SEAFOOD SCAM

Fisherman with Patagonian toothfish, aka Chilean sea bass. Credit: Paul A. Sutherland/NGS.

 

The Marine Stewardship Council (MSC) just racked up another black eye from their sustainable seafood program. 

According to a new paper in Current Biology, nearly one of every five fillets of Chilean sea bass genetically sampled were either not Chilean sea bass, or else not from the only area deemed to have a sustainable fishery—the South Georgia Islands/Shag Rocks fishery.

I've written before—here and at MoJo Blue Marble—about other problems emerging with the MSC, casting doubts on its stretchy definition of 'sustainable.'

South Georgia Island. Via.

  

Here's what the authors of the Current Biology paper have to say about the Chilean sea bass fishery:

The decline and collapse of many of the world's fisheries has led to the implementation of social marketing that promotes the consumption of sustainably harvested seafood. Because the success of this strategy depends on supply chain integrity, we investigated the accuracy of eco-labels for Patagonian toothfish, marketed as 'Chilean sea bass' (Dissostichus eleginoides), by genetically analyzing retail fish bearing certification labels from the Marine Stewardship Council.  

They found:

• 8 percent (3 of 36) of the fish labeled as MSC-certified Chilean sea bass were actually other species.
• 15 percent (5 of 33 samples) that were Chilean sea bass were unlikely to have come from the South George Islands/Shag Rocks fishery.

Chilean sea bass mitochondrial DNA (mtDNA) haplotype
frequencies. Pie diagrams (sample sizes within) show the frequencies of mtDNA haplotypes from locations marked by yellow stars and for the retail MSC sample which was ostensibly harvested from the South Georgia/Shag Rocks fishery (SGSR). The size of each pie is proportional to the sample sizes, including the retail MSC sample. The heavy dashed blue line indicates the position of the Antarctic Polar Front; gray lines and italicized numbers denote United Nations Food and Agriculture (FAO) fishing areas. Credit: P.B. Marko, et al. Current Biology. DOI:10.1016/j.cub.2011.07.006.

 

Chilean sea bass are big (≥200 kilograms/440 pounds and up to 2.3-meters/7.5-feet long) and long lived (50 years, with sexual maturity as late as 20 years)—two guarantors of vulnerability to overfishing. Nature News reports:

Catching them "is not like fishing for fish—it's almost like logging for trees", says Stephen Palumbi, a marine population biologist at Stanford University in California, who was not involved with the study. "It takes that long for these fish to grow up and be ready for market. That's why the fish got in trouble."

Meanwhile Science Now reports the views of Lars Gulbrandsen at the Fridtjof Nansen Institute in Lysaker, Norway, who studies eco-certification:

"The high rate of mislabeling revealed in this study could potentially undermine MSC's reputation as the gold standard for environmentally friendly fishing."

Chilean sea bass (Dissostichus eleginoides). Via.

  

The study authors conclude:

Although social marketing has the potential to positively impact threatened species by guiding consumers towards sustainable fisheries, our study showed that retail labeling of MSC-certified Chilean sea bass was inaccurate and that country-of-origin labelling was highly misleading. With respect to certified sustainable fisheries, mislabeling ultimately results in misplaced consumer demand for uncertified fisheries, thereby undermining the most basic goal of this conservation strategy.

Credit: Monterey Bay Aquarium Seafood Watch.

   
The Monterey Bay Aquarium's Seafood Watch program (with cool app) lists Chilean sea bass as a fish to avoid due to high mercury and dodgy fishing methods:

Illegal, unreported and unregulated fishing has depleted some populations of Chilean seabass. In addition, some Chilean seabass is caught using unmodified bottom longlines, which hook and drown thousands of seabirds each year, most notably endangered albatross. A portion of the Chilean seabass fishery is certified as sustainable to the standard of the Marine Stewardship Council. These certified fisheries are not evaluated in the Seafood Watch report and are not covered under the general "Avoid" recommendation.

And now we know what to make of the "certified sustainable" fisheries.
 

Wandering albatross. Credit: Eric van Poppel via Wikimedia Commons.

 
The paper:

• ♥ Peter B. Marko, Holly A. Nance, and Kimberly D. Guynn. Genetic detection of mislabeled fish from a certified sustainable fishery. Current Biology (2011). DOI:10.1016/j.cub.2011.07.006.

♥ Open-access papers.

EXPANDING OCEANS: BATIKS OF MARY EDNA FRASER

Great Barrier Reef II (Australia), 108" x 45," batik on silk. Mary Edna Fraser.

  

Artist Mary Edna Fraser has a new exhibit called Our Expanding Oceans at the North Carolina Museum of Natural Sciences in Raleigh. These are beautiful batik pieces designed to use art as a vehicle to share scientific information. Many are featured in a new book, Global Climate Change: A Primer, by Orrin and Keith Pilkey, Duke University Press:

Global warming endangers coral reefs in two ways. If sea level rise is too rapid the reefs will drown and if maximum summer temperatures are too high, fatal coral bleaching (caused by loss of the symbiotic zooxanthellae algae) may occur. Bleaching has already killed portions of the Great Barrier reefs. Fortunately if conditions are right, reefs can recover. —Orrin Pilkey 

Mary Edna Fraser tells me of the outcome of her first snorkeling adventure in 2007:

And it was my initiation into underwater photography as well.  The batik is a synthesis of that experience which was like flying under water with colors and shapes constantly in motion. This aquatic excursion changed my life forever.

Charleston Airborne Flooded, 95.5" x 35," batik on silk. Mary Edna Fraser.

  

The piece above is of Fraser's hometown, Charleston, South Carolina. It's based on a NOAA projection of a 4.5-foot/1.4-meter rise in sea level by the year 2100:

The dark green band along this Charleston regional shoreline is the area that will be flooded after a 4.5 foot sea level rise. The barrier islands along the outer coast have largely disappeared in this projection, though in reality the islands might instead grow narrower and migrate toward the mainland. Anyone planning on a property purchase in this area might be well-served by this beautiful piece of art. Already sea level rise has made the storm water runoff system ineffective and unable to drain the city during a simultaneous heavy rain and high tide. As the shoreline moves inland, so will future storm surge levels and storm waves. All told, coastal living in the lower coastal plain faces a challenging future. —Orrin Pilkey

You can see more of Fraser's art-science mashups here.

AFTER THE CORAL BLEACHING, THE WINNER IS...

The winners: Acropora corals. Credit: Albert Kok at Wikimedia Commons. 

  
After 14 years of tracking coral colonies at Sesoko Island, Okinawa, Japan, through two coral bleaching episodes—1998 and 2001—the big coral winners and losers on the reef have been announced...

• The winners: Porites, faviids, and Acropora colonies

• The losers: pocilloporids

Except it's not that simple, the authors of a new study warn. Since 14 years is hardly the long long run.

The losers: Pocillopora corals. Credit: Mila Zinkova at Wikimedia Commons.

  
In a new paper in the current issue of MEPS we get a sense of what happens in the short long run after of a big coral bleaching event. 

Background: Coral bleaching occurs when water temperatures rise, stressing the coral animals enough to expel their symbiotic partners—the zooxanthellae. These single-celled plants give corals their beautiful colors and help feed them through photosynthesis (as if we could grow rice inside our bodies). In some plant-animal partnerships, the zooxanthellae entirely feed their corals.

Zooxanthellae (yellowish streaks) cells embedded in coral polyps. Via.

 
In the past 30 years, rising sea surface temperatures have stressed and bleached corals worldwide. 

Yet few researchers have looked at what recovery looks like over time—whether the species of corals that fare better in the short term also fare better in the long term.

A partially bleached faviid coral. Credit: Nhobgood at Wikimedia Commons.

At Sesoko Island, the researchers found that although species richness recovered after 10 years, the composition of coral species on the reef had changed. The pocilloporids were nearly completely gone. Among their other findings:

• Short-term winners were generally thermally tolerant encrusting and massive corals, like Porites and faviids and small (<5 cm/2 in) Acropora colonies. 
• Ten years after the bleaching the community was still structurally different, consisting of a combination of survivors that were either:

1. Tolerant to heat stress
2. Surviving as fragments of colonies that experienced rapid regrowth 
3. Regionally persistent colonies that recruited locally

Credit: R. van Woesik, et al. MEPS. DOI:10.3354/meps09203.

  
The last point is interesting because it means that having healthy reef neighbors enabled some species to recover—thanks to seeding from nearby islands. 

Yet even the short long term winners may not survive the long long term. The authors close with these strongly cautionary words: 

The present study suggests that as the oceans warm even further, the coral assemblages will change. Reefs may soon essentially only support heat-tolerant coral species. The narrowing of genetic diversity within communities is likely to impact other dependent species such as fishes and crustaceans, especially if important reef-building branched corals, such as Acropora, Stylophora, Pocillopora, and Porites cylindrica, become rare on account of their inherent sensitivity to thermal stress. Bleaching may also become punctuated over the next several decades. In the short term, the remnant yet hardy populations may show some resistance to the higher water temperatures, and bleaching may be reduced for a decade or more if Acropora and pocilloporids are removed from local reefs. However, reduced bleaching may give false hope because once the inevitable temperature threshold of the remnant communities is surpassed, widespread coral mortality will follow. Given that even the hardiest coral genera have their limits, global temperature increases will eventually lead to an exponential rate of local, regional and global reduction of coral species. To what extent this reduction of coral species will occur will depend on how rapidly and by how much the ocean temperatures increase, which depends on the fossil-fuel-emission pathway that humans choose.

  

Coral recovery underway on a reef. Credit: Bruno de Giusti at Wikimedia Commons.

The paper:

• van Woesik R, Sakai K, Ganase A, Loya Y (2011) Revisiting the winners and the losers a decade after coral bleaching. Mar Ecol Prog Ser 434:67-76. DOI:10.3354/meps09203.

THE LAST GREAT WILDERNESS

A sea whip found deep on the slope of the Gulf of Mexico. Credit: Aquapix and Expedition to the Deep Slope 2007.

The next chapter in our thinking about the oceans is analyzed in a new paper in PLoS ONE.

The deep sea—largest of Earth's ecosystems and its last great wilderness—has been spared much of what's befallen the rest of the ocean in the last century, thanks to its remoteness. But not any more.

Technology is rapidly undressing this veiled realm, allowing us to exploit its fisheries, hydrocarbons, and minerals at depths below 2,000 meters/6,562 feet. The authors write:

[T]he challenges facing the deep sea are large and accelerating, providing a new imperative for the science community, industry and national and international organizations to work together to develop successful exploitation management and conservation of the deep-sea ecosystem.

Anemone attached to a carbonate boulder at 1,500 meters/4,921 feet depth in the Gulf of Mexico. Credit: Aquapix and Expedition to the Deep Slope 2007, NOAA-OE.

 
The paper represents the combined thinking of 11 researchers from around the world—Spain, UK, Norway, New Zealand, Mexico, US, and France—including some of the biggest names in deep-sea research. Coauthor Lisa Levin, recently made the Director of the Center for Marine Biodiversity and Conservation at the Scripps Institution of Oceanography, was featured in my biodiversity article in MoJo, Gone.

Based on their own extensive experience, combined with published scientific papers, the authors provide a semi-quantitative analysis of the scale of of human activities past, present, and future.

Synergies among anthropogenic impacts on deep-sea habitats. The lines link impacts that, when found together, have a synergistic effect on habitats or faunal communities. The lines are color coded showing the direction of the synergy. LLRW=low-level radioactive waste; CFCs=chlorofluorocarbons; PAHs= polycyclic aromatic hydrocarbons. Credit: Ramirez-Llodra E, et al. PLoS ONE. DOI:10.1371/journal.pone.0022588

 
They assessed 28 major anthropogenic impacts (above), grouped into 3 main categories—disposal, exploitation, and climate change. They then examined those effects on 12 deep-sea habitats (below). I've added links to explanations of the terms:

• Mid-ocean ridges, characterized by benthic sessile fauna and localised demersal and pelagic communities.
• Sedimentary slope (excluding other specific communities found on slopes such as cold-water corals, seeps, oxygen minimum zones), characterized by demersal fauna as well as epifaunal and infaunal benthos
• Canyons, with a high degree of habitat heterogeneity and diverse fauna varying with substratum: sessile benthos and demersal fauna characterize hard bottoms, while mobile epifauna, infauna and demersal fauna abound in association with soft sediments.
• Seamounts, characterized by sessile benthos and abundant localised pelagic communities.
• Cold-water coral habitats, including the frame building corals and associated species.
• Active hydrothermal vents, characterized by benthic fauna with a high degree of endemicity.
• Cold seeps, characterized by benthic fauna with a relatively high degree of endemicity
• Oxygen minimum zones abutting margins, characterized by specialized benthic fauna.
• Abyssal plains, characterized by mobile epifauna and infauna.
• Manganese-nodule provinces, specific habitat on abyssal plains, characterized by sessile and mobile epifauna and infauna.
• Trenches, characterized by demersal megafauna and infauna.
• Bathypelagic water column, characterized by mid-water species.

Deepwater Horizon oil slick in the Gulf of Mexico, 2010. (Top) photo of the oil being discharged in the water column; (Bottom) a coral in the deep Gulf of Mexico, with attached ophiuroid, covered with oil. Credit: Lophelia II 2010, NOAA OER and BOEMRE.

 
They conclude that a sea-change is underway:

Based on the current knowledge available in the scientific community and expert estimates, we suggest that the overall anthropogenic impact in the deep sea is increasing, and has evolved from mainly disposal and dumping in the late 20th century, to exploitation in the early 21st century...

During the remainder of the current century, we predict that the major impact in the deep sea will be climate change, affecting the oceans globally through direct effects on the habitat and fauna as well as through synergies with other human activities.

Unexploded ordinance on the seafloor in the Gulf of Mexico. Credit: Expedition to the Deep Slope 2007, NOAA-OE.

  
The deep-sea habitats most affected at present are:

1. Sediment slopes, mainly affected by fishing—trawling, longlining, and ghost fishing caused by lost or discarded gear
2. Cold-water corals, which are especially vulnerable to damage from fishing gear that can destroy whole communities
3. Canyons, mainly affected by fishing 
4. Oxygen-minimum zones, most threatened by by climate change and significant increases in hypoxia. 

Macro image of tiny octocorals at 1,500meters/4,921 feet in the Gulf of Mexico depth. Credit: Courtesy of Aquapix and Expedition to the Deep Slope 2007, NOAA-OE.

The paper provides a valuable summary of protected deep-sea habits worldwide. And it describes the biggest hurdle in the life-cycle of any protected ocean area—the ability of slow-funded science to keep up with the big money of industry and development. Add bureaucratic foot-dragging into the mix and the race to protect the real value of the deep becomes even more lopsided.
 
They authors close with a call to arms, suggesting that human encroachment into the deep sea creates a new conservation imperative... and that effective stewardship will require continued exploration, basic scientific research, monitoring, and conservation measures—all at the same time.

Conservation in the deep sea offers challenges in the form of knowledge gaps, climate change uncertainties, shifting jurisdictions and significant enforcement difficulties. With time, technological advances can help address these challenges. It remains to be seen whether new approaches must be developed to conserve the biodiversity and ecosystem services we value in the deepest half of the planet.

Credit: wrobell at Wikimedia Commons.

 
The paper:

• ♥ Ramirez-Llodra E, Tyler PA, Baker MC, Bergstad OA, Clark MR, et al. (2011) Man and the Last Great Wilderness: Human Impact on the Deep Sea. PLoS ONE 6(8): e22588. doi:10.1371/journal.pone.0022588

♥ Open-access papers.

THE MEMORIES OF OLD FISHERS

There's an interesting paper just out in PLoS ONE assessing whether or not the memories of old fishers could be useful to science. Specifically, whether their recollections correlate with other fisheries data from recent decades.

The authors write:

Population declines and the extinction of marine organisms may be largely underestimated due to the difficulties involved in making scientific observations. However, data sources other than scientific time-series have proven useful in providing relevant information to marine scientists in cases that are normally considered "data-poor." Some studies have used traditional (or local) ecological knowledge to reconstruct temporal population trends and discover near-extinctions of marine fauna, while studies that compare the results from scientific research with evidence based on fishers' experience have shown that both sources of knowledge give similar results and can be used to detect the essential trends.

(Photo above by Steve Evans via Wikimedia Commons.)

(Monk seal. Via.)

To investigate, the researchers delved into the memories of 106 retired trawl fishers in Italy, Spain and Greece, seeking their impressions of the abundance of long-lived marine species—dolphins, whales, monk seals, marine turtles, and sharks—in the Mediterranean.

During the interviews, the old dudes (pretty sure they were all dudes) were asked to rank abundance of these animals group during three 20-year periods between 1940 and 1999.

 

Their perceptions were based on two indicators:

• Frequency of sightings
• Frequency of catches (incidental or intentional) 

(Via.)

Specifically, they were asked about:

• Intentional catches of dolphins 
• Intentional catches of turtles
  
• Sightings of dolphins, whales, seals, or turtles
• Relative catches of sharks/cartilaginous fishes

Their answers could be: "never," "occasional," "frequent," or "very frequent."

(Trends in catches and sightings of large marine fauna, all areas combined. Credit: Francesc Maynou, et al. PLoS ONE. DOI:10.1371/journal.pone.0021818.t001. Larger view here.)

The results were interesting. And sad.

• The frequency of encounters between large marine fauna and fishers declined throughout the latter half of the 20th century.
• The decline continues at the beginning of the 21st century (except in Greece, where some dolphins are experiencing population increases).  
• The commercial catches of sharks and other cartilaginous fishes decreased significantly.  

The authors note that the abundance of monk seal and whales was already so low in the 20th century that the interview data were insufficient for a quantitative analysis.
  

(Angelshark. Photo by Philippe Guillaume via Wikimedia Commons.)

Here's what the fishers' memories revealed about recent extinctions:

[S]moothhounds Mustelus mustelus [a kind of shark] are likely to have disappeared in the Catalan Sea before 1979, and angelsharks Squatina squatina before 1959. In western Italy, angelsharks would have disappeared by the early 1980s near the mainland and the mid-1980s in Sardinia. Smoothhounds became functionally extinct in 1990 in Italy and Greece, with only sporadic records thereafter. The sturgeon Acipenser acipenser had become extinct in the North Adriatic by 1966.

(Photo by catrien via Flickr.)

Bottom line is that fishers are good observers and a largely untapped treasure trove of fish tales about the health of marine ecosystems.

If we accept that commercial trawl fishers are independent observers of the marine system, [our] results suggest that the abundance of large marine fauna has decreased considerably during the 20th century in the Mediterranean Sea (in agreement with the results of other studies), and therefore fishers' observations during a lifetime of professional activity can provide a qualitative measure of this decline.

(Photo via.)

Fish tails welcome too.

Maynou, F., Sbrana, M., Sartor, P., Maravelias, C., Kavadas, S., Damalas, D., Cartes, J., & Osio, G. (2011). Estimating Trends of Population Decline in Long-Lived Marine Species in the Mediterranean Sea Based on Fishers' Perceptions PLoS ONE, 6 (7) DOI: 10.1371/journal.pone.0021818

ATTACK OF THE COOKIECUTTER SHARK!

*Warning: graphic images below.*

Ouch. All bite and no bark. The first ever recorded instance of a human bitten by a cookiecutter shark is described in a paper now online in early view in Pacific Science.

An unfortunate human swimmer on a 47.5 kilometer/29.5 mile haul across the Alenuihaha Channel between the Hawaiian islands of Hawai‘i and Maui got nailed twice by this fearsomely ninjalike denizen of the deep, Isistius sp.

(Photo above: cookiecutter shark. Via FMNH.)

(Two cookiecutter shark bites in a pomfret. Credit: PIRO-NOAA Observer Program via Wikimedia Commons.) 

If you've spent any time at sea outside polar waters, chances are you've seen the toothwork of this gnarly little predator. It leaves deep round scars on whales, dolphins, tuna, billfishes, squids, and other larger marine life.

As Kramer used to say: Nature, she is a mad scientist... and never more so than with the hunting technique devised by the cookiecutter shark. Here's how FishBase describes it:

The cookie cutter shark has specialized suctorial lips and a strongly modified pharynx that allow it to attach to the sides of it prey. It then drives its saw-like lower dentition into the skin and flesh of its victim, twists about to cut out a conical plug of flesh, then pull free with the plug cradled by its scoop-like lower jaw and held by the hook-like upper teeth.

(Cookiecutter sharks live in the mesopelagic zone and below and swim to the surface to feed at night. Credit: Nicholas Felton via Mother Jones.)

Cookie cutter sharks spend the daylight hours below the cusp of darkness—that is, below 1,000 meters/3,280 feet. They migrate to or near the surface at night, travelling 2,000-3,000 meters/6,560-9,840 feet on a diel cycle. That's nearly two miles a day for a fish that maxes out at 56 centimeters/22 inches in length.

They ascend and descend alongside a massive community of marine life known as the deep scattering layer. (I wrote extensively about this community in my Gulf of Mexico oil piece in Mother Jones last year called The BP Cover-Up.) 

(Scars on a dead Gray's beaked whale, Mesoplodon grayi, possibly from cookiecutter shark bites. Credit: Avenue via Wikimedia Commons.)

But here the mad-scientist design gets even madder. The skins of cookiecutter sharks glow strongly bioluminescent—reported to radiate light for as long as three hours after death—part of their underwater camouflage wherein they hide among schools of glowing squid. 

And no one likes squid better than many of the cetaceans. When whales and dolphins attack squid, cookiecutter sharks ambush the ambushers, darting out to steal a plug of flesh, then disappearing back into the bioluminescent background.

(Bioluminescent squid. Via.)

The human swimmer off Hawaii was attacked at night when the stern deck lights from the escort boat were lit and shortly after the escort kayak lit red and green bow lights. Here's what the Pacific Science paper says:

About ten minutes after the kayak's bow light was turned on, the victim was bumped by a squid. Over the next twenty minutes he was bumped by squid two or three more times in the shoulder and side areas at irregular intervals. At 2003 hrs, the victim suddenly felt a very sharp pain on his lower chest, and assumed it was a triggerfish bite. The sensation was instantaneous and localized, like a pin prick, and felt like a bite from a very small mouth. The victim yelped and swam over to the kayak, turned off the bow light, and was in the process of getting into the kayak with his legs vertical and "egg-beatering" to maintain position when he felt something bite his left calf. The time interval between the two bites was less than 15 seconds. The sensation of the bite to the leg was slightly more prolonged (but still very quick, less than a second), involved some pressure, and was less painful than the chest bite.

After extensive surgery, the deep leg wound was plugged, grafted, and healed. You can read the whole paper and see more images here.

(Top photo: shallow chest wounds. Bottom photo: deep calf wound. Credit: Honebrink, R., R. Buch, P. Galpin and G. H. Burgess. Pacific Science.)

Seems like FishBase will have to amend their listing for cookie cutter sharks. Currently it reads:

Not dangerous to people because of its small size and habitat preferences.

The Pacific Science paper concludes:

Humans entering pelagic waters at twilight and nighttime hours in areas of Isistius sp. occurrence should do so knowing that cookiecutter sharks are a potential danger, particularly during periods of strong moonlight, in areas of manmade illumination, or in the presence of bioluminescent organisms.  

RIGHT WHALES DECODED

(Southern right whale. Credit: © Brian J. Skerry / National Geographic Stock. Via the World Wildlife Fund.)

An interesting new paper in MEPS (Marine Ecology Progress Series) on the southern right whales of New Zealand and Australia.

Background: All right whales, north and south, were taxed hard and early by human whalers—the "right" whales to hunt because their high blubber content made them likely to float after death and because they frequented near-shore waters.

That made them easy to get to even in the days of rowing.

(A painting, artist unknown, showing the hunting of right whales. La Baleine. The Whale, circa 1840. Credit: Wikimedia Commons.)

Some 150,000 Southern Hemisphere right whales (Eubalaena australis) were killed by 19th-century whalers and by illegal 20th-century Soviet whalers—driving the species to the brink of extinction.

Around Australia and New Zealand, hunting peaked in the 1830s-1840s, after which the species was commercially extinct.

(Geographic range of the southern right whale. Via the Red List.)

The latest IUCN estimate of southern right whales dates back to 1997 when they calculated a population of 7,500 individuals. 

At that time, several breeding populations (in Argentina/Brazil, South Africa, and Australia) showed evidence of strong recovery, with a doubling time of 10-12 years.

Which means there might be a fair few more than 7,500 whales today.

(Southern right whale with calf. Credit: John Atkinson. Via Marine Science Today.)

According to the authors of the MEPS paper, no right whales were seen in the waters around mainland New Zealand for 35 years between 1928 and 1963. A few slowly returned. Yet as recently as 2005 less than 12 sexually mature females were found there.

But another group, known as the New Zealand subantarctic group, has a more robust population estimated at about 936 whales today. Forebears of this group were likely present in some small numbers even in the bleakest killing years.

(Credit: E. Carroll, et al, via MEPS.)

The authors of the MEPS paper wondered about the levels of relatedness between those two whale stocks in New Zealand, as well as among whales in Australia.

They used mitochondrial DNA and microsatellite genotypes to identify 707 individual whales and test them for genetic differentiation. You can see the breakdown of that analysis in the graphic above.

Their data, combined with historical evidence, led the researchers to hypothesize that individuals from the NZ subantarctic are slowly recolonizing mainland New Zealand waters, where a calving ground was obliterated in the 19th century.



(Southern right whale. Via.)

The genetic evidence also suggests that the whales of southeast Australian are a remnant stock—different from the whales of southwest Australia:

At the onset of whaling, southern right whales, in particular cows with calves, were found across the southern coast of Australia during the austral winter (IWC 1986). There was no real discontinuity in distribution or catch records to suggest subdivision of calving grounds in this region (IWC 1986). Based on the timing of catches at shore whaling stations during the 19th century, Dawbin (1986) proposed that southern right whales undertook 2 distinct patterns of migration along the southern coast of Australia during the austral winter. The southern right whales that migrated north along the east coast of Tasmania [the small island off the southeast tip of Australia, as seen in the graphic above] moved in a northeasterly direction up the coast of Victoria and New South Wales, while those that migrated north along the west coast of Tasmania moved from east to west along the southern coast of South and Western Australia. The latter pattern is still extant, based on the movement of photo-identified southern right whales and has been termed the 'counter-clockwise' migratory pattern (Kemper et al. 1997, Burnell 2001).

(The Southern Ocean. Credit: Connormah via Wikimedia Commons.)

They also found evidence that New Zealand and Australian right whales mingle in higher-latitude summer feeding grounds each austral spring—making the health of those cold Southern Ocean waters as important a component of recovery as the whales' breeding efforts.

And what epic efforts they are. Imagine a 12-foot-long penis—known colloquially as a sea snake—plus a tons' worth of testes per male. Mating becomes a sport of endurance. And sperm competition.

But you don't have to imagine it. As usual, just for us, David Attenborough respects the privacy of none.

Carroll, E., Patenaude, N., Alexander, A., Steel, D., Harcourt, R., Childerhouse, S., Smith, S., Bannister, J., Constantine, R., & Baker, C. (2011). Population structure and individual movement of southern right whales around New Zealand and Australia Marine Ecology Progress Series DOI: 10.3354/meps09145