Notes on Overfishing and By-Kill

Overfishing is taking a deadly toll on the oceans.

Fish is commonly seen as a source of protein and B12. While I personally am a vegan, and therefore do not eat fish, the point to be made is that fish is in high demand. This, combined with the advancing technology in fishing, is starting to overwhelm reefs and other fishing sights.

Devastating numbers mentioned mentioned by the Fisheries and Aquaculture Department in Table 11 of a document reporting on shrimp overfishing shows that much more is being caught than shrimp. The fish that are not intended to be caught are referred to as by-catch. Thousands, and in some areas, millions of unintended fish are caught. Based on the data collected (tied to the data in Table 4), up to 98% of fish are simply discarded as by-kill. The lowest percent noted is 40%, yet even 40% is a problem.

The table concludes with an estimated average of 85% of by-catch being discarded as by-kill. I decided to add up the numbers myself to see if they were adding the percentages and finding the mean, or whether they were using the quantitative data in the table.

Using percentages and mean would be less reliable as fish populations would vary in different locations. If the actual amounts of fish were used, that would give an estimated percent of the overfishing problem around the globe.

I added the numbers and found that the locations combined had an estimated by-catch of 11,207,760. I then added the estimated discards. That number was 9,511,973 fish that were simply discarded as by-kill. Then, the division of 9,511,973 by the estimated by-catch (11,207,760) was a decimal of 0.84869527898. So, yes, the math used by the table was done with the more reliable and true method. 85% is a logical rounding of 84.8695%. I calculated the mean of the percentages. It was 84.33%. While this was close, it could not be rounded to 85%, but would round to 84%. So this helped me conclude that the source did indeed use the more reliable method.

The number of 85% is absolutely astounding, and this problem clearly must be addressed. While the document listed a variety of resources, I wanted to have more than one opinion on overfishing.

I used a search to see what universities and other scholarly articles noted on overfishing. Massachusetts Institute of Technology summarized several facts, quoted below from Mission 2015: Biodiversity.

  • In 2000, 72 percent of the world’s marine fish resources were either fully exploited or in decline according to the FAO (Duke)
  • The tonnage of fish caught in American fisheries from 1950 to 2006 has doubled to more than 4.3 million tons per year (NOAA 2007)
  • Roughly one-third of the world’s coral reef systems have been destroyed or highly degraded” (“Fishing and Aquaculture”)

I also have cited several other sources at the bottom of the post.

In conclusion, these sources agree—while overfishing numbers vary by area, it is a problem all over the world. The issue we face with the oceans is sometimes the immense mass they have. Because of this, problems we cause can spread around the globe. It is also so vast that much of what we do is careless. The ocean is a strong ecosystem, but the level of destruction we are causing will put the ecology out of balance. Since the ocean affects land ecosystems as well, what we put into the ocean is what we will get out of it.

Sources (Not Noted):
Battaglia, Nicole. Yale College 
Dartmouth Undergraduate Journal of Science 
The Pew Environment Group
Scripps Institution of Oceanography
Tao, Kenny. University of California

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