
or less
BROWN SHRIMP
% 65 count
Number
or less
West Galveston Bay (Upper & Lower)
23
0
2
4
0
1
9
39
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
15 July
0
31 July
0
14 Aug.
0
22 Aug.
0
17 Sept.
0
8 Oct.
0
17 Nov.
0
Total
0
Data Pooled
(all areas)1937
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
2
0
1
1
1
1
0
6
5.2
314
0.0
0.0
0.0
100.0
0.0
0.0
0.0
16.6
1.6
Legal size white shrimp, 65 tails to a pound, are, on the average, 113 mm long; 40 tails to a pound
are ]33 mm long; 25 tails to a pound are 153 mm long. The average legal size brown shrimp is
108 mm long,
Table 4
Commercial Catches and Dollar Value to Fishermen
(Galveston Bay 1971-1974)
Year
Brown Shrimp
lb
White Shrimp
lb
Value
$
1971
1,273,372
1,923,925
2,054,770
1972
902,461
2,070,394
2,749,743
1973
593,411
2,647,870
3,342,482
1974
883,640
1,553,479
1,811,311
Source:
Gulf Coast Shrimp Data
Table 5
Average Water Salinity and Water Temperature Values
Salinity
o/(
Temperature
°C
Salinity
o/oo
Temperature
Date
1 April
14.4
21.5
June
12.8
28.0
8
14.3
19.2
July
14.0
28.5
15
11.4
20.2
Aug.
17.3
29.7
23
14.1
23.5
Sept.
13.0
28.0
1 May
15.2
24.0
Oct.
13.4
21.9
8
16.5
23.4
Nov.
3.4
20.5
15
9.2
25.2
Dec.
-
23
11.9
25.7
Date
-20-
-
Table 6
Average Number of Brown Shrimp Per Sample
(1971-1974)
MATAGOKDA BAY
Year
1971
1972
1973
1974
No.
126
24
8
2
10
14
78
85
No.
13
46
60
54
34
91
5
8
4
15
_
-
Tertiary Bays
Date
No.
No.
4-1
4-8
64
200
102
59
442
212
212
66
395
405
147
120
68
178
39
52
4-15
4-23
5-1
5-8
5-15
5-23
-*
26
Secondary Bays
5-1
5-8
0
1
3
8
34
17
5-15
5-23
77
4-1
4-8
4-15
4-23
-
6
34
39
161
131
156
74
152
-
16
59
160
10
24
7
66
-
26
Primary Bays
4-1
4-8
4-15
4-23
5-1
5-8
5-15
5-23
0
0
4
4
-
6
-
59
0
10
63
104
77
22
24
187
*
No Data
-21-
1
7
1
0
-
36
60
109
_
-
3
8
10
48
-
13
Table 7
Change in percentage of white shrimp with size at "commercial stations" in
Matagorda Bay (1974)
Station
Number
113 mm or
longer (%)
133 mm or
longer (%)
153 mm or
longer (%)
26-27 June 1974
Hotel Point
Mad Island
Lavaca
Carancahua Bay
Total
21
8
6
5
40
0.0
0.0
50.0
100.0
20.0
0.0
0.0
50.0
100.0
20.0
0.0
0.0
33.3
80.0
15.0
0.6
1.5
0.0
1.1
0.0
0.0
0.0
0.0
6.0
2.0
1.0
0.0
2.6
0.0
0.0
0.0
0.0
0.0
4.4
0.0
0.0
2.7
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
July
Hotel Point
Mad Island
Lavaca Bay
Total
350
923
0
1 ,273
14.0
32.5
0.0
24.4
5-8- August
Hotel Point
Mad Island
Lavaca Bay
Palacios Channel
Total
602
138
910
206
1 ,856
31.0
35.0
18.0
48.0
30.9
30 September
Mad Island
Lavaca Bay
Palacios Channel
Total
46
10
19
75
32.6
20.0
15.8
26.7
29 October
Mad Island
Lavaca Bay
Palacios Channel
Total
40
2
92
136
12.5
50.0
6.5
9.6
Data Combined
0.0
2.5
19.1
973
Hotel Point
1.8
0.0
30.5
Mad Island
1 ,155
3.3
1.7
20.8
930
Lavaca Bay
100.0
100.0
80.0
5
Carancahua Bay
0.0
0.0
20.5
317
Palacios Channel
24.6
2.4
0.6
Total
3 ,380
Note: Legal size white shrimp, 65 tails to a pound, are, on the average,
113 mm long; 40 tails to a pound are 133 mm long; 25 tails to a pound
are 153 mm long. The average legal size brown shrimp is 108 vxm long.
-22-
Table 8
Changes in percentage of white and brown shrimp with count size
in secondary bays of the Matagorda Bay system (1974)
Brown Shrimp
White Shrimp
Date
Number
% 65 Count
or Less
Number
% 65 Count
or Less
Carancahua Bay
28 June
8 July
22 July
7 Aug.
23 Aug.
11 Sept.
30 Sept.
15 Oct.
Total
20
35
11
16
54
0
5
12
153
0.
2,
9,
0,
18,
0,
0,
0.
7,
4
13
0
0
0
0
0
0
17
0.0
0.0
0,
0,
0.
0,
0,
0,
0.
47
1
4
2
0
0
0
0
54
0,
0,
0,
0,
0,
0,
0,
0,
0,
19
2
0
0
0
0
0
21
0,
0,
0,
0,
0,
0,
0,
0,
4
3
0
0
0
0
0
0
7
0,
0,
0,
0,
0,
0,
0,
0,
0,
Colorado River
28 June
5 July
22 July
7 Aug.
23 Aug.
11 Sept.
30 Sept.
15 Oct.
Total
3
0
52
8
0
4
2
52
121
33,
0,
0,
0,
0,
0,
0,
0,
0,
Tres Palacios River
28 June
5 July
22 July
7 Aug.
11 Sept.
30 Sept.
15 Oct.
Total
100
47
17
4
0
34
150
352
0,
0,
0,
0,
0,
0,
0,
0,
Lavaca Bay
38
26 June
8 July
87
22 July
55
5 Aug.
0
23 Aug.
2
11 Sept.
8
30 Sept.
396
15 Oct.
89
Total
675
Data Combined
(all areas) 1 ,301
Note:
0,
0,
3,
0,
100,
62,
0,
0,
1,
1.7
99
0.0
Legal size white shrimp, 65 tails to a pound, are, on the average,
113 mm long; 40 tails to a pound are 133 mm long; 25 tails to a pound
are 153 mm long. The average legal size brown shrimp is 108 mm long.
-23-
Table 9
Commercial Shrimp Catch and Dollar Value to Fishermen (Matagorda Bay
1971-1974)
Year
Brown Shrimp
lb
White Shrimp
lb
1971
134,983
694,801
821,197
1972
147,900
840,449
1,009,495
1973
543,998
1,867,509
2,641,533
1974
291,784
921,267
1,239,064
Source:
Value
$
Gulf Coast Shrimp Data
Table 10
Average Water Salinity and Water Temperature Values
Salinity
o/oo
Temperature
°C
Salinity
o/oo
Temperature
Date
1 April
8.5
28.2
June
12.7
26.7
8
8.4
17.0
July
19.2
28.6
15
16.1
21.4
Aug.
21.2
27.4
23
11.5
25.3
Sept.
20.2
24.0
1 May
7.4
25.2
Oct.
17.5
24.4
8
4.0
25.1
15
0.4
28.7
23
8.3
28.1
Date
-24-
Table 11
Average Number of Brown Shrimp Per Sample (19711974)
ARANSAS BAY
Year
1971
1972
1973
1974
No.
No.
No.
_
101
154
314
247
199
-
15
-
22
22
50
60
30
61
15
190
42
49
Tertiary Bays
Date
No.
4-1
4-8
118„.
*
4-15
4-23
53
-
5-1
5-8
362
5-15
5-23
192
-
94
-
Secondary Bays
4-1
4-8
-
8
2
-
-
-
4-15
4-23
2
132
36
-
-
-
5-1
5-8
3
39
84
-
-
72
152
3
6
35
12
102
73
5-15
5-23
1
49
-
-
Primary Bays
4-1
4-8
-
-
4-15
4-23
4
-
5-1
5-8
5-15
5-23
150
2
2
9
-
-
80
2
-
-
65
181
101
-
-
-
6
25
241
360
123
684
-
No Data
-25-
242
1075
Table 12
i
Change in percentage of white and brown shrimp with size at "commercial" stations
in Aransas Bay (1974)
Area
WHITE SHRIMP
113 mm or
Number longer (%)
133 mm or
longer (%)
BROWN SHRIMP
113 mm or
153 mm or
longer (%) Number longer (%)
1 July 1974
Ranchhouse Area
Marker 37-43
Marker 25-31
LBJ Causeway
Total
1
2
2
34
39
0.0
7.7
8
40
200
104
352
0.0
2.5
0.0
0.0
0.3
0.0
0.0
0.0
0.0
0.0
2
0
2
0
4
0.0
0.0
0.0
0.0
0.0
0
0
0
3
3
0.0
0.0
0.0
0.0
0.0
4
14
32
32
82
0,0
7.1
0.0
0.0
12.1
21.5
168
148
244
196
756
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
100.0
50.0
50.0
100.0
50.0
50.0
100.0
50.0
50.0
5.9
0.0
7.7
12.8
16 July 1974
Ranchouse Area
Marker 37-43
Marker 25-31
Fulton Beach
Total
0
0
5
14
19
0.0
0.0
0.0
0.0
80.0
21.4
36.8
40.0
0.0
10.5
31 July 1974
Ranchhouse Area
Marker 37-43
Marker 25-31
LBJ Causeway
Total
0
0
7
13
20
0.0
0.0
0.0
0.0
0.0
0.0
100.0
76.9
56.6
85.7
30.8
33.3
71.0
0.0
16.7
13 Aug. 1974
Ranchhouse Area
Marker 37-43
Marker 25-31
Fulton Beach
Total
1
4
7
93
105
100.0
100.0
100.0
88.1
89.5
100.0
100.0
85.7
67.7
70.5
0.0
100.0
42.8
16.1
20.9
17 Sept . 1974
Ranchhouse Area
Marker 37-43
Marker 25-31
Fulton Beach
Total
4
8
52
52
116
100.0
100.0
76.9
15.4
48.7
100.0
100.0
69.2
13.5
47.4
25.0
62.5
32.6
3.8
1 Oct. 1974
Ranchhouse Area
Marker 37-43
Marker 25-31
Fulton Beach
Total
32
38
91
276
437
78.1
47.3
69.8
50.0
59.8
56.2
23.7
41.5
37.5
39.0
18.7
10.5
15.1
10.9
13.3
100
101
193
276
670
Data Combined
736
39.5
33.9
10.9
1,867
Note: Legal si*p. white shrimp, 65 tails to a pound, are, on the average, 133 mm
long; 40 tails to a pound are 133 mm long; 25 tails to a pound are 153 mm
long. The average legal size brown shrimp is 108 mm long.
-26-
Table 13
Commercial Catches and Dollar Values to Fishermen (Aransas Bay 19711974)
Year
Brown Shrimp
lb
White Shrimp
lb
1971
49,000
223,240
247,279
1972
85,000
696,486
915,837
1973
544,900
645,200
1,079,057
1974
131,000
458,628
594,426
Source:
Gulf Coast Shrimp Data
-27-
Values
$
Table 14
Average Water Salinity and Water Temperature Values
Salinity
°/oo
Temperature
Date
Salinity
o/oo
Temperature
°C
9.9
22.3
June
-
-
9
15
10.2
19.5
July
19.2
29.1
10.8
19.2
Aug.
21.1
29.8
23
11.7
24.6
Sept.
28.5
11.7
24.3
Oct.
9.1
9.3
10.6
24.5
Nov.
-
-
11.2
26.7
Dec.
-
-
11.7
27.8
Date
1 April
1 May
8
15
23
Table 15
Average Number of Brown Shrimp per Sample (19711974)
LOWER LAGUNA MADRE
Year
1971
1972
Bar Seine
Date
4-1
4-15
5-1
5-15
No.
80
31
31
8
No.
33
_*
25
8
Trawl
4-1
4-15
5-1
5-15
162
152
134
91
238
264
36
•28-
19"74
(nursery areas)
No.
No.
53
114
162
242
64
96
62
133
(secondary bays)
101
16
650
300
-
*
No Data
1973
161
26
278
596
°C
24.0
Table 16
Average Water Salinity and Water Temperature Values
'
Salinity
o/oo
Temperature
°C
1 April
21.7
25.3
15 April
25.0
20.4
Date
-29-
Salinity
o/oo
Temperature
°C
1 May
38.7
24.3
15 May
37.5
24.8
Date
Table 17
6
6
Shrimp Landings (lb x 10 ) and Value ($ x 10 )
BROWN SHRIMP
Year
1962
1963
1964
1965
1966
1967
1968
1969
1970
1971
1972
1973
1974
TEXAS LANDINGS
Lbs.
Value
24.5
31.3
25.9
34.3
33.9
55.5
37.0
29.8
41.6
43.8
48.3
33.4
3X-5
5
GULF LANDINGS
Lbs.
Value
SOUTH ATLANTIC
Lbs.
Value
19.7
19.3
16.7
22.2
30.3
39.3
33.1
29.5
36.9
52.0
62.8
59.2
48.8
41.4
56.0
42.2
62.4
64.0
100.9
78.9
65.8
80.9
87.6
90.0
58.9
62.4
30.0
29.1
23.6
35.5
48.2
60.6
56.8
51.1
59.4
81.7
100.7
89.9
72.3
7.2
4.7
4.4
5.0
7.2
4.9
3.7
6.0
4.4
4.8
2.4
2.6
2.9
5.9
3.0
3.3
5.6
3.9
_
-
4.8
2.7
6.9
5.5
4.6
6.1
4.9
4.8
7.1
5.7
6.3
5.0
23.1
47.1
44.0
33.6
29.9
24.9
30.9
43.6
46.0
41.9
37.9
34.1
31.4
14.7
19.9
24.2
19.1
21.5
18.4
24.9
36.3
35.3
41.6
44.7
53.0
39.7
7.9
4.7
5.3
5.9
7.1
5.6
2.6
3.4
6.7
4.7
5.3
11.0
11.0
10.0
10.2
*
TOTAL LANDINGS
Value
Lbs.
48.6
60.7
46.6
67.5
71.2
105.9
82.6
71.0
85.4
93.8
94.8
61.7
69.3
33.7
31.6
26.2
38.5
54.1
63.9
60.1
56.4
63.3
88.4
106.3
94.6
78.4
31.0
51.8
49.2
44.2
35.9
32.0
41.9
55.7
54.1
54,2
48.7
46.0
40.1
20.3
22.5
27.6
25.8
26.2
23.7
34.9
46.5
42.3
55.0
57.2
73.8
50,7
WHITE SHRIMP
1962
1963
1964
1965
1966
1967
1968
1969
1970
1971
1972
1973
1974
*
No Data
7.0
8.9
12.0
9.2
7.8
6.4
12.5
12.0
12.4
9.2
11.4
14.9
11.5
10.1
10.8
10.2
11.1
15.2
23.0
16.1
10.6
8.1
7.0
-
-
10.8
11.8
8.7
12.6
20.7
11.0
Table 18,
Annual shrimp catches, calculated catch per-unit-ef fort values and calculated
number of effort units from Sabine Lake, Texas and Calcasieu Lake, Louisiana (19621973)
Season
Catch (lb)
Calcasieu
Lake
Catch per-unitEffort (lb/dayXh
Calcasieu
Sabine
Lake
Lake
a
Sabine
Lake
Number of Effort
Units (days)c
Calcasieu
Sabine
Lake
Lake
BROWN SHRIMP
1962
1963
1964
1965
1966
1967
1968
1969
1970
1971
1972
1973
244,258
65,603
48,288
112,757
130,799
441,200
223,874
284,914
582,439
520,854
775,562
237,234
24,207
105,603J
612.8
1,562.2
211.0
160.4
967.4
311.4
1,718.4
459.3
928.9
1,117.2
632.8
1,167.2
1,002.5
324.6
264.8
452.9
469.9
517.8
293.7
113.4
577.2
935.5
776.7
596.9
413.3
317.9
440.6
738.1
202.3
136.5
388.1
962.4
260.7
333,4
2,185.1
169.0
921.8
332.2
711.3
1,276.4
344.4
851.8
660.6
619.3
625.8
2,346.0
364.0
465.4
263.7
87.7
124.0
70.3
61.2
72.9
_
_
_
_
252.5
210.7
28.1
245.5
140.8
394.9
353.8
244.1
581.1
1,604.6
_d
9,389
1,700
3,133
2,079
1,060
4,714
3,160
39.5
67.6
-
23.5
27.7
24.7
15.1
-
-
399.5
61.4
126.8
137.7
-
22.3
19.7
WHITE SHRIMP
1962
1963
1964
1965
1966
1967
1968
1969
1970
1971
1972
578,612
76,549
433,162
172,069
208,915
144,746
198,809
796,843
513,103
369,684
681,282
1Q7-*
«■»?
&*■*
258,639
745,803
160,506
343,511
53,338
11,977
48,125
67,690
15,951
24,291
6,059
_
a/ Gulf Coast Shrimp Data, Annual Summaries 1962-1973. U.S. Department of Interior
(1962-1968), U.S. Department of Commerce (1969-1973).
b/
Catch per 24 hour fishing period.
c/
Obtained by dividing total annual catch by catch per-unit-effort.
d_/ None reported.
-31-
Table 19
Annual shrimp catches, calculated catch per-unit-effort values and calculated
number of effort units from the Gulf off Sabine Lake, Texas and Calcasieu Lake,
Louisiana (1962-1973).
Season
Catch (lb)
(x 103)
Catch per-unit~
effort (lb/day)b
Number of effort
units (days)c
BROWN SHRIMP
1962
1963
1964
1965
1966
1967
• 1968
1969
1970
1971
1972
1973
99.4
443.6
453.0
2,006.2
1,466.2
3,466.6
2,325.6
1,768.8
3,485.6
4,858.9
3,769.6
1,567.9
42.3
148.8
84.3
327.3
219.6
667.1
457.0
224.6
490.0
437.6
509.8
229.3
2,349.9
2,961.3
3,024.0
6,129.5
6,676.7
5,196.5
5,088.8
7,875.3
7,113.5
11,103.5
7,394.3
6,837.8
WHITE SHRIMP
1962
1963
1964
1965
1966
1967
1968
1969
1970
1971
1972
1973
1,952.4
2,980.4
3,250.2
2,624.0
2,408.0
1,954.7
1,788.1
2,908.7
2,933.5
3,698.6
3,624.5
4,284.2
489.3
674.1
489.8
348.8
374.6
201.1
429.2
215.3
232.8
147.6
252.1
269.4
3,990.2
4,421.3
6,635.8
7,522.9
6,428.2
9,720.0
4,166.1
13,509.9
12,600.9
25,058.3
14,377.2
15,769.1
f/
Gulf Coast Shrimp Data, Annual Summaries 1962-1973. U.S. Department of
Interior (1962-1968); U.S. Department of Commerce (1969-1973).
VJ
Catch (heads-off) per 24 hour fishing period.
2J
Obtained by dividing catch by (heads-off) per unit-effort.
-32-
^"~
Sabine
Lake
^- Galveston Bay
TEXAS
GULF of MEXICO
Figure 1. Texas Coast
-33-
Galveston Bay Stations
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
16.
17.
18.
Sylvan Beach
Morgan's Point
Upper Galveston Bay
Red Bluff
Trinity Reef
Double Bayou
Trinity Bay
Vingtune I.
East Bay
Bolivar
West Bay
West Bay
Texas City Dike
Dickinson Bayou
Moses Lake
Jones Lake
Chocolate Bay
Clear Lake
A) Galveston Bay
Matagorda Bay
1.
2.
3.
4.
5.
6.
Lavaca Bay
Tres Palacios River
Carancahua
Colorado R.
Mad Island
Palacios Channel
B) Matagorda Bay
Aransas Bay
1.
2.
3.
4.
5.
Fulton Beach
Ranchhouse Area
LBJ Causeway
Marker 37-43
Marker 25-31
C) Aransas Bay
Figure 2. Coastal bays and stations sampled in summer and fall
(1972)
-34-
50 r
»m *
25
Tertiary Bays
Secondary Bays
Primary Bays
1 April
0
25
8 April
25
15 April
0
& 25
1
•H
M
,C
to
23 April
0
iw
O
M
(1)
25
2
0)
W>
0
• «'
1 May
rt
M
0)
>
<!
25
8 May
25
15 May
23 May
25
-£+-
0 Iff
13
33
-=* ■ .. crrry
53
73
JL+±
93
108
Length (midpoint of 5 mm intervals)
Figure 3. Length-frequency distributions of brown shrimp,
Galveston Bay (1974).
-35-
0,.
Tertiary Bays
Secondary Bays
Primary Bays
• •
25
1 April
25
8 April
«
.»
25
15 April
•» .
•
I
•
•
•
»i
25
23 April
25
1 May
25
8 May
25
15 May
u
w
<4-l
o
u
(U
cd
u
3
s *~
.-'"..
0
*• * •
25
*
•
#
23 May
•
0
?.
13
33
53
1 ..
73
ft
93
1
133
Length (midpoint of 5 mm intervals)
Figure 4. Length-frequency distributions of brown shrimp,
Matagorda Bay (1974).
-36-
25
...
Tertiary Bays
Secondary Bays
Primary Bays
1 April
8 April
***«
• .«
•
*• » a
•1
15 April
•«•
23 April
.*
^
^
1 May
25
25
u
m
o
15 May
M
0)
25
60
2
23 May
125
100
13
33
53
73
103
123
133
Length (midpoint of 5 mm intervals)
Figure 5. Length-frequency distribution of brown shrimp,
Aransas Bay (1974).
-37-
«•«
____
Bar seine stations (nursery areas)
Trawl stations (secondary bays)
1 April
15 April
15 May
OHM
13
23
33
43
53
63
73
83
93
Length (midpoint of 5 mm intervals)
Figure 6.
Length-frequency distribution of brown
shrimp, Lower Laguna Madre (1974).
-38-
l,100r-
11
Brown Shrimp
1,000-
10
f- Catch
800-
"8
600-
T3
x> 400
CO
CB
T3
2
200
vO
o
1-1
X
A
i-i
00
o
<u
n-i
0)
i
4J
•H
(3
.C
z
cd
White Shrimp
y
o
J
300
rH
«
4-1
O
H
I
M
0)
■a
4->
CO
a
200
100
0
1962
1964
1966
1968
1970
1972 1973
Year
Figure 7.
Comparison of shrimp catch per day fished with total
annual catches (sub-area 18) using data published
in Gulf. Coast Shrimp Data.
-39-