(DRAFT) - Taxonomy
Species mullet, striped
Species Id M010010
Date 26 AUG 96
TAXONOMY
NAME - mullet, striped
OTHER COMMON NAMES - striped mullet, grey mullet and black mullet
ELEMENT CODE -
CATEGORY - Fish
PHYLUM AND SUBPHYLUM - Chordata,
CLASS AND SUBCLASS - Osteichthyes,
ORDER AND SUBORDER - Perciformes,
FAMILY AND SUBFAMILY - Mugilidae,
GENUS AND SUBGENUS - Mugil,
SPECIES AND SSP - cephalus,
SCIENTIFIC NAME - Mugil cephalus
AUTHORITY - Linnaeus, 1758
TAXONOMY REFERENCES - 47
Taxonomy - 1 (DRAFT) - Status
Species mullet, striped
Species Id M010010
Date 26 AUG 96
STATUS
Coded Status
Sport Fish
Game (Consumptive Recreational)
Commercial
Commercial/consumption
Commercial/bait
REFERENCES FOR STATUS - 47
COMMENTS ON STATUS -
Striped mullet along the Florida gulf coast are used as bait for a wide
variety of fishes and are regarded as an excellent food fish.*47*
-See C.Econ.Val for more information.
Status - 1 (DRAFT) - Distribution
Species mullet, striped
Species Id M010010
Date 26 AUG 96
DISTRIBUTION
Distribution - 1 HABITAT ASSOCIATIONS
NATIONAL WETLAND INVENTORY CODES
NWI NWICLS NWIMOD NWISPEC
Marine
Marine
Estuarine
Riverine
Palustrine
Palustrine
REFERENCES FOR NWI - 47
COMMENTS ON HABITAT ASSOCIATIONS -
-see C.Aquat.Hab
Habitat Associations - 1 (DRAFT) - Food Habits
Species mullet, striped
Species Id M010010
Date 26 AUG 96
FOOD HABITS
TROPHIC LEVEL -
OMNIVORE
REFERENCES FOR TROPHIC LEVEL - 47
LIFESTAGE FOOD FOOD PART
Larva Zooplankton Not Applicable
Juvenile Copepods Not Specified
Juvenile Diptera Not Specified
Adult Detritus - Inorganic Not Applicable
Adult Chlorophyta Not Applicable
Adult Bacillariophyceae Not Applicable
General Detritus - Organic Not Applicable
General Microcrustaceans Not Applicable
REFERENCES FOR GENERAL FOOD - 47
REFERENCES FOR ADULT FOOD - 47
REFERENCES FOR JUVENILE FOOD - 47
COMMENTS ON FOOD -
Mullet are primary consumers that feed largely on relatively minute living
and dead vegetable matter. They are an ecologically important component in
the flow of energy through estuarine communities. Mullet commonly feed by
sucking up the top layer of sediment, which is rich in detritus and
microalgae, primarily diatoms in the the Cedar Key area, and by grazing on
epiphytes and epifauna from seagrasses and other substrates. They also
ingest surface scum when large concentrations of microalgae are present at
the air-water interface and feed on swarming polychaetes (nereis succinea)
in the water column. In some freshwater habitats striped mullet feed
primarily on the epiphytes and epifauna of aquatic macrophytes and on
benthic filamentous green algae, but they also ingest sediment for
trituration (grinding). The time of most intense feeding apparently varies
with location.*47*
COMMENTS ON ADULT FOOD -
Adult striped mullet have been described as herbivorous, detrivorous, and
"interface" feeders. The diet and feeding behavior of mullet may vary by
location, but their major food is either epiphytic and benthic microalgae,
macrophyte detritus, or inorganic sediment particles. Although sediment
particles function as a grinding paste in the gizzard-like pyloric portion
of the stomach, some small particles are rich in adsorbed micro-organisms
and are selectively ingested for their food value.*47*
COMMENTS ON JUVENILE FOOD -
There has been some discrepancy concerning the diet of juvenile striped
mullet but most authors now agree that larval mullet primarily eat
microcrustaceans. The fact that larvae, successfully reared to 20 mm SL,
were fed entirely on animal material illustrates the dependence of larval
Food Habits - 1 (DRAFT) - Food Habits
Species mullet, striped
Species Id M010010
Date 26 AUG 96
and postlarval mullet on zooplankton. In Florida's Indian River lagoon the
stomach contents of nearly 400 striped mullet larvae up to 35 mm SL were
examined. Larvae up to 15 mm SL fed almost entirely on copepods (70%) and
mosquito larvae (30%); those from 15 to 25 mm SL fed on copepods (50%),
mosquito larvae (15%), and plant debris (35%); and larvae from 25 to 35 mm
SL fed primarily on plant debris (80%) and copepods (10%). The proportion
of sand and detritus in the gut of juveniles increases with length,
indicating that they tend to take more food from the bottom as they grow
older. The exceptions are juveniles that feed from the water column or
surface when suitable foods are plentiful there.*47*
COMMENTS ON LARVAE FOOD -
-see C.Food.J
Food Habits - 2 (DRAFT) - Environment Associations
Species mullet, striped
Species Id M010010
Date 26 AUG 96
ENVIRONMENTAL ASSOCIATIONS
G = General A = Adult
LIM = Limiting RA = Resting Adult
J = Juvenile FA = Feeding Adult
RJ = Resting Juvenile BA = Breeding Adult
FJ = Feeding Juvenile P = Pupae
L = Larvae E = Egg
RL = Resting Larvae
FL = Feeding Larvae
LIFESTAGE ENVIRONMENTAL ASSOCIATIONS
L
E
A
A
A
A
A
A
A
G Water Depth Preference: Specified in Comments
L Dissolved Oxygen: Specified in Comments
G Dissolved Oxygen: Specified in Comments
E Dissolved Oxygen: Specified in Comments
G Water Temperature: Specified in Comments
REFERENCES FOR ENVIRONMENTAL ASSOC_ - 47
REFERENCES FOR FEEDING ADULT ENVIRONMENTAL ASSOC_ - 47
REFERENCES FOR FEEDING LARVAE ENVIRONMENTAL ASSOC_ - 47
REFERENCES FOR EGG ENVIRONMENTAL ASSOC_ - 47
COMMENTS ON ENVIRONMENTAL ASSOCIATIONS -
Temperature:
An analysis of the worldwide distribution of striped mullet suggests that
mullet are not permanent residents in waters with temperatures below 16
degrees C or where water temperatures fail to reach 18 degrees C. On
Florida's gulf coast, young mullet live in salt marsh pools at
temperatures from 13 to 34.5 degrees C. Water temperatures probably
regulate the length of time that young mullet stay in estuaries. Mullet
less than 50 mm SL prefer temperatures from 30.0 to 32.5 degrees C. and
mullet from 50 to 130 mm SL prefer temperatures from 19.5 to 20.0 degrees
C. For all sizes of fish the temperature selected tends to decrease as
salinity increases.*47*
Salinity:
Adult mullet have been reported from waters with a salinity ranging from 0
ppt to 75 ppt. Using fish induced to spawn in the laboratory, egg survival
Environment Associations - 1 (DRAFT) - Environment Associations
Species mullet, striped
Species Id M010010
Date 26 AUG 96
was found to be highest at a salinity of 32 ppt (the highest salinity
tested), whereas the greatest survivial of larvae was at 26 ppt in tests
from 24 to 36 ppt. When juvenile mullet are 40-70 mm Sl they reach a
definitive state of osmoregulatory capability and can tolerate salinities
from freshwater to full seawater.*47*
Dissolved Oxygen:
Mullet larvae apparently cannot survive in dissolved oxygen (DO)
concentrations below 4 ppm. Over a range of 1.0 to 8.0 ppm DO, eggs
incubated in the laboratory for 48 h had a survivial rate of 0%-3% at
concentrations 4.5 ppm and below, and 85%-90% for 5.0 ppm and above.
Larvae were held from one to four days in concentrations of 4.0-7.9 ppm DO,
and those held for 4 days had a mean survival of 0-8% at 7.9 ppm. Although
7.9 ppm in this instance is 146% saturation, there was no evidence of gas
bubble disease. No specific data on oxygen requirements were found for
adult mullet, but preliminary experiments with caged fish show that they
survive at an oxygen concentration of 4.4 ppm DO at 29 degrees C and a
salinity of 28 ppt. In a study of schools of migrating mullet, DO was 29%
lower at the trailing than the leading edges, suggesting that the continual
breaking up and reforming of the school and changing of position within the
school allow fish at the center and trailing edge access to water higher in
DO.*47*
Depth:
Mullet live in a wide range of habitats and depths and spawn primarily in
relatively deep cool coastal waters. The larvae move inshore to shallow
waters along beaches and in salt marshes. In Hawaii, schools of mullet
less than 50 mm SL were always found in waters of minimal depth, including
the swash zone and tide pools, despite near-lethal temperatures. Juveniles
greater than 50 mm SL prefer slightly deeper waters vacated by smaller
mullet. The preference of fish less than 50 mm SL for extremely shallow
water apparently permits them to escape most predators and to feed without
serious competition.*47*
COMMENTS ON FEEDING LARVAE ENVIRONMENTAL ASSOC_ -
-see C.Environ
COMMENTS ON EGG ENVIRONMENTAL ASSOC_ -
-see C.Environ
Environment Associations - 2 (DRAFT) - Life History
Species mullet, striped
Species Id M010010
Date 26 AUG 96
LIFE HISTORY
Morphology/Identification Aids:
Dorsal fin IV + I spines, 8 soft rays; anal fin III spines, 8 rays (II, 9
in juveniles); pectoral fin 16-17 rays; caudal fin 18-20 rays; lateral
scale count 38-42. Anal and second dorsal fins almost scaleless; origin of
second dorsal behind origin of anal fin ; pectoral fin shorter than
distance from last spine of first dorsal to origin of second dorsal fin;
head somewhat wider than deep; mouth terminal and small, teeth
inconspicuous; no lateral line visible, but longitudinal dark stripes on
the sides of elongate body; body bluish-gray dorsally and white ventrally;
scales cycloid in young, feebly ctenoid in adults; distinct axillary scale
at pectoral fin; gill raker number increasing with size; prominent adipose
eyelid with only a narrow slit over the pupil, covering the preorbital
anteriorly and running twice as far behind the eye as in front. The six
Mugil species reported from south Florida sometimes are difficult to
separate taxonomically; however a key that is useful for tentative
identification has been constructed. The two species most often
encountered, striped mullet and white mullet, may be separated by anal fin
ray counts of 8 and 9 respectively.*47*
Spawning:
Because of the scarcity of data on striped mullet spawning, speculations on
the locations of spawning grounds are based largely on the appearance of
larvae. Mullet have been reported to spawn inshore, along beaches, 8 to 32
km offshore, and in water deeper than 40 m. In the Gulf of Mexico, mullet
were observed spawning 65 to 80 km offshore in water 1,000 to 1,800 m deep.
These observations indicate that mullet spawn over a wide range of coastal
waters but the current consensus is that most spawn offshore.
The spawning season of striped mullet usually begins in October, peaks in
November-December, and ends in February. The estimated fecundity of striped
mullet is 0.5 to 2.0 million eggs per female, depending on the size of the
female.
Eggs:
Eggs are transparent, straw-colored, non-adhesive, spherical, and without
external marking. The eggs average 0.72 mm in diameter, contain an oil
globule 0.28 mm in diameter, are positively buoyant, and hatch about 48 h
after fertilization.*47*
Larvae:
Larvae average 2.4 mm long at hatching and have no mouth,, paired fins, or
branchial skeleton. After 5 days they are about 2.8 mm long, the jaws are
well-defined, the internal organs become organized, and fin buds have
started developing. Morphological and meristic development and growth
continue until the larvae are about 16-20 mm standard length (SL), at which
time they migrate to inshore waters and estuaries. The migrant larvae have
two spines and nine rays in the anal fin (the "Querimana" stage) until they
reach 35-45 mm SL, at which time the first ray fuses into a third spine and
the adipose eyelid becomes apparent. The mullet is then considered a
juvenile.
Life History - 1 (DRAFT) - Life History
Species mullet, striped
Species Id M010010
Date 26 AUG 96
Juveniles:
Juvenile striped mullet 40 to 69 mm SL reach a "definitive state" of
osmoregulatory capability. For example, they tolerate salinities of 0 to 35
ppt, whereas they could not have previously survived in freshwater.
Juveniles spend the rest of their first year of life in coastal waters, salt
marshes, and estuaries, and often move to deeper water in the fall when the
adults migrate offshore to spawn, yet large numbers of immature mullet
overwinter in estuaries. After the first year, mullet inhabit the sea, salt
marshes, estuaries or freshwater rivers. Apparently in some instances,
females greatly outnumber the males in brackish and freshwater habitats.*47*
Adults:
The length at which mullet mature ranges from about 200 to 300 mm SL; the
females mature at a slightly larger size than the males. Although some
mature in their second year of life, most mature in their third year.
Mullet may live 4 years or more; the maximum age reported is 13 years.
Mature mullet migrate offshore to spawn in the fall and winter, often in
large schools. Mullet that mature in freshwater either migrate to the sea
to spawn or resorb their gonads. Swimming speed during migration is much
greater than that predicted to be energetically optimal, probably because of
the increased hydromechanical efficiency provided by schooling and the
selective force of heavy predation during spawning migrations. Fishing for
mullet is heaviest during spawning migration when schools are large, the
condition of the fish is excellent, and the prized roe (gonads) are largest.
In a mullet tagging study, 2,779 recoveries from 12,647 tagged mullet
revealed that 91% were recovered within 32 km of the release point; only 2%
were recovered more than 160 km away.
Growth Characteristics:
Growth rates of striped mullet along the gulf coast of Florida increase from
west to east along the panhandle and to the south along the peninsula,
possibly due to a slight increase in coastal water temperatures. In a
tagging study, growth during spring and summer was twice that of fall and
winter.
Females are larger and grow slightly faster than males of the same age. In
the Gulf of Mexico, the growth in length of mullet gradually slows as the
fish become larger, and reaches an asymptote at an average length of 600 mm
TL, at probably 5-6 years of age.*47*
Predation and Competition:
The major predators of juvenile and adult mullet are fishes and birds. In
Florida, sharks sometimes feed heavily on large mullet. Mullet up to 35 cm
long are fed on by spotted seatrout (Cynoscion nebulosus). Although the
diet of striped mullet overlaps those of a variety of aquatic species,
competition has not been documented.
Parasites:
Parasitic infections and infestations are common in mullet. Of nearly 300
adult mullet from freshwater and saltwater sites on Florida's gulf coast, no
individuals were found without parasites on either the gills or body
surface. Striped mullet serve as definitive or intermediate hosts for many
Life History - 2 (DRAFT) - Life History
Species mullet, striped
Species Id M010010
Date 26 AUG 96
parasites including flagellates, ciliates, myxosporidians, monogenean and
digenean trematodes, nematodes, acanthocephalans, leeches, argulids,
copepods, and isopods. Extensive parasite-induced mortalities of mullet in
the wild have not apparently been reported.*47*
LIFE HISTORY CODES -
Foraging Strategy: Grazing
Breeding/Spawning Season: October
Breeding/Spawning Season: November
Breeding/Spawning Season: December
Breeding/Spawning Season: January
Breeding/Spawning Season: February
Average Number of Offspring/Reproductive Effort: Grea
REFERENCES FOR LIFE HISTORY- 47
Life History - 3 (DRAFT) - Management Practices
Species mullet, striped
Species Id M010010
Date 26 AUG 96
MANAGEMENT PRACTICES
RESULT MANAGEMENT PRACTICE
Existing Regulating harvest - setting size limits
Beneficial
Beneficial Developing/maintaining/protecting wetlands
REFERENCES FOR BENEFICIAL MANAGEMENT PRACTICES - 47
REFERENCES FOR EXISTING MANAGEMENT PRACTICES - 47
COMMENTS ON MANAGEMENT PRACTICES -
Management:
Closed seasons and other regulations have been used to manage the Florida
mullet in the past, but most have since been eliminated. Currently, minimum
lengths of 9 to 11 inches FL (depending on local ordinances) are the only
regulations. Although landings and fishing intensity for striped mullet
declined from 1964 to 1977, catch-per-unit-of-effort and the average size
of the fish remained unchanged. This relationship suggests that the lack of
demand rather than a scarcity of mullet limits the fishing.*47*
Sport Fishery:
Striped mullet along the Florida gulf coast are used as bait for a wide
variety of fishes and are regarded as an excellent food fish. In fresh and
brackish waters, mullet are sometimes caught with hook and line. Earthworms
may be used for bait, but oatmeal and chicken laying mash are more popular.
Mullet from freshwater often have a muddy or hydrogen sulfide-like taste.
In brackish and saltwater areas, mullet are sometimes snagged with treble
hooks, but most often some type of net is used. Sport fishermen usually
use a cast net or seine, but some use short lengths of gill nets or trammel
nets.*47*
Commercial Fishery:
In general, sport and commercial mullet fishermen employ the same types of
nets, but commercial seines, gill nets, and trammel nets are usually much
longer. Seines are now used more on the east coast than on the west coast
because of the abundance of smooth bottoms near sandy beaches on the east
coast. Nets with largest meshes are used in the fall when mullet are gravid
and fat. Many gill nets and trammel nets are longer than 500 m and are
usually set from a boat. When mullet are in open water either net is set to
completely encircle the school; when the school is near a shoreline the net
is set in a half-circle from shore to shore; and in intertidal coves or
creeks the nets are used to completely block off an area, catching the
mullet as they leave with the ebb tide. Fishing may be carried out day or
night, and sometimes two boats work together, combining their nets and
encircling a school from opposite directions. When seines or nets are used,
many mullet escape by jumping over the float line and, in the case of gill
and trammel nets, they may avoid the net. Small mullet escape through the
mesh.*47*
Importance of Maintaining Habitat:
Management Practices - 1 (DRAFT) - Management Practices
Species mullet, striped
Species Id M010010
Date 26 AUG 96
Striped mullet are an ecologically important component in the flow of energy
through estuarine communities. Larvae migrate to inshore waters and
estuaries. Juveniles spend the rest of their first year of life in coastal
waters, salt marshes, and estuaries, and often move to deeper water in the
fall when the adults migrate offshore to spawn, yet large numbers of
immature mullet overwinter in estuaries. After the first year, mullet
inhabit the sea, salt marshes, estuaries, or freshwater rivers.*47*
Management Practices - 2 (DRAFT) - References
Species mullet, striped
Species Id M010010
Date 26 AUG 96
References
47* Collins, M. 1985. Species Profiles: Life Histories and
Environmental Requirements of Coastal Fishes and Invertebrates
(South Florida)--Striped Mullet. U.S. Fish and Wildlife Service
Biol. Rep. 82(11.34) pp 11.
References - 1