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Species Description:
Both marine catfishes (Ariidae)
and freshwater catfishes (Ictaluridae) are notable for their unscaled
skin, forked caudal fins, adipose fins set anterior to the caudal
peduncle, and the presence of large, serrated spines positioned
anterior to the dorsal fin and the pectoral fins. Marine catfishes
are separated from Ictalurids based on the absence of barbels on
the nostrils, and by their body color, which is typically steel
blue dorsally, fading to silver laterally, and white ventrally.
Bagre marinus, the gafftopsail catfish,
is an elongate marine catfish that reaches 57.1 cm (22.4 inches)
in length (Jones et al. 1978). There is a single dorsal fin having
1 strong, serrated spine and 7 soft rays. The first ray of the dorsal
and pectoral fins have extended, white filaments equal to or exceeding
the length of the dorsal spine. The anal fin has 22-28 rays. The
pectoral fins have 1 spine and 11-14 rays, and the ventral fin has
6 rays. There is a distinctive V-shaped indentation on the posterior
margin of the anal fin.The head is slightly depressed, with the
mouth inferior. Three pairs of barbels are present, one pair on
the maxilla and 2 pairs set under the chin. The maxillary pair of
barbels are elongate and reach nearly to the ventral fins, which
are set well behind the dorsal fin. The adipose fin is tipped in
black, while the remainder of the fins are pale to dusky in color.
Females have larger pelvic fins than males (Lee 1937;Merriman 1940;
Muncy and Wingo 1983).
II. HABITAT AND DISTRIBUTION
Regional Occurrence:
Bagre marinus ranges from Cape Cod, Massachusetts south
through coastal Florida and the Gulf of Mexico to Panama (Muncy
and Wingo 1983).
IRL Distribution:
Bagre marinus is common throughout the IRL.
III. LIFE HISTORY AND POPULATION
BIOLOGY
Age, Size, Lifespan:
The maximum reported size for
Bagre marinus was 69.0 cm (27.2 inches) total length (TL),
with a maximum reported weight of 4.4 kg (9.7 pounds) (IGFA 2001).
Reproduction:
Bagre marinus females caught on the Gulf coast of Alabama
had well-developed oocytes beginning in April (Swingle 1971). Gafftopsail
catfishes spawn repeatedly over an approximately 10 day period from
May - August in inshore mudflats (Jones et al 1978). Eggs are passed
to, or picked up by, males, who incubate and brood them in their
mouths for 60 - 80 days (Gunter 1947; Ward 1957).
Embryology:
Eggs are large at fertilization, measuring 15-26 mm (0.6 - 1.02
inches) in diameter (Merriman 1940) and are gold to yellow in color.
Parental care by males offsets low fecundity of females, which have
only 20 - 65 eggs per spawning event (Merriman 1940; Ward 1957;
Jones et al. 1971). Numerous small, non-functioning eggs are often
found attached to large, viable eggs. Gunter (1947) speculated that
these smaller eggs might be utilized as a food source for males
brooding offspring.
Eggs of Bagre marinus are brooded
in the mouth of males and hatch within 42 -70 days when held under
laboratory conditions (Jones et al 1971). Larvae measure 45-78 mm
(1.77 - 3.07 inches) TL at hatching and are retained in the mouths
of male parents until their yolk sacs are absorbed approximately
2-4 weeks after hatching. Adult characteristics are present at absorption
of the yolk sac but juveniles tend to remain with the parent, retuning
to its mouth for protection, for a short time thereafter.
Juveniles measure 80-100 mm (3.15 - 3.94 inches)
TL.
IV. PHYSICAL TOLERANCES
Temperature:
Juveniles are reported to prefer water temperatures of 16-30 °C
(61 - 86 °F)
(Muncy and Wingo 1983). Juneau (1975) reported juveniles in Vermillion
Bay, Louisiana during summer and fall when water temperatures ranged
between 20.4 - 30.5 °C
(69 - 87 °F).
Adult gafftopsail catfishes prefer
water temperatures of above 25 °C
(77 °F)
(Perret et al. 1971). They avoid low
temperature waters in the winter months by migrating offshore where
water temperatures are more stable, returning to inshore areas in
the spring.
Salinity:
Juveniles have no specific salinity preferences, and are found in
waters of 0-31 parts per thousand (ppt). Adults have been reported
to inhabit fresh water areas, but tend to be more common where salinity
ranges from 5 - 30 ppt (Perret et al. 1971; Jones et al. 1978).
V. COMMUNITY ECOLOGY
Trophic Mode:
Sea catfishes
are opportunistic feeders that utilize mud and sand flats as feeding
grounds. Algae, seagrasses, cnidarians, sea cucumbers, gastropods,
polychaetes, shrimps, crabs, and other fishes comprise the bulk
of the diet (Merriman 1940).
Males carrying
eggs or juveniles do not feed (Muncy and Wingo 1983).
Habitats:
Though Bagre marinus has has been reported in freshwater
locations (Muncy and Wingo 1983), most juveniles leave estuarine
areas for offshore waters in the winter months, but return to bays
and estuaries from May - June, prior to spawning (Gunter 1938).
Trawl surveys in the estuaries of Mississippi, Alabama, Louisiana
and Texas reveal that 10 - 100 times fewer juvenile gafftopsail
catfishes are captured inshore than are sea catfishes (Hoese et
al 1968; Perret et al. 1971; Swingle 1971; Franks et al. 1972; Barrett
et al. 1978). Juneau (1975) reported Bagre marinus
inhabits estuaries in Louisiana primarily throughout the summer
and fall months.
Depth preferences of gafftopsail
catfishes are apparently related to bottom type and to water temperature,
with higher abundances noted when there is ample organic debris
in substrates and water temperatures are above 15 °C
(Muncy and Wingo 1983).
Activity Time:
Gunter (1938) and Jones et
al. (1978) reported that catfishes sometimes school nocturnally.
VI. SPECIAL STATUS
Special Status:
Limited commercial and recreational importance.
Fisheries Importance:
COMMERCIAL
FISHERY:
Though edible, the gafftopsail catfish is not generally consumed
as a food fish, with many commercial and sport fishers regarding
it as a nuisance species due to its dorsal and pectoral spines,
which are large, serrated, and capable of causing painful wounds
(Muncy and Wingo 1983). However, gafftopsail catfishes do have limited
commercial importance and are harvested for industrial purposes
in commercial bottom trawling operations (Muncy and Wingo 1983).
From
1987 - 2001, 1.04 million pounds of marine catfishes (including
both the sea catfish, Ariopsis felis, and Bagre marinus,
the gafftopsail catfish) were harvested commercially in the 5-county
area (Volusia, Brevard, Indian River, St. Lucie, Martin) encompassing
the Indian River Lagoon. The harvest was valued at $777,497, which
ranks marine catfishes thirty-fifth in dollar value to IRL counties,
and forty-second in pounds harvested.
Figure 1 below shows the
dollar value of the commercial fishery of catfishes to IRL counties
by year. As shown, the commercial catch ranged from a low
of $9,167 in 1989 to a high of over $344,931 in 1992. Martin
County accounted for the largest percentage of the marine catfish
harvest with 32.8% in total (Figure 2), followed by St. Lucie
County, which accounts for 21.5% of the total. Brevard, Volusia,
and Indian River Counties accounted for 19.1%, 16.9% and 9.7% of
the total respectively. Interestingly, the six-year period
between 1990 - 1995 accounts for 87% of the total harvest of catfishes
in the vicinity of the IRL. Of note is that 44% of the cumulative
harvest for the entire period between 1987 - 2001 occurs in 1992,
a clearly anomalous year. Martin County again accounts for the bulk
of the harvest in 1992, however, the other 4 IRL Counties also saw
greatly increased catches of catfishes in this year.
Figure
1. Annual dollar value of the commercial catch of marine catfishes
(sea catfish and gafftopsail catfish) to the 5-county area of the
Indian River Lagoon.
Figure 2. Total marine catfish (sea catfish and gafftopsail
catfish) dollar value and percentage by county for the years 1987
- 2001.
Table 1. Total dollar value
of IRL marine catfishes, Ariopsis felis and Bagre marinus, between
1987 - 2001.
Table 2. By-county annual
and cumulative percentages of the marine catfish (sea catfish and
gafftopsail catfish) harvest for the years 1987-2001.
Table 3. By-county cumulative
dollar value and percentage of total for the marine catfish (sea
catfish and gafftopsail catfish) harvest from 1987 - 2001.
RECREATIONAL FISHERY:
Though
the gafftopsail catfish is considered a nuisance species by many,
between 1997 - 2001 recreational anglers in the IRL harvested 46,755
gafftopsail catfishes, ranking it fortieth among the most harvested
IRL species. It was also captured
from other inshore waters, nearshore waters and offshore waters
around the IRL. The information below reflects angler survey information
taken from the 5-county area that encompasses the Indian River Lagoon.
Approximately 317,024 gafftopsail catfishes were harvested in east
central Florida between 1997 - 2001. The bulk of the recreational
harvest (45.5%), was taken in nearshore waters to the 3-mile state
territorial limit. Inland waters other than the IRL account for
38.9% of the harvest, while the IRL accounts for14.7%, and offshore
waters to the 200-mile federal limit account for only 0.9% of the
catch.
Figure 3. Survey data for
the gafftopsail catfish recreational fishery showing the number
of fishes harvested in East Florida waters from 1997 - 2004.
Figure 4. Summary of the
gafftopsail catfish recreational harvest and percentage of total
by area from 1997 - 2004.
Table 4. Summary data for recreational fishery in Eastern
Florida waters for the gafftopsail catfish, Bagre marinus, from
1997 - 2004. Data provided by National Marine Fisheries
Service, Fisheries Statistics Division, NOAA.
Table 5. By-county annual and cumulative percentages of the
gafftopsail catfish harvest for the years 1997 - 2001.
Data provided by National Marine
Fisheries Service, Fisheries Statistics Division, NOAA.
Table 6. Summary of the gafftopsail catfish recreational harvest
and percentage of total fish captured in each area from 1997 - 2004.
Data provided by National Marine Fisheries Service, Fisheries Statistics
Division, NOAA.
VII.
REFERENCES
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of selected finfish and shellfish in Mississippi Sound and adjacent
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Gunter, G. 1938. Seasonal variations in abundance
of certain estuarine and marine fishes in Louisiana with particular
reference to life histories. Ecol. Monogr. 8(3):313-346.
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Report by:
K. Hill, Smithsonian Marine Station
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