The sound level of songs blue whales sing across the vast expanses of the ocean to attract potential mates has been steadily creeping downward for the past few decades, and a scientist at Scripps Institution of Oceanography at UC San Diego and his colleagues believe the trend may be good news for the population of the endangered marine mammal.

Mark McDonald of WhaleAcoustics in Bellvue, Colo., along with John Hildebrand of Scripps Oceanography and Sarah Mesnick of NOAA Fisheries Southwest Fisheries Science Center studied blue whale song data from around the world and discovered a downward curve in the pitch, or frequency, of the songs. The decline was tracked in blue whales across the globe, from off the Southern California coast to the Indian and Southern Oceans.

“The basic style of singing is the same, the tones are there, but the animal is shifting the frequency down over time. The more recent it is, the lower the frequency the animal is singing in, and we have found that in every song we have data for,” said Hildebrand, a professor of oceanography in the Marine Physical Laboratory at Scripps.

The study’s results are published in the most recent issue of the journal Endangered Species Research.

The researchers examined a list of possible causes for the frequency drop-from climate change to a rise in human-produced ocean noise-and believe it may be explained by the increase of blue whale numbers following bans on commercial whaling activities.

While the function of blue whale songs is not known and scientists have much more to learn, they do know that all singers have been determined to be males and that the high-intensity, or loud, and low-frequency songs propagate long distances across the ocean. Blue whales are widely dispersed during the breeding season and it is likely that songs function to advertise which species is singing and the location of the singing whale.

In the heyday of commercial whaling, as blue whale numbers plummeted, it may have been advantageous for males to sing higher frequency songs, the researchers believe, in order to maximize their transmission distance and their ability to locate potential mates (females) or competitors (other males).

“It may be that when (blue whale) densities go up, it’s not so far to get to the closest female, whereas back when they were depleted it may have been that the closest female was a long way away,” said Hildebrand.

In the 1960s, when blue whale numbers were substantially reduced and recordings of the animals were first made, there may have been a tradeoff in which the male suitors chose to sing higher frequencies that were louder and heard over greater distances, Hildebrand said. In more recent years, as population sizes have increased, it may now be more advantageous for males to sing songs that are lower in frequency rather than louder.

“When they make these songs they need to use most of the air in their lungs,” said Hildebrand. “It’s like an opera singer that sees how long he can hold a note. The (male) songs are made to impress the females and/or other males, so I think that’s how the boy blue whales are impressing the girls, or are showing off to other boys: by making a loud and long song.”

The scientists say the same downward pitch phenomenon may be true in other whales such as fin and humpbacks, but the blue whale song, with a comparatively easier song to analyze, is a good springboard to study other species. Hildebrand says such knowledge about whale songs could be important in monitoring whale populations and recovery efforts.

During the study the researchers analyzed thousands of blue whale songs divided into at least 10 worldwide regions. These include the Northeast, Southwest and Northwest Pacific Ocean; the North Atlantic; the Southern Ocean near Antarctica; and the North and Southeast Indian Ocean. Blue whale songs have been recorded for the last 45 years through scientific and military applications by seafloor seismometers tracking regional earthquakes and dedicated whale acoustic recording packages.

With the pages rolling it becomes quite apparent that there are a few conservation gems sprinkled throughout the paper and worthy of rehashing, or what a waste of my time in writing and yours in reading this post.   Success of marine protected areas, declining species, and the interconnectedness of species in an ecosystem are the themes/take home messages while the family Scaridae is the star, or victims, of the show. 

Scarids, or parrotfish, included 83 species at the time of my university courses (~90 species as of 2002) and are so named because their fused teeth resemble a parrot-like beak.  And it is this beak that is quite useful for biting off pieces of coral and algal fronds.  The bits are ground down in their massive pharyngeal mills and the algal cells are extracted.  As discussed by the authors, parrotfish fill a critical role in maintaining coral reef systems by controlling filamentous algae and Scleractinian corals, removing detritus, and digging through the surface of the reef thusly redistributing the ground calcareous pieces as sediment.

As Pacific Island populations grow, the demand for coral reef resources including the parrotfishes themselves increases dramatically.  Thus, it is not surprising that the fishing pressures have caused a total parrotfish population decline of 45% from 2004 to 2005 in the Pacific Island study area. But remember I said there were a few conservation gems…well it turns out communities in the Western Solomon Islands have begun to see the frightening trends and instituted management practices and community-based marine protected areas to curb the overfishing (and habitat degradation) problem.  Not only are their livelihoods on the line but the whole coral reef system.

The take home lesson is that community-based marine protected areas do in fact work, and is evident with the following results:

 -Parrotfish numbers/abundance in outside sites were significantly lower than inside community-based marine protected areas (CBMPA) for each size category.

-Large effects between inside and outside CBMPAs were evident in each size category.

-Combined, these findings reinforce the stark difference in abundance across fish size categories between inside and outside the CBMPAs of villages with customary management and an urbanized center.

We now have yet another piece of evidence highlighting the need for marine protected areas to ensure healthy fish populations and coral reefs, as well as a need to conserve for the future health of a growing human population.  However, instilling good ocean management practices is not and an idea we can afford to treat with procrastination.  According to the authors, “There is a negative correlation between effective conservation and human population size (beyond a threshold of more than 1000 people) and between market integration and wealth, which suggests that as rural communities urbanize and monetize in Melanesia, their capacity to conserve resources weakens.”

And this negative correlation is perhaps the most interesting finding and something that sounds quite familiar.  As populations grow and become more economically viable they effectively lose their ecological self-control and ocean husbandry suffers. 

So is this humankind’s innate progression as we become less reliant on the natural course of the environment and aim to control it?  I have definitely seen this trend before…Have you?

ASWANI, S., & SABETIAN, A. (2009). Implications of Urbanization for Artisanal Parrotfish Fisheries in the Western Solomon Islands Conservation Biology DOI: 10.1111/j.1523-1739.2009.01377.x
Photo credits: Richard Ling

And what better way to start anew than with something to ease our appetites.  As I glance over the virtual menu I decide what the hell, “Waiter, I’ll take the tuna.”  I know I railed against overfishing, reported on the decreasing numbers of tuna, and have heard conservation organizations ask me to stay away from bluefin but no worries as the menu indicates nothing about item #13 being southern bluefin.  Oops, I guess he didn’t hear me, “WAITER, I’LL TAKE #13, THE CRITICALLY ENDANGERED TUNA…PLEASE.”

Yep, you heard it right that time.  A new study published Wednesday (Nov. 18) in PLoS has found that piece of tuna you just ordered and most likely eaten was potentially an endangered species.  And if I actually ate tuna sushi, that would be enough to make me sicker than ingesting a helping of week old sashimi leftovers.

Now that we know I’m safe from feelings of guilt and a potential bout of food poisoning, I’ll move on with the findings.  With a background in molecular biology, I love it when genetics rears its head in the world of conservation.  In this particular case, the researchers collected tuna samples from restaurants over a 7 month period in 2008 and, for the sake of brevity, used the obtained DNA to identify the species.  Here is a summary of their results:

-A piece of tuna sushi has the potential to be an endangered species, a fraud, or a health hazard. All three of these cases were uncovered in this study. Nineteen (out of 31) restaurant establishments were unable to clarify or misrepresented what species they sold.

-Twenty-two of 68 samples were sold as species that were contradicted by molecular identification, while six samples were sold as ‘‘tuna’’ or ‘‘red tuna.’’ 

-Five out of nine samples sold as a variant of ‘‘white tuna’’ were not albacore (T. alalunga), but escolar (Lepidocybium flavorunneum), a gempylid species banned for sale in Italy and Japan due to health concerns.

-Nineteen samples were northern bluefin tuna (T. thynnus) or the critically endangered southern bluefin tuna (T. maccoyii), though nine restaurants that sold these species did not state these species on their menus.

The high stakes, money making tuna market has effectively become a game of chance for the consumer. And when you can’t trust the restaurant, the menu, or the staff, perhaps it is better to err on the side of caution.  Just something to think about the next time you pick up your chop sticks.

Lowenstein, J., Amato, G., & Kolokotronis, S. (2009). The Real maccoyii: Identifying Tuna Sushi with DNA Barcodes – Contrasting Characteristic Attributes and Genetic Distances PLoS ONE, 4 (11) DOI: 10.1371/journal.pone.0007866

Sea turtle advocates in California and family shrimp fishers from Florida filed a federal lawsuit today against the U. S. State Department for violations of the Endangered Species Act (ESA) for allowing shrimp caught in ways that are deadly to sea turtles to be sold in the United States  The lawsuit filed by the Environmental Law Clinic at Stanford Law School (Palo Alto, CA) on behalf of Turtle Island Restoration Network (Forest Knolls, CA) and the Mayport Village Association (Mayport, FL) claims that the U. S. State Department has failed to properly evaluate and prevent harm to sea turtles from overseas shrimp fleets that sell shrimp to the United States under the ESA’s Turtle-Shrimp Law (Pub. L. 101-162 § 609). It was filed in the U. S. District Court, Northern District of California. See the complaint.

“This is not only a tragedy for sea turtles, which die by the tens of thousands in shrimp nets every year, but is unfair to the U.S. fishers who obey the law and must compete in the U.S. marketplace with shrimp imports,” said Todd Steiner, biologist and executive director of Turtle Island Restoration Network a non-profit organization dedicated to the conservation of sea turtles and their habitat.

“Our Mayport shrimpers are struggling to survive, while foreign fleets get a free pass on the law and flood the market with cheap shrimp,” said Al Millar, representing Mayport Village Civic Association and its small fleet of family shrimpers based in the historic village of Mayport, FL. See www.SaveMayportVillage.net. “We work hard to fish and protect sea turtles but don’t get a break from our own government.”

The lawsuit claims that the State Department has not properly enforced requirements for foreign shrimp vessels to use nets with Turtle Excluder Devices as U. S. fishers are required to do. The lawsuit asks that the foreign shrimp certification process be given additional environmental oversight and review. Recently, shrimp imports from Costa Rica were banned due to failure to protect sea turtles after environmentalists’ complaints, but 15 other nations were certified with little, if any, scrutiny.

“There is a simple, inexpensive, and elegant solution that allows sea turtles to escape drowning in shrimp nets, called a turtle excluder device or TED” said Deborah Sivas, Stanford Law professor, and director of the Environmental Law Clinic, who filed the lawsuit.  “If the State Department can create a reasonable certification program, we can save the lives of thousands of endangered sea turtles while allowing shrimp harvesting to continue.”

Americans consume over 500,000 tons of shrimp annually, and is the top fishery import of the United States, valued at over $3.9 billion last year, according to government figures. This includes trawl-caught wild shrimp and farmed shrimp (which does not capture sea turtles but is environmentally harmful due to pollution of fish ponds and land clearing). About 90 percent of shrimp eaten in the U. S. is imported. See latest U. S. shrimp import data.

Background:
The U. S. Turtle-Shrimp Law was challenged by nations at the World Trade Organization (WTO), claiming to be a violation of the “free-trade” agreement, leading to the famous “Battle of Seattle” protests in 1999 where thousands marched peacefully to protest weak environmental protections in the global trade treaty.  The U.S. Turtle-Shrimp Law was eventually found to comply with the WTO, but poor enforcement has allowed sea turtles around the world to drown in shrimp nets and slide toward extinction. (The movie Battle of Seattle starring Woody Harrelson that dramatized the protests was released in 2008). Read more .

On May 1, 2009, the Department of State certified, pursuant to Section 609 of Public Law 101-162 (”Section 609”), that 15 nations have adopted programs to reduce the incidental capture of sea turtles in their shrimp fisheries comparable to the program in effect in the United States. Belize, Colombia, Ecuador, El Salvador, Guatemala, Guyana, Honduras, Madagascar, Mexico, Nicaragua, Nigeria, Pakistan, Panama, Suriname, and Venezuela. The Department also certified that the fishing environments in 24 other countries and one economy, Hong Kong, do not pose a threat of the incidental taking of sea turtles protected under Section 609. Read more.