(DRAFT) - Taxonomy
Species marlin, blue
Species Id M010409
Date 26 AUG 96
TAXONOMY
NAME - marlin, blue
OTHER COMMON NAMES - marlin
ELEMENT CODE -
CATEGORY - Fish
PHYLUM AND SUBPHYLUM - Chordata,
CLASS AND SUBCLASS - Osteichthyes (Bony Fishes),
ORDER AND SUBORDER - Perciformes,
FAMILY AND SUBFAMILY - Istiophoridae (Billfishes),
GENUS AND SUBGENUS - Makaira,
SPECIES AND SSP - nigrican,
SCIENTIFIC NAME - Makaira nigrican
AUTHORITY - Lacepede
TAXONOMY REFERENCES - 111, 182 and 183
Taxonomy - 1 (DRAFT) - Status
Species marlin, blue
Species Id M010409
Date 26 AUG 96
STATUS
Coded Status
Sport Fish
Game (Consumptive Recreational)
Commercial
Existing, FMP exists
Commercial/consumption
REFERENCES FOR STATUS - 182 and 111
COMMENTS ON STATUS -
The Blue Marlin is one of the largest game fishes caught in the Atlantic
Ocean.*182*
A Billfish Fishery Management Plan was prepared jointly by the South
Atlantic, New England, Mid-Atlantic, Gulf of Mexico, and Caribbean Fishery
Management Councils. It establishes a management regime for billfishes
harvested from the management unit and possessed shoreward of the outer
boundary of the EEZ (Exclusive Economic Zone) of the Atlantic Ocean,
Gulf of Mexico and Caribbean Sea.*111*
Status - 1 (DRAFT) - Distribution
Species marlin, blue
Species Id M010409
Date 26 AUG 96
DISTRIBUTION
Distribution - 1 HABITAT ASSOCIATIONS
NATIONAL WETLAND INVENTORY CODES
NWI NWICLS NWIMOD NWISPEC
Marine OW0 H
REFERENCES FOR NWI - 111
COMMENTS ON HABITAT ASSOCIATIONS -
The habitat for the billfishes in the management unit is the oceanic
pelagic waters of the Atlantic Ocean. Blue and white marlin, sailfish and
spearfish venture into coastal waters only occasionally, usually in areas
such as the Caribbean Islands where there is little continental shelf or in
southeast Florida, where the shelf is very narrow and the Gulf Stream is in
close proximity to shore. Because of their oceanic nature, the specific
habitat interactions of these species are not well known.
Blue marlin are more oceanic than white marlin. These fish, like most
large pelagic predators are associated with oceanic features that
concentrate food, although they also appear to concentrate seasonally for
spawning. Naturally, recreational fisheries tend to concentrate in those
areas.
The habitat of the billfishes is the water column itself. Because of their
oceanic nature, changes to the habitat of sufficient magnitude to directly
impact the billfish fishery are relatively unlikely. However, oil spils,
ocean dumping, OTEC projects (Offshore Thermal Energy Conversion), and the
general degradation of the oceanic environment may impact the survival of
larvae and possibly adults (either directly or through the food
chain).*111*
Water temperature appears to be a major factor influencing the distribution
of billfishes. They are generally found in waters with surface
temperatures above 70 degrees F (21 degrees C).
Major currents also play an important role in the distribution and
migration of billfishes. Concentrations of sailfish, white marlin and blue
marlin are found within or near the Gulf Stream, which flows in a
northeasterly direction along the Atlantic coast of the U.S. at varying
distances from shore. In the northeastern Gulf of Mexico, billfishes are
abundant in and around the Loop Current. The northward extent of their
migration into the Gulf appears to be related to the northward extent of
the current's penetrations.
Localized occurrence of blue and white marlin is influenced by bottom
topography. Steep drop-offs, submarine canyons, and shoals, when located
in areas with suitable water conditions, often harbor feeding
concentrations of these species. Along the Atlantic coast of the United
States, important topographical features of this nature include the Five
Fathom Bank off southern New Jersey; the Cigar southeast of the Virginia
Capes; the Jack Spot off Maryland; Hudson Canyon, southeast of New York
City; Wilmington, Baltimore and Washington Canyons off the Delmarva
Peninsula; and Norfolk Canyon off the Virginia Capes. DeSoto Canyon in the
northeastern Gulf of Mexico and drop-offs in the Bahamas, Puerto Rico and
the Virgin Islands also attract feeding concentrations of marlins.*189*
Habitat Associations - 1 (DRAFT) - Food Habits
Species marlin, blue
Species Id M010409
Date 27 AUG 96
FOOD HABITS
TROPHIC LEVEL -
CARNIVORE
REFERENCES FOR TROPHIC LEVEL - 189
LIFESTAGE FOOD FOOD PART
General Osteichthyes Not Specified
General Squid, Octopus Not Specified
REFERENCES FOR GENERAL FOOD - 189
COMMENTS ON FOOD -
The blue marlin is primarily a daytime feeder. It feeds at or near the
surface, in inshore areas as well as out in the open sea. Tuna-like fishes
were found to be the chief components of the blue marlin diet off Puerto
Rico. Frigate mackerel, Auxis thazard, was the most frequently occurring
individual item, found in 20 percent of the specimens containing
identifiable remains. Blackfin and skipjack tunas (Thunnus atlanticus and
Euthynnus pelamis) were also important, occurring in approximately 23
percent of the specimens. In studies conducted in the Gulf of Mexico, the
importance of individual food items in the diet of blue marlin varied from
year to year. Dolphins were the most consistently important food. The
blue runner (Caranx crysos) and the Atlantic bonito (Sarda sarda) were also
major components of the diet in this area.*189*
Food Habits - 1 (DRAFT) - Environment Associations
Species marlin, blue
Species Id M010409
Date 27 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
G Water Temperature: Greater than 27 degrees C
G Water Temperature: Between 21-27 degrees C
E Water Temperature: Greater than 27 degrees C
E Water Temperature: Between 21-27 degrees C
E
E
REFERENCES FOR ENVIRONMENTAL ASSOC_ - 189
REFERENCES FOR EGG ENVIRONMENTAL ASSOC_ - 189
COMMENTS ON ENVIRONMENTAL ASSOCIATIONS -
The National Marine Fisheries Service has recorded blue marlin in waters
with temperatures ranging from 70 degrees F (22 degrees C) in February to
87 degrees F (31 degrees C) in July. The optimal water temperature has
been suggested to be approximately 79 degrees F (26 degrees C).*189*
COMMENTS ON EGG ENVIRONMENTAL ASSOC_ -
Blue marlin spawn in the Northwest Atlantic between April and September in
waters with temperatures between 79 and 84 degrees F (26 to 29 degrees C)
and salinities between 35 o/oo and 36 o/oo.*189*
Environment Associations - 1 (DRAFT) - Life History
Species marlin, blue
Species Id M010409
Date 27 AUG 96
LIFE HISTORY
Population Attributes:
The existence of two separate stocks concentrated on the western side of the
North and South Atlantic Oceans has been suggested. Available data on the
occurrence of blue marlin larvae also support the hypothesis of separate
North and South Atlantic spawning populations.*189*
Migration Patterns:
Little is known of the migratory patterns of the two groups of blue marlin
within their respective hemispheres. Data obtained from blue marlin tagging
has been limited by the small number of releases and the low rate of return
of tagged fish. One return, however, indicates that blue marlin
occasionally make trans-Atlantic migrations. A year round concentration of
blue marlin occurs throughout the Caribbean. Some of these fish move
northward in summer to provide good fishing from the east coast of Florida
to Long Island, New York. In 1986, a 1,175 pound blue marlin was caught
off Montauk, New York.*189*
In the northern Gulf of Mexico, the Loop Current, an extension of the
Caribbean Current which flows northward through the Yucatan Channel and into
the Gulf, seems to influence blue marlin occurrence and distribution. The
northward extent of the current may determine the northward extent of both
blue and white marlin in the Gulf. Also, the current appears to "hold the
fish together" when it is strong, and when it is weak, marlin are apparently
widely scattered over the Gulf. Blue marlin prefer blue water.*189*
Spawning:
Blue marlin in the western North Atlantic spawn in the warm months of the
year. It has been suggested that spawning occurs far offshore, with young
developing near the surface. Blue marlin spawn in the Northwest Atlantic
between April and September in waters with temperatures betwen 79 and 84
degrees F (26 and 29 degrees C) and salinities between 35 o/oo and 36 o/oo.
A spawning population has been found off Puerto Rico from May to November.
May and June have been suggested to be the peak spawning months off the
Bahamas.*189*
Age and Growth Characteristics:
There is little validated information regarding the age composition of the
blue marlin population, age-weight relationships, growth rates, or size and
age at first maturity.*189*
No estimates of natural mortality rates or longevity of blue marlin are
available. These estimates are often made from tag return data and tag
return rates for blue marlin are extremely low (1% in recent years).
However, 30 percent of tagged fish recoveries occurred after more than 2
years at liberty suggesting that the species has a long life span. The
longest period of release was eight years. The largest blue marlin taken in
the Atlantic Ocean weighed 1,282 pounds (582 kg). It seems unlikely that
such a size could be attained in a short life span, even assuming a rapid
growth rate.*189*
Abundance and Present Condition:
The blue marlin stock may be beginning a recovery from excessive catches and
effort of the 1960's and mid-1970's.
Life History - 1 (DRAFT) - Life History
Species marlin, blue
Species Id M010409
Date 27 AUG 96
Total fishing effort for blue marlin declined substantially after 1977.
With the decline in effort, some increases in total catch may have occurred
in waters adjacent to the U.S. Catch per unit effort and total catch by
recreational fishermen in the Gulf of Mexico have increased since 1977.
Although most of the increase is attributed to a reduction in Japanese catch
in the Gulf, some could also be the result of a general increase in
abundance. Press reports from the Caribbean and the Bahama Islands also
report a recent increase in blue marlin catch.*189*
Predation:
Predation by dolphins on billfish in larval and juvenile stages is
significant. Shark attacks on billfishes hooked on longline gear have been
observed frequently, but the degree of predation by sharks on free swimming
billfishes is unknown.*189*
Competition:
Studies have indicated that the centers of billfish abundance coincide
during certain seasons of the year. Since the dietary preferences of the
three species (white and blue marlin and sailfish) are similar (fish and
squid are important food items for all three), it is likely that some
competition for food and space occurs. An inverse relationship between the
relative abundance of white and blue marlin during the sport fishing season
in the Gulf of Mexico has been observed. It is possible that a competitive
relationship of some sort exists between the two species. However, these
differences in relative abundance could also be due to changes in fishing
method or location of effort directed to one or the other species, i.e.,
what types of bait or whether "light" or "heavy" tackle is being used.*189*
Population Trends:
Considering the number of countries currently participating in the billfish
fishery outside of national jurisdictions, the probable future condition of
the stocks cannot be accurately assessed without knowing the long range
intentions of these fisheries with regard to their high seas operations and
coastal fisheries. However, in view of the increasing world demand for
protein, accompanied by increasing prices for tuna and billfish in world
markets, sustained or increasing fishing effort for billfishes can
reasonably be expected.
The average size of both blue and white marlin has increased in recent
catches. Increase in size would be consistent with (1) a general decline in
the number of young fish entering the fishery, (2) the progression of a
large year-class (or year-classes) through the fishery, or (3) shifts of
the fishery to times or places where older marlins are disproportionately
abundant. Which of these is the cause of increasing size of fish in the
catch is not apparent from available information. However, fishing effort
has shifted spatially and temporally in recent years.*189*
REFERENCES FOR LIFE HISTORY- 189
Life History - 2 (DRAFT) - Management Practices
Species marlin, blue
Species Id M010409
Date 27 AUG 96
MANAGEMENT PRACTICES
RESULT MANAGEMENT PRACTICE
Existing Regulating harvest of species being described
Existing Prohibiting harvest of species being described
Existing Regulating harvest - setting size limits
Existing Regulating commercial harvest levels
Existing Other management practices [specified in comments]
Beneficial Controlling pollution [thermal, chemical, physical]
REFERENCES FOR BENEFICIAL MANAGEMENT PRACTICES - 111
REFERENCES FOR EXISTING MANAGEMENT PRACTICES - 111
COMMENTS ON MANAGEMENT PRACTICES -
Economic, Social and Ecological Considerations of Management:
The higher the availability of billfishes within the EEZ (Exclusive Economic
Zone), the greater the likelihood that U.S. anglers will catch a billfish.
Any increase in the likelihood of success should have a substantial,
positive impact on the socio-economic values of the fishery. Thus, the
optimum yield will result from reserving to the U.S. recreational fishery
the most billfish possible occurring in the EEZ at any given time. The
recreational billfish fishery plays a significant role in the economic and
social well being of a great many people.*111*
Fishery Management Plan:
A Billfish Fishery Management Plan was prepared jointly by the South
Atlantic, New England, Mid-Atlantic, Gulf of Mexico, and Caribbean Fishery
Management Councils. It establishes a management regime for billfishes
harvested from the management unit and possessed shoreward of the outer
boundary of the EEZ (Exclusive Economic Zone) of the Atlantic Ocean,
Gulf of Mexico and Caribbean Sea.*111*
Summary of FMP (May, 1988):
Management Measure #l: No Sale Provision
The no sale provision is for the express purpose of preventing a commercial
market for these species from developing, thus preventing the primary
objective of the FMP from being realized.
Management Measure #2: Minimum Sizes
The intent of this management measure is to significantly reduce billfish
mortality in the recreational fishery by releasing more billfish alive,
which will increase the availability to the recreational fishery, thus
helping accomplish the plan's principal objective.
Management Measure #3: No Possession By Longliners & Drift Net Vessels:
This measure is intended to maximize the release of live billfish by those
commercial vessels that would routinely catch them in the course of their
commercial fishing operation. Since the objective of this plan is to
maximize the availability of billfishes to the recreational fishery, any
measure which results in the release of live billfish will help accomplish
Management Practices - 1 (DRAFT) - Management Practices
Species marlin, blue
Species Id M010409
Date 27 AUG 96
that objective.
Management Measure #4: Data Reporting Requirements
Data reporting requirements consist of a recommendation for the continuation
of the existing logbook requirement and voluntary observer program as
specified in the swordfish FMP and mandatory reporting of catch and effort
data for recreational fishing tournaments.
Management Measure #5: Puerto Rican Handline Exemption:
A traditional, artisanal handline fishery in Puerto Rico has a small bycatch
of billfishes, primarily blue marlin. The capture of a billfish in this
small-scale fishery is a rare, but fortuitous event for the few artisanal
fishermen in Puerto Rico. This measure provides the only exemption to the
no sale provision, complicating enforcement, and providing a potential
loophole through which illegally harvested billfish may enter commercial
markets. To lessen these impacts restrictions have been placed on this
exemption.*111*
Foreign Longline Fishery:
Longline catch rates for white marlin, blue marlin and sailfish/spearfish
within 200 miles of the U.S. have declined markedly in recent years. In
recent years, Japanese fishing effort has been reduced dramatically in the
EEZ. In 1986, for example, 272 white marlin and 37 blue marlin were
recorded by U.S. observers (100 percent coverage). Of those, 54 percent of
the white marlin and 57 percent of the blue marlin were dead. The Japanese
have agreed not to fish in the Gulf of Mexico and have not done so since
1982.*189*
Need for International Management Plan:
There is a pressing need for the rapid development and institution of an
international management plan in order to maintain the stocks of billfish in
an expanding fishery. Other unregulated common property fisheries have
overfished the population to varying degrees ranging from reducing annual
yields below MSY (maximum sustainable yield - the largest quantity of fish
that can be harvested annually from a resource without reducing its
long-term productive potential), through economic disruption of the fishery
to its economic extinction. In the absence of an international fishing
regime, further increases in the level of effort for billfishes are likely.
Considering the status of these stocks (billfishes), such increases in
effort are not likely to produce increases in yield, at least for blue and
white marlin, and could result in recruitment overfishing and depletion of
the stocks.*189*
Habitat areas of Particular Concern:
There are no habitat areas of particular concern in the sense that the term
is generally applied (e.g., estuarine nurseries in the case of estuarine
dependent species). The billfishes are highly migratory, oceanic species
whose habitat and environmental requirements during early stages of their
life cycles are not well known. Billfish spawning grounds are at or near
the surface of oceanic waters relatively far from coastal sources of
pollution. Offshore pollutants, such as oil spills, may be deleterious to
the young stages. Billfish can also be influenced by subsurface and
substrate pollutants, such as heavy metals, pesticides and radionuclides,
Management Practices - 2 (DRAFT) - Management Practices
Species marlin, blue
Species Id M010409
Date 27 AUG 96
through the food chain. Billfish living on or near canyons of the
continental shelf may be affected by pollutants carried through direct ocean
dumping.
Oil spills, ocean dumping, OTEC projects (Offshore Thermal Energy
Conversion), and the general degradation of the oceanic environment may
impact the survival of larvae and possibly adults. The effects of
sub-lethal concentrations of chemical and other pollutant on these species
is not known, but their oceanic distribution suggests a requirement for
extremely high water quality. Any degradation of this water quality can be
expected to impact their survival which would obviously impact the fishery.
Habitat Preservation, Protection and Restoration Recommendations:
1) Research should be conducted to quantify the impacts of ocean disposal
of dredge materials, industrial waste and sewage sludge on oceanic pelagics
such as billfish.
2) The disposal of contaminated sewage sludge, industrial waste and
contaminated dredge material that would degrade the environmental quality of
the marine environment utilized by billfish should be prohibited.*111*
Description of Vessels and Gear Employed:
Sport fishing for marlins is done with rod and reel. The boats used in the
U.S. sport fishery for billfishes range from 16 to more than 65 feet in
length and the method of power ranges from outboard engines to large
diesels. Marlin fishing generally requires a large (greater than 25 feet in
length), inboard, usually diesel-powered vessel because of the distance that
has to be traveled to reach suitable fishing grounds, as many as 75 to 100
miles from shore off many areas on the Atlantic and Gulf coasts. The use of
smaller outboard powered boats (in the 16 to 25 foot range) in the fishery
is particularly evident off the southeast coast of Florida from Key West to
Ft. Pierce and in the northern Gulf of Mexico and the Caribbean where
productive billfish fishing waters are only a few miles from shore. The
development of small, fast, sea worthy fishing boats (20-30 feet in length)
and reliable high-powered outboard engines has made even the offshore
fishing grounds accessible to a great many anglers.*111*
Fishing Seasons and Areas:
The U.S. recreational fishery for billfishes is conducted from every state
along the Atlantic and Gulf coasts from Massachusetts southward, as well as
from Puerto Rico and the Virgin Islands. Anglers from the U.S. also fish
extensively in foreign waters, particularly offshore of the Bahamas,
Venezuela, Mexico, Dominican Republic and British Virgin Islands.
The fishery is, for the most part, a seasonal one, which coincides with the
months of highest availability of billfishes within the EEZ. Off the
Atlantic and Gulf coasts of the U.S., recreational activity is most intense
from April through October. In the Caribbean EEZ, fishing for billfish is a
year-round activity with seasonal peaks for each species.*111*
Management Practices - 3 (DRAFT) - References
Species marlin, blue
Species Id M010409
Date 27 AUG 96
References
111* South Atlantic Fishery Management Council. 1988. Fishery
Management Plan, Final Environmental Impact Statement,
Regulatory Impact Review, and Initial Regulatory Flexibility
Analysis for the Atlantic Billfishes. South Atlantic Fishery
Management Council Charleston, SC pp 26.
182 * Manooch, Charles S. III. 1984. Fisherman's Guide to the
Fishes of the Southeastern United States. North Carolina State
Museum of Natural History Raleigh, North Carolina:362.
183 * Gusey, William F. 1981. The Fish and Wildlife Resources of
the South Atlantic Coast. (ed.). Environmental Affairs, Shell
Oil Company Houston, Texas:552.
References - 1