Blue Marlin - White Marlin Severity of Atlantic Declines, Their Causes and What Needs to be Done. Here are the Facts.

Blue Marlin Population Abundance

Fishing Pressure on Blue Marlin

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4 times the Sustainable              Level (1.0)

White marlin are found only in the Atlantic Ocean, while blue marlin (like swordfish) inhabit not only the Atlantic but also the Pacific and Indian Oceans. For stock assessment purposes, both Atlantic blue marlin and white marlin have recently been treated by the scientists advising ICCAT as single interbreeding stocks throughout their entire Atlantic Ocean range.  In the past, ICCAT's scientists also assessed both the North and South Atlantic sub-populations separately, and they continue to do this for swordfish. However, for the reasons specified below and in our pages devoted to their "hot spots" - see links below - we are convinced that there are separate, non-interbreeding sub-populations of both Atlantic marlin species above and below the Equator. This is an important distinction since recovery of the North Atlantic sub-populations of white and blue marlin (and swordfish) is in no way dependent on obtaining reductions of commercial fishing pressure in the South Atlantic. Both Atlantic marlin species are caught and retained by all industrial fishing fleets, except those of the United States (whose commercial vessels are required to release all billfish) where billfish are reserved exclusively for the recreational fishery.  However, about 25% of blue marlin and 30% of white marlin caught on longlines are already dead on arrival at the vessel.  As depicted in the ICCAT figure to the upper left, the abundance or biomass (total weight of fish) of the Atlantic-wide population of blue marlin has declined to just 20% of its pre-longlining (1960) level. In 40 years it has thus declined from a healthy level (of two times the level associated with producing the maximum sustainable yield, MSY) to only 40% of its MSY level.  The zero line means extinction.  Responsible fishery managers would never allow the biomass to drop and remain below the MSY level (depicted as the dashed line at 1.0). ICCAT claims its objective is to manage fishing by its members so that all stocks produce the maximum sustainable catch (or MSY). As shown in the ICCAT figure to the upper right, the cause of this decline in abundance is excessive fishing pressure by commercial fishing fleets.  By 2000, it had grown to 4 times higher than the sustainable level or MSY (indicated by the dashed line at 1.0).  Fishery managers should never allow fishing mortality to remain above the MSY level.

White Marlin Population Abundance

Fishing Pressure on White Marlin

< 8 times the Sustainable           Level (depicted as the dotted line at1.0)

For white marlin, as depicted in the two ICCAT figures above, the situation is even more grim.  By the beginning of 2000, the biomass (left) had been driven down to just 13% of the sustainable level (MSY) and it is declining rapidly.  A year later it was estimated to have reached 12% of its MSY. This means this Atlantic population has declined to just 6% of its pre-longlining abundance and it is declining by 3% each year! The cause, excessive fishing pressure (right) had been allowed to climb consistently from the sustainable (MSY) level in 1980 to nearly 8 times higher than the MSY level by 2000.  At this rate of decline, Atlantic white marlin will become functionally extinct (unable to sustain a viable breeding population) in less than 5 years and blue marlin in perhaps 10 years! Fishery biologists know that the abundance of a population under proper management should never drop below the MSY level and should remain well above it, if it is to also provide sufficient numbers and larger fish to support a quality recreational fishery and to provide enough large fish to maintain essential predator-prey balance (as required by the Sustainable Fisheries Act's new "optimum yield" definition).  The kill caused by fishing - called fishing mortality - has increased dramatically.  For white marlin it has reached 8 times the sustainable level and it appears to be accelerating higher.  For blue marlin, fishing pressure has reached 4 times the long-term sustainable level.  Fishing pressure should never be allowed to exceed the MSY level (1.0) for a population that has been seriously depleted, such as these.  Maps showing the locations where U.S. longline vessels catch the greatest numbers of North Atlantic marlin (sailfish and swordfish) can be seen by clicking the links (in red) entitled "Hot Spots" located near the bottom of this page.  These maps depict primary spawning and feeding areas by quarter for both 1994 and 1995. Consequently, both blue marlin and white marlin stocks are continuing to decline rapidly.  They are also rapidly approaching extinction (the zero line).  Their populations are both well below the level at which there is a danger of recruitment failure (considered for these species to be at 50% of MSY).  Passing such a threshold means there are too few adult breeders to replace the population, which can then spiral ever faster towards extinction.  Since the commercial vessels are targeting other species whose populations are stronger, the kill of marlin will continue until it becomes unprofitable to target swordfish and the larger tunas.  Yellowfin tuna, for example, are estimated to still be at the MSY abundance level, and thus they can withstand a great deal more commercial fishing pressure.  Since 30% of all white marlin and 25% of the blue marlin caught on longlines arrive at the vessel dead, this kill will continue as long as commercial vessels fish in these species' primary spawning areas and feeding grounds (their "hot spots"). The two Atlantic marlin species will not be able to survive the continued pressure targeting swordfish and tunas.  They are already too close to the brink of extinction. This information has been provided on an annual basis to those responsible for managing and conserving these fishery resources - ICCAT and NMFS.  Commercial vessels (longlines, gillnets and purse seines) are responsible for 99% of the reported kill of Atlantic blue and white marlin.  Recreational fishermen, who voluntarily release a self-reported 99% of their catch to help conserve the resource, are responsible for less than 1% of the annual fishing mortality. Recently, ICCAT finally recognized the problem and adopted a requirement that member nations limit their landings of blue marlin and white marlin to 50% and 67%, respectively, of their 1999 landings. This provision was to begin June 1, 2001. If all member nations were to comply fully, the overall fishing mortality rate for Atlantic white marlin can be reduced from 8 times the sustainable rate (as shown in the graph above) to, at best, 2.6 times higher than the sustainable rate (8 x 0.33). This is still much too high. While better late than never, ICCAT's new requirement will at best only slow but not stop or reverse the white marlin's rapid decline toward extinction. For Atlantic blue marlin, the new requirement will do the same thing (reduce the fishing mortality rate from 4 times too high to 2 times too high). Thus, it will slow but not reverse the steady decline toward extinction. And since 30% of all white marlin and 25% of all blue marlin caught on longlines arrive at the vessel dead (regardless of whether they were to be retained or discarded), this additional kill will continue as long as these commercial vessels are allowed to fish (even for other target species) in the marlin's primary spawning areas or feeding grounds. WHAT ADDITIONAL ACTION IS NEEDED? -- CLOSE THE "HOT SPOTS" TO LONGLINES We refer to the white marlin's (and blue marlin's) critical habitats - their primary spawning sites and feeding grounds - as their "hot spots." These small, distinct areas are used year-after-year. They have been mapped based on 10 years of U.S. longline catch records reported to NMFS. To see the locations of their prime spawning sites and feeding areas, click on the links below entitled "Hot Spots" of White and Blue Marlin.  To see the specific areas under U.S. jurisdiction that we have recommended for closure to longlines, click here. These "hot spots" are not just the areas where the longliners fish most heavily. As can be seen in the following plots showing the yearly extent of U.S. longline vessels' sets (1992, 1995, 1996 and 1997), longliners are covering a much greater area of the North Atlantic than just the area of these "hot spots." In fact, we estimate that closing all the white marlin's "hot spots" in the North Atlantic would deny U.S. longliners access to only about 2% of the area they normally fish. But, it would eliminate about 85% of their interactions with white marlin. Obtaining these closures and reducing the kill of white marlin accordingly is the primary objective of our ESA Petition. It requests that the U.S. government first "list" the white marlin as either "threatened" or as "endangered" and then protect it and its critical habitats (its "hot spots") under authority of the Endangered Species Act (see link to the White Marlin ESA Petition below). Obtaining closures in the North Atlantic "hot spots" is important because, based on all the information available, we are convinced that there is not one Atlantic-wide population of white marlin or blue marlin, but two - one in each hemisphere. The South Atlantic sub-populations of both marlins appear to spawn primarily off the northeast coast of Brazil (Royal Charlotte Bank area) during late spring-early summer in the southern hemisphere (probably peaking in November-early December). The North Atlantic sub-populations ("our" white and blue marlin) spawn in the Caribbean region during late spring-early summer (peaking from gonad examinations in May-early June). From the 10 years of longline catch records by quarter we know that it is most probably concentrated in the large gaps between the larger islands of the Caribbean (such as the Mona Passage between the Dominican Republic and Puerto Rico where large concentrations of larval white marlin have recently been found). Thus, spawning by the North and South Atlantic sub-populations of both white marlin and blue marlin occurs 6 months apart and the two centers of spawning activity are separated by 4,000 miles of ocean. Clearly (for both the white marlin and the blue marlin), these are not single Atlantic-wide populations, but two entirely distinct sub-populations which do not interbreed. The same is already accepted by the international scientific community for North and South Atlantic swordfish - 2 separate and distinct sub-populations, one in each hemisphere. Therefore, overfishing on one sub-population of any of these three species (swordfish, blue marlin or white marlin) will have absolutely no effect on the other sub-population. We may not be able to save white marlin or blue marlin of the South Atlantic because that is totally dependent on international agreements at ICCAT. But, the U.S. can unilaterally protect the North Atlantic sub-populations (of both marlins) to a great extent by prohibiting longlining in their "hot spots" that are located in U.S. waters. This is true simply because, except for spawning, most of the sub-population's members apparently spend a large part of their adult life in U.S. waters. This is particularly true of white marlin and less so for blue marlin and swordfish which range farther out into the mid-Atlantic (the site of the movie "The Perfect Storm") during summer through fall following (the edges of) the Gulf Stream. All three species, however, appear to use the same very small and distinct areas in the Caribbean region as their primary spawning sites. The most important "hot spots" are used at the same time of year and for the same purposes (both spawning and feeding) by not only the North Atlantic white marlin sub-population, but also the North Atlantic sub-populations of swordfish and blue marlin. So, closing them to longlines to protect white marlin will also markedly benefit blue marlin and swordfish as well. Be sure to see the other sections of this website for details on the population declines of each of the Atlantic Ocean's big fish. GET INVOLVED YOURSELF If you want to help us prevent North Atlantic white marlin from sliding into extinction (as well as help protect declining populations of Atlantic blue marlin, swordfish, bluefin tuna, bigeye tuna, mako sharks, spearfish, sailfish and many other large pelagic species), become a Sponsor.  To do so go to BigMarineFish.com/sponsor.html

THE PACIFIC SITUATION The population status of Pacific marlin (black marlin, blue marlin and striped marlin), sailfish and the rare spearfish are not well documented.  But, commercial fishing effort is already high and escalating.  The situation in the Atlantic provides a stark example of what is probably also occurring in the Pacific.  It's just not being as well documented.

"Blue and Allisons" by Don Ray

Don Ray Studios

"Playin' the Blues" by Don Ray

Don Ray Studios

MORE PAGES: Primary Spawning and Feeding Area Maps Blue Marlin White Marlin Sailfish Bluefin Tuna Swordfish Congress' Longline Closures Bills Will They Work? Severity of Atlantic Population Declines The Facts - Headed for Extinction Bluefin Tuna Swordfish Sailfish Sharks Daily "Kill-o-Meter" Endangered Species Act White Marlin ESA Listing Petition White Marlin "Hot Spots" Blue Marlin "Hot Spots" Recommended Longline Closure Areas Articles on Big Game Fish and Fishing Overview and List Photos of Big Game Fish Largest Marlin, Bluefin, Many World Records   Jim Chambers Chambers and Associates Description Become a Sponsor List of All Pages on this Website Home

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Daily "Kill-o-Meter"

Longliners fish most heavily during the periods when the moon is brightest. So, this real-time image of the moon phase shows when the kill of swordfish is greatest and least. It also shows when the kill of blue marlin, white marlin, sailfish, sharks, tunas, sea turtles, marine mammals and a host of other marine life is also greatest - even though they are not even targeted. For more, see link above.

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