Fish, our Oceans, and our Health Part I

Last summer I had a argument conversation with a family member who is the typical gun-totten, freedom-lovin’ ‘Merican that has come to personify the American Right. We don’t always see eye-to-eye, as we are essentially polar opposites, but he is family and has always been there for me when I needed him (typically arriving 20 minutes late, but still… eventually he’s there). Basically the conversation was about our diets impact on the environment - he categorically and instantly argued that fishermen are catching record levels of fish, as an indication that the world’s oceans are perfectly healthy.

While I will probably never convince him otherwise, the evidence is pretty stark in the opposite direction.  So today I’d like to talk about the choices you have: plant-based versus meat-based diets, and how they influence the marine environment. These choices we make have a dramatic effect, and it’s helpful to understand the impacts some of our choices have on the global environment. Because this is such a long post, I've decided to break it into three parts. This is Part I which will focus on our current fishing practices. Part II will focus on Farmed Fish, and finally Part III will talk about some of the health concerns involved in eating fish.

The oceans are currently stressed from the amount of fishing and unfortunately, farmed fish are no better of a choice, and come with their own host of problems (discussed in Part II). Today our global fish population is experiencing something of a crisis - and the idea that our oceans are inexhaustible can no longer go unnoticed.

Beginning in the mid-20^th century, international efforts to increase the availability and affordability of protein-rich foods led to concerted government efforts to increase fishing capacity. Favorable policies and government subsides spawned a rapid rise of big industrial fishing operations.

If you look at this graph from a 2003 paper in Nature, they show, in stark terms, the decline of large predators in the ocean. These are the most popular fish to hunt and eat and as the chart demonstrates, there has been nearly a 90% decline in their overall populations. The graph can be read as an indicator of the concentration of fish remaining in the ocean. As Ivan Macfadyen recently wrote in his piece for the Herald, “The Ocean is broken.”

Another figure to help demonstrate this point is the total number of fish we bring in. According to international law, when fish are brought to port, fishermen are required to report their catches; and various organizations have kept track of these numbers since the 1960s. Since the ’90s, the total number of fish caught globally has leveled out. In 1989, 90 million metric tons of fish were taken from the ocean, representing a high-water mark. We have maxed out the ocean’s ability to produce since then.

According to the Food and Agriculture Organization of the United Nations (FAO), of the 600 marine fish stocks they monitor, 52% have been fully exploited and all of the 17 primary fishing stocks worldwide are either overexploited or on the verge of collapse. In 2003, a report announced that industrial fishing had reduced the number of large ocean fish to just 10% of their pre-industrial population. Examples of this collapse are the Grand Banks near Newfoundland and the Georges Banks of New England, both once considered the most productive fishing grounds on the planet, and both now nearly devoid of life.

While still hotly debated, many scientists are now supporting the theory that if current practices continue, all of the world’s fisheries could collapse by 2048.

Another indication of stress in the ocean is the average trophic level of fish caught throughout the globe. Harking back to high school biology class, a trophic level is the position in the food chain for a particular species. If a fish eats algae, it’s at the first tropic level. If it’s a carnivore that eats smaller fish, then it’s one level up and so it continues up to the largest predators in the oceans. Because the higher trophic-level fish, such as swordfish or tuna, bring in such large profits (some tuna sell for over $1 million dollars!) these are the preferred fish for fishermen. However, as their populations have declined, they’ve become more difficult to catch. The result is that fishermen have moved down the trophic-level. These fish have less value per pound but are currently more available than the higher trophic-level fish.

The impact of this is that we are now literally scraping the bottom of the ocean floors for whatever is left. Having to move down on the trophic-level is a dramatic indication that we have fished beyond sustainable levels.

Besides reducing the populations of the fish fisherman actually want to catch, we have also had a negative impact on less desirable species. Due to a process known as by-catch- fish unintentionally caught- many species have become endangered simply because we want to eat other fish. Sharks and more surprisingly seagulls have been large victims of this wasteful practice. Feel free to google image this. The images are too depressing for me to put up.

Finally, bottom trawling is, perhaps, the worst of all fishing practices. Basically, fisherman drag nets across the bottom of the ocean floor and gather everything in their wake. At the surface, they discard as much as 70% of what they pull up – all of it dead. It is a common practice used when shrimping. 

Unfortunately, the giant marlin that Santiago wrestled in Hemingway's "The Old Man and Sea" is becoming increasingly rare, and some day may only be found in the imagination of fiction. These issues about our environment and ecology need to be part of the public discourse. We need to face these hard truths if a true solution is to be found. 

Additional Reading:

http://www.mindbodygreen.com/0-11561/9-things-everyone-should-know-about-farmed-fish.html.

“Overfishing: Plenty of Fish in the Sea? Not Always.” National Geographic.

Ivan Macfadyen, “The Ocean is Broken.” http://www.theherald.com.au/story/1848433/the-ocean-is-broken/

Pauly, D., et all. “Towards sustainability in world fishers,” Nature 2002.

General Situation of World Fish Stocks, United Nations Food Agriculture Organization (FAO)

Harrington, J.R., et all., “Wasted Fishery Resources: Discarded By-Catch in the USA.” Fish and Fisheries 6.

Janicke Nordgreen, et all., “Thermonociception in fish: Effect of two different doses of morphine on thermal threshold and post-test behavior in goldfish.”Elsevier

Rosamond L. Naylor, et all., “Effect of Aquaculture on World Fish Supplies,” Nature Vol. 405, June, 2000.

Oppenlander, Richard. Food Choice and Sustainability: Why Buying Local, Eating Less Meat, and Taking Baby Steps Won’t Work. New York, Langdon Street Press, 2013. 

As always the information presented in this blog is for educational purposes only. It should not be considered as specific medical, nutritional, lifestyle, or other health-related advice.