GOING, GOING, GONE!

A National Feature Article in the Jan/Feb 2001 Issue of The Big Game Fishing Journal By Jim Chambers

The most magnificent game fish of the Atlantic Ocean - bluefin tuna, blue marlin, white marlin, swordfish, sailfish, bigeye tuna and many large sharks - are getting close to disappearing forever.

Anyone familiar with offshore fishing along the U.S. Atlantic Coast and in the Gulf of Mexico and Caribbean knows the top big game species are much less abundant than they used to be. Decades of overfishing by the industrial fleets of many countries has been allowed by the international body responsible for management of the most valuable species, particularly tuna and swordfish. They use longlines, gillnets and purse seines which are highly efficient at catching the target species, but also catch and kill large numbers of less-marketable species, including other billfish and sharks. As a result, populations of Atlantic blue and white marlin, western Atlantic sailfish, north Atlantic swordfish, western Atlantic bluefin tuna, and Atlantic bigeye tuna have all been driven to dangerously low levels with some still continuing their steep decline. In the greatest danger are white marlin, bluefin tuna and blue marlin. Overfishing is pushing all these species toward the edge of that slippery slope from which they may be unable to recover - even if all fishing were to stop. And unless substantial conservation measures are taken immediately, some could be pushed into extinction within only a few years.

International fishing pressure on all of them is well above that which would produce the maximum sustainable catch - the goal of responsible fishery managers. Average sizes for swordfish, for example, have declined from large, mature fish weighing several hundred pounds to just babies, since most don't have a chance to grow large or old enough to spawn even once.

How Severe is the Problem?

By looking at the big picture and considering the scientific evidence developed during the last 40 years, a disturbing picture emerges. Decimation of the Atlantic Ocean's premiere game fish in just the last three decades has been astounding! Although it is not as well monitored and documented, the same may also be occurring on a massive scale throughout the Pacific and the rest of the world's oceans.

Purpose of this Article

The purpose of this article is to help the big game fishing community understand the severity of the worldwide problem, using the Atlantic fishery as an example. It summarizes the scientific community's understanding of the population status of what are considered the most important big game species of the Atlantic Ocean - bluefin tuna, swordfish, blue marlin, white marlin, sailfish, bigeye tuna and sharks - and describes actions we should take to preserve them. It's based on stock assessments conducted by the International Commission for the Conservation of Atlantic Tunas (ICCAT), which since its formation in 1969, has claimed management authority over all fishing for tunas and tuna-like fishes in the Atlantic Ocean. ICCAT is composed of 27 member nations. Its stated management objective is to produce the maximum catch on a sustainable basis, or as fishery scientists refer to it, the "maximum sustainable yield" (MSY).

Are our "Hot Spots" their Last Refuges?

Today's prime big game fishing destinations worldwide include a relatively few, distant locations such as the Azores, Madeira, Ghana, Brazil, Venezuela, Panama, Costa Rica, the Great Barrier Reef, Hawaii and Mauritius. For example, this year's IGFA Barta Blue Marlin Classic was held at the Mona Passage, a very deep channel between Hispanola and Puerto Rico. Like other major passes between the Caribbean Islands, this appears to be one of a relatively few major spawning sites for blue marlin, white marlin, sailfish and, especially, swordfish (the primary species targeted by longliners).

As any population declines in abundance, its distribution collapses around those areas most critical to its survival - spawning grounds and important feeding areas. Thus our "hot spots" may actually be the last refuges for these species. Certainly, the areas most heavily fished by the commercial fleets are their key spawning and feeding grounds (for maps showing these areas in the Atlantic, see our website at www.Chambers-Associates.org).

The "Point of No Return" and the "Death Spiral"

As any fish's population declines further, it will eventually reach a critical point at which there are no longer enough adults remaining to find each other during their annual spawning period. From this point onward, fewer and fewer young will be produced each successive year and the population will spiral downward until it disappears completely. After it passes that critical point, the species is simply unable to save itself. Fewer and fewer individuals remain each year until the "death spiral" begins and eventually there are none left.

This critical "point of no return" for each species depends on its life history, reproductive strategy, and behavior. Those which produce huge numbers of eggs and release them away from concentrations of tiny predators will have a distinct advantage. Swordfish, for example, spawn much deeper than other billfish. The females of species like blue and black marlin become massive, allowing them to produce many times more eggs than smaller individuals of the same species. (This is the main reason we should do everything we can to protect rather than kill the largest individuals as trophies or for tournament points.) The solitary hunting swordfish has a more difficult time finding its mates during the spawning season than do bluefin tuna, which likely travel in the same school throughout their entire lives. However, as fishing pressure removes individuals and school size declines, even bluefin may reach a point at which there are too few adults to provide what we think is the minimum number needed to sufficiently "excite" the group for successful spawning to occur. They may be old enough, but fail to spawn because they just don't "get in the mood." As more and more schools decline in size, to the point where they also don't spawn, fewer and fewer young are produced each year. Eventually, the point of no return is reached and the slide to extinction is begun from which the population is unable to recover. For each of these premiere game fish, the question is, "How close are their populations to their critical point and where are they headed?"

Swordfish

Swordfish are the primary target of the international fleets. The average size landed commercially has declined from 300 to 400 pounds at the turn of the 20th century and over 266 pounds as recently as 1961 (when longlines replaced harpoons as the primary commercial gear used), to only 88 pounds today. Most (almost two of every three) are now caught before they have a chance to spawn even once. Of the females, 83 percent caught are still immature. ICCAT's minimum size limit is now 44 pounds (equal to 33 pounds headed and gutted, or "dressed weight"). This size limit has nothing to do with the size at which a swordfish becomes mature. On average, females do not mature until they reach age 5 and about 150 pounds (live weight), while males mature at 3 years and 72 pounds. U.S. longliners, particularly those fishing in the primary nursery areas around Florida, routinely "discard" 40 to 50 percent of the swordfish they catch because they are too small to sell legally. Due to the trauma involved in longline retrieval (e.g., jaws and gills torn apart) virtually all of these fish (age 1 or 2) are either dead already or die soon thereafter. In 1998, the U.S. fleet discarded 485 metric tons of baby swordfish, down from 708 in 1994. However, this represented nearly half of the total swordfish they landed. The Spanish fleet's record is worse. At least 75 percent of its total swordfish landings are composed of fish weighing less than the minimum size!

For stock assessment purposes, the north Atlantic swordfish population is considered one interbreeding unit throughout the North Atlantic Ocean, which includes the Mediterranean Sea, the Gulf of Mexico and the Caribbean Sea. As depicted in the figure top left, this stock has declined from a healthy level of nearly two times the MSY level (indicated by the horizontal line at 1.0) before 1960, to a fraction of MSY by the end of 1998.

To put this in context, responsible fishery managers try to prevent the biomass from dropping below the MSY level by keeping fishing mortality (i.e. fishing pressure as depicted in the lower figure at left) from climbing above the MSY level. Overfishing occurs when the population's biomass declines below the MSY level (upper figure), and "recruitment failure" begins as the biomass falls below 50 percent of MSY. (Recruitment failure means there are no longer enough adult spawners to replace the population.) Extinction becomes inevitable as the population approaches zero.

By the end of 1998, the north Atlantic swordfish population had declined to 65 percent of that needed to produce the MSY and fishing pressure was 34 percent higher than the rate the stock can sustain (MSY). The last stock assessment indicated the biomass had increased slightly - from 58 to 65 percent of MSY. However, this small increase may be an illusion, since it does not include the landings of non-ICCAT members (which are considerable) and assumes honest reporting by all ICCAT members.

Bottom line: the northern Atlantic swordfish stock has been declining steadily at the same rate each year for the past 20 years. ICCAT's scientific advisory committee has meticulously documented destruction of this population each year, yet ICCAT has failed to limit the catch of its member states sufficiently in order to reverse the decline.

However, the good news is swordfish are capable of a very rapid recovery if given the chance. Large females can produce 30 million eggs. Model results based on the stock at the end of 1995 and again in 1998 indicate that if all fishing were to cease, the stock could recover to the MSY population level in only three years. A 10-year recovery (with a 50:50 chance of success) would require an 18 percent catch reduction from current (1998) levels. However, ICCAT has recommended quota cuts that are insufficient to cause a recovery - even if all fishing by non-ICCAT members were to cease.

Marlin

Blue marlin and white marlin are each considered a single interbreeding stock throughout their entire Atlantic Ocean range. They are caught and retained by all industrial fishing fleets, except those of the United States, whose commercial vessels are required to release all billfish as they are reserved exclusively for the recreational fishery.

Atlantic-wide populations of both blue and white marlin have declined in abundance from healthy levels of two times the level associated with producing the MSY (the horizontal dotted ine at 1.0 on the figures at left), which existed prior to 1960, to dangerously low levels today. For their population trends reproduced from ICCAT's most recent stock assessments conducted in the summer of 2000, see the white and blue marlin figures at left; the results are alarming.  The biomass of blue marlin (top figure) has now declined to only 40 percent of the MSY level, which is well below the level at which recruitment failure begins - 50 percent of MSY. The cause, fishing mortality, has risen to four times that which the population can sustain. For white marlin (depicted below left), the situation is even worse. Abundance has declined to only 15 percent of the MSY level, and fishing mortality has risen to seven times that of the MSY level.  (This population is getting much too close to extinction.)

Since the commercial vessels are targeting other species whose populations are stronger and more numerous, the incidental kill of marlin will continue until it becomes unprofitable to target swordfish and the larger tunas. Swordfish and particularly yellowfin tuna populations can withstand a great deal more commercial fishing pressure before they are no longer economically viable. (Yellowfin are thought to be at about the MSY level.) Unfortunately, neither blue nor white marlin will be able to survive this continued pressure. They are already too close to the brink of extinction.

If the recent population trends are extended, blue marlin will approach extinction in about seven years (before 2008) and white marlin may slip over the edge into extinction even sooner - in only two to three years (by 2003). 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 percent of the MSY level). Passing such a threshold means there are too few adult breeders to replace the population, which can then spiral ever faster towards extinction. ICCAT's scientists do not specify the point of no return, but it is below the point at which recruitment failure is begun. It is quite possible that white marlin, at 15 percent of MSY, have already passed the point of no return, and that we may not even be able to save them from extinction.

The recreational fishing community can set a good example by doing what it can to reduce unnecessary mortality. The largest individuals, females capable of producing the most eggs, should be protected above all other size classes. (Like swordfish, male blue marlin rarely exceed 200 pounds) Sport fishermen and tournaments should continue to promote catch-and-release and adoption of non-offset circle hooks to prevent foul hooking and serious internal injury when using live bait. Both marlin are in such immediate danger that neither should be harassed during their critically important spring and early summer spawning period. (See Chambers and Associates' website - www.Chambers-Associates.org -  for maps showing their locations.) Fighting repeatedly for their lives may rob them of the valuable energy needed to avoid predators and for successful spawning.

The only meaningful solution is to dramatically and immediately reduce the killing of both marlin species by the international commercial fleets. Since half of all billfish caught on longlines are still alive when they arrive at the vessel, substantial progress toward recovery can be gained by safely releasing all live billfish. Seeking ICCAT adoption of this principle should be a primary objective of U.S. delegation this year. Total mortality should be reduced sufficiently to allow the stocks to recover to the MSY level within 10 years. The major source of mortality - the use of non-selective gear (drift longlines and drift gillnets) by commercial fishing interests - should be prohibited in these stocks' key spawning, nursery and feeding areas by international agreement.

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