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Learn more about the Ross Sea
In October 2016, after four years of deliberation, the body governing resource exploitation in the Southern Ocean (CCAMLR, Commission for the Conservation of Antarctic Marine Living Resources) declared the designation of the Ross Sea Region Marine Protected Area. For the previous 15 years, scientists who have conducted intensive research in the Ross Sea had been urging CCAMLR to set the Ross Sea aside from exploitation and preserve it as a unique place and natural laboratory especially to understand better the effects of climate change. The Ross Sea that they had in mind entails the waters overlying the Ross Sea continental shelf and continental slope (see Figure 1). The Ross Sea is bounded on the west by Victoria Land, on the south by the Ross Ice Shelf (largest continental glacier on Earth), on the east by Marie Byrd Land, and to the north by the continental slope (where depths descend from 800 to about 3000 m, the aquamarine color in the figure). Well, actually the ocean beneath the Ice Shelf is part of the Ross Sea, too. The continental shelf is composed of banks and troughs, which are bathed by what is known as Ross Sea Surface Water (unique combination of temperature and salinity). At ~598,000 km2, the Ross Sea is about 2.9% of the Southern Ocean, the ocean that surrounds Antarctica, and about the size of southern France. It is covered by sea ice for 8 months of the year, except for a few areas of open water, generated by the wind or currents, called polynyas.
Within these bounds, until 1996 there had been no known commercial fishing, no widespread pollution, no plastic debris, no toxic algae blooms, no anoxic dieoffs, and no invasions of alien organisms; an independent analysis had declared that the Ross Sea shelf and slope was the least affected stretch of ocean on the planet. Therefore, climate change was the only major force operating to change it. More than 400 species, mostly of benthic organisms, had been first described from Ross Sea specimens (that is, the Ross Sea is the ‘type locality’ of each of these organisms, a marker against which to gauge the effects of climate change), and more than 40 of them are found nowhere else including several species of fish. While whaling during the 1920s had removed blue whales from slope waters, and whaling during the 1970s had removed large numbers of minke whales, the minke whales had recovered by the 1990s and the blue whales’ recovery, much slower, is underway. Finally, the Ross Sea is home to about:
It also is a center of concentration of what has been called ‘the shark of the Antarctic,’ the Antarctic toothfish (aka Chilean sea bass), which reaches 2 m in length and weights up to 100 kg, and is confined to the southernmost reaches of the Southern Ocean where it can survive owing to ‘antifreeze’ in its blood. Certainly the concentration of life represented by these incredibly abundant ‘mesopredators’ --- birds, mammals and large fish --- is related to the fact that almost 30% of the primary production of the entire Southern Ocean is contributed by the Ross Sea, especially its diatoms. From this production comes an abundant prey resource to sustain these creatures. Truly the Ross Sea is a remarkable place!
Summaries of the distribution of these abundant birds, mammals and large fish, Figure 2, show the critical importance of the entire Ross Sea shelf and slope to the annual, life histories of this community of creatures, along with their prey. Different species concentrate different activities, all important, in different parts of the Ross Sea depending on season.
The realization that the Ross Sea is a special place, however, had little influence on persons engaged in the Antarctic toothfish industry. In 1996-97, a New Zealand fishing vessel initiated an exploratory fishery that found abundant large Antarctic toothfish in the Ross Sea. Subsequently, vessels from additional CCAMLR and non-CCAMLR countries joined the fishery, and the CAMLR Commission, in consultation with its Scientific Committee, instituted a management program that (1) assumed that there were no dependent or related species that could be affected by the fishery, and (2) set as its goal achieving maximum sustainable catches by reducing the spawning biomass (i.e., the big fish) by 50% by 2030. This means and has been shown that the fish would be decreasing in size and age, on average, so that the proportion of the population that can spawn would decrease and its reproductive potential would become less. According to theory, rarely shown to be true, the small fish would grow faster in the face of less competition for food. Since inception, upwards of 3500 tonnes of toothfish have been extracted from the Ross Sea region each year. The fishing occurs where depths are 800-1200 meters, especially the slope and deeper troughs of the Ross Sea shelf; this is where adult fish lie biding their time during summer, below the depth of air breathing predators, awaiting the return of the sea ice.
Much of the Ross Sea shelf had already become protected by CCAMLR in order to prevent longlines and trawls from destroying the ‘forests’ of benthic organisms that inhabit the ocean floor in shallow areas.
Here (Figure 3) is a photograph of an Antarctic toothfish hiding beneath an invertebrate-encrusted rock, 474 meters deep on the Ross Sea shelf (arrow points to tennis ball, attached to camera array for size scale; photo courtesy J. Eastman). These hiding places are destroyed by longlines, with little chance for recovery as replacement rates of benthic invertebrates in the cold Southern Ocean are measured in terms of multiple decades. Truly these organisms are highly vulnerable to molestation.
The protected shallow areas or banks of the Ross Sea are shown in yellow in the following Figure 4, that is, in areas where depths are shallower than 550 meters, no trawling or longlining is allowed, not just in the Ross Sea but throughout the Southern Ocean. However, shallow banks are rare in most Antarctic coastal waters, except for the broad continental shelf of the Ross Sea, and thus a large share of the Ross Sea became protected as of 2009. In the figure below, CM refers to the CCAMLR ‘conservation measure’ involved in benthic community protection; ASPA refers to an Antarctic Specially Protected Area, under the Antarctic Treaty, that includes a marine component; and the green is a seal conservation zone under the Conservation of Seals treaty.
Concerned about harm to the Ross Sea ecosystem by the toothfish fishery, and not just its benthos, workshops organized and attended by Ross Sea scientists were held in May 2009, at the International Marine Conservation Congress (Fairfax, VA), and again in March 2012 (La Jolla, CA). Those scientists attending represented more than 200 person years of Ross Sea research experience, and they deliberated over what biologically meaningful boundaries of an MPA should be asked for and why. The result is shown in the next figure (5), which is a summary of areas by priority that should be included in the MPA, anticipating that during negotiation there would be questions about the relative importance of different parts of the Ross Sea. Of course, much was written to elaborate on the reasoning behind identifying these areas. [pdf#1] [pdf#2]
The U.S. Department of State, which is the arm of the U.S. government that oversees international treaties, on the basis of the conclusions of the marine scientists at these workshops, in 2012 offered a proposal to CCAMLR, which is shown in Figure 6, below . The proposed boundary of the MPA is in dark blue; the areas of especially high biological activity are shown in light blue shading (compare with Figure 2, above). The yellow dots represent sites where longlines have been frequently deployed in order to catch Antarctic toothfish.
As can be seen in these figures --- the high priority fishing areas (concentrated yellow dots) are also the high priority areas for protection of “the structure and function of the Ross Sea marine ecosystem” (as called for in the proposal; compare again with Figures 2 and 5 above). In this proposal, the US State Department assumed that it would be useless arguing for full protection of the Ross Sea continental slope, given the power of the fishing industry in CCAMLR, and so the proposal excluded the most favored fishing area, which is on either side of Pennell Bank (see Figure 1 above). However, the proposal asked that a portion of the eastern slope, where fishing had been conducted, would be included within the MPA as a ‘control’ to gauge the effects of fishing on the ecosystem, separating effects from climate change. This proposal also included most of the seamounts to the north of the Ross Sea where it is thought that Antarctic toothfish spawn --- protecting the breeding stock is a no brainer, and is common practice when managing long-lived species and when Marine Protected Areas are being used to protect portions of populations of fished species.
The fishing countries, which are in the large majority at CCAMLR, viewed the original US proposal as a non-starter as it took away too much fishing area. While the fishing industry could care less about areas where depths are greater than 2000 meters, they were resistant to giving up their favorite fishing areas, including the spawning seamounts (where the biggest fish lie, and are closest to home port). To reach a consensus agreement by the 25 CCAMLR members, the Ross Sea region MPA represented a compromise between opposite views. The agreed Ross Sea Region MPA is shown in the next figure.
In this agreed-to MPA, the toothfish fishing industry gave up very little. The annual take of toothfish will remain ~3500 tonnes in this region, mainly with fishing continuing along the shelf break and at the seamounts. In compensation, and supposedly to protect ‘biodiversity,’ other areas deeper than 2000 m were tacked onto the proposal so that it could boast of its large size, i.e. ‘the largest MPA in the world.’ Much of the area tacked on is not in the Ross Sea, and the Balleny and Scott islands can protect themselves --- surrounded by sea ice for a large part of the year and really difficult landing, as they rise vertically from 3000 m depths; and Balleny Islands already an ASPA. The fishing industry could care less about these deeper areas of ocean.
For other concessions to the fishing industry, a ‘Krill Research Zone’ (KRZ) was added, with the intended research being whether krill could be caught in this area at economically feasible quantities. The KRZ is part of the summer home of several thousand humpback whales, whose population has been recovering from whaling and would be competing for the krill, as would also blue whales, recovering very slowly. Also carved out of the ideal MPA (see Figures 5 and 6, above) was the section of the continental slope that is called the ‘Special Research Zone’ (SRZ). The research in this area, involving commercial fishing, would entail tagging-and-releasing 3 toothfish per tonne, rather than the one fish per tonne required by CCAMLR everywhere else. This contributes to the tag-and-release program that is so far the only source of data used by CCAMLR to gauge the stock size and effect of fishing. In addition, the MPA would not preclude ‘scientific whaling’ under the International Whaling Convention.
Finally, in still another concession, the current Ross Sea Region MPA designation is in place for just 35 years, and then the members of CCAMLR decide if it should remain, be reduced or be expanded. While this time period will offer protection for some species, it is less than the life span of toothfish, skuas, killer whales, blue whales, and several times less than the lifespans of many of the benthic invertebrates that cover the Ross Sea floor. Continued removal of the large toothfish, the target of the fishery, will continue to change ecological relationships within the Ross Sea ecosystem. Given that CCAMLR requires the minimization of activities that risk changes in the marine ecosystem that are not reversible over two or three decades, the 35 year time limit is a bit inconsistent with CCAMLR policy.
Besides the short time frame, while billed as the largest MPA in the world, the size of an MPA should not be measured just by the number of its square kilometers, but rather by what size and areas are necessary to encompass the home ranges of the species that make up its community. The current MPA falls short in this respect, especially in the case of Antarctic toothfish, which mature in waters over the shelf and slope, where they compete with penguins and seals for food and are the prey of seals and killer whales, and spawn over the northern sea mounts. The proponents of the initial MPA plan knew about the significance of these time and space attributes to marine protection, but had to compromise over geopolitics to get any agreement at all. Even accomplishing that required extra effort from the US Department of State and various public groups such as The Last Ocean Trust, UN Ocean Ambassador program, and the Antarctic and Southern Ocean Coalition (umbrella within CCAMLR for organizations such as Pew Charitable Trusts, Greenpeace, etc.).
For sure, the Ross Sea Region MPA can be considered a victory. The shelf is now protected further, including its deep troughs. Establishing an important precedent, waters under the Ross Ice Shelf are included in the MPA as well. All that is good. Although there are no intentions yet of fishing for the main prey of the predators that inhabit the shelf, i.e. Antarctic silverfish and crystal krill, the summertime foraging areas of all the penguin and seals that breed along Victoria Land and western Marie Byrd Land, as well as some of the areas where penguins regain condition and molt before dealing with the winter (extreme eastern Ross Sea slope; see Figure 2, above), are now protected from fishing. More importantly, the rich communities of invertebrate organisms that compose the ‘forests’ on the Ross Sea floor, many of these organisms unique to the Ross Sea (including small fish), are now protected, at least for the next few decades (see Figures 3, 8).
Figure 8. Mind-blowing concentrations of Antarctic scallops, and other creatures, like those shown here, are found dispersed around the Ross Sea shelf and are now protected from exploitation (photo H. Kaiser).