marine biology

The Dragon Behind the Glass by Emily Voigt

picture of The Dragon Behind the Glass by Emily Voigt on top of a closed mac laptop. The bright red asian arowana on the cover stands out in stark contrast to the black background of the book coverAt first glance, The Dragon Behind the Glass by Emily Voigt seems like it will be a true crime style book about a highly coveted, ornamental trophy fish. The Asian arowana, or the “dragon fish”, is a modern phenomenon in the world of aquarium enthusiasts, prized for its rarity and dazzling colors (red, gold, and green). Baby Asian arowana sell for a few thousand dollars, while prime adult specimens can sell for upwards of $150,000. On the surface, Voigt presents the history and current events surrounding this fish, focusing on those that depict the obsession arowana lovers as well as the miasma of half-truths and danger that surrounds the Asian arowana. Stories of fish farmers or sellers being robbed at gunpoint multiple times or of judges at expos refusing to be responsible for arowana judging for fear of their safety/life are the norm. But, woven throughout these fantastical tales is an important discussion about our effect on the environment and animals — how much are we to blame and what is the best course of action to correct these wrong-doings?

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Baleen Whale Cortisol Levels Reveal a Physiological Response to 20th Century Whaling

Today I learned: whaling in the 20th century indirectly stressed out many different species of whales. A group of scientists looked at the earplugs of three different types of baleen whales: fin, humpback, and blue. A whale earplug is a collection of ear wax that has alternating lines that tell the age of a whale (like tree rings do) and store both endogenous (i.e. hormones) or exogenous (i.e. pollutants) chemicals. Because of this, they could measure the amount of cortisol, a stress hormone, in each whale during many different years. They found that when whaling numbers peaked, there was also a peak in the average cortisol levels. Interestingly, when whaling decreased during World War II, they still saw slightly higher cortisol levels, which suggests that wartime noises (i.e. submarines, bombing/explosions, planes, etc.) also increased the stress in the whales. The sharp drop in cortisol levels in the 1970s was connected to the start of the Marine Mammal Protection Act that put a moratorium on whaling. However, cortisol levels have been slowing increasing since then, indicating that other stressors are present (i.e. increased sea temperatures, over-fishing, and noise).

Graph showing that when whaling numbers peak, there is a peak in cortisol levels

The graph shows that from 1900-2000, when whaling numbers (blue) increased, there was also an increase in cortisol levels (black). Highlighted in grey is a period corresponding to WWII where the whaling numbers were low, but cortisol was still high. Also shown is a red line to indicate when the Marine Mammal Protection Act went into effect in 1972 to emphasize the sharp drop in cortisol levels that followed.

Reference: Trumble, Stephen J., et al. “Baleen Whale Cortisol Levels Reveal a Physiological Response to 20th Century Whaling.” Nature Communications, vol. 9, no. 1, 2018, doi:10.1038/s41467-018-07044-w.


Modern Slavery and the Race to Fish

Today I learned: about 32% of wild-caught fish that is eventually sold in the US is illegally caught. Because of how fish are caught, and then distributed, it is really hard to track which shipments come from ships/fishery sectors that abuse their labor force. Additionally, labor accounts for 30–50% of fishing costs and many fishing sectors are seeing falling profit returns, prompting many countries to cut costs and resort to unethical conditions to make a profit. A group of researchers from Canada and Australia looked at a few different metrics to try and identify which countries were more likely to have poor worker conditions. The authors found that a country’s Global Slavery Index (GSI), the percent of unreported fish caught, the value of the fish caught, and the amount of distant-water fishing best predicted the countries that had modern slavery in the fishing industry. While an obvious step to reduce the unethical conditions includes more oversight on the ships themselves, more research has to be done to understand how the current problems affect fisheries policy.

Diagram showing that the more that the US, Western European, and Scandinavian countries import fish from high slavery-risk countries, the more likely that the domestic supply contains illegally caught fish

River plots showing that when the US (left) and Western European and Scandinavian countries (right) import fish from high slavery risk countries (yellow, orange, and red), the domestic supply contains fish caught under unethical conditions. (Figure adapted from Tickler et al.)

Reference: Tickler, David, et al. “Modern Slavery and the Race to Fish.” Nature Communications, vol. 9, no. 1, 2018, doi:10.1038/s41467-018-07118-9.

War of the Whales by Joshua Horwitz

An unusually large whale stranding event in the Bahamas on March 15, 2000, set into motion a clash between environmental activists and the US Navy. War of the Whales, part detective and part history novel, by Joshua Horwitz covers every nuance of this battle, while also providing some really cool marine animals facts throughout. As someone who toyed with becoming a marine biologist, until realizing that a fear of open water and studying marine animals don’t really mix, this book was right up my alley. Right off the bat, you get to learn that beaked whales are the only predator that regularly dive one mile deep; with one dive even being recorded at two miles deep for just over two hours. Even if you don’t have a lot of background knowledge on these topics, this book is super easy to read, largely due to Horwitz’s writing style. War of the Whales skillfully avoids being a dry listing of facts thanks to its well-written and compelling narrative that spans across a decade or so of back-and-forth between activists and the US Navy, along with brief ‘flashbacks’ to give the historical context that led up to the current events. So, for anyone who is even mildly interested in the ocean or the interplay between ocean conservation and military policy/practices, this book a great choice.

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