Statement of Intent

This first page should give a general sense of the impact the issues humans have created through our own fishing practices. Each of the following briefs gives an overview of a separate sources of evidence to the collapse of fisheries worldwide and some of the factors that are overlooked on this subject. This site will walk through different policies and management plans that have been used and finish with some personal perspectives on what management is appropriate for future fisheries.

Critical Depletion of Fish

There has been an overwhelming decline in the number of fish caught since the beginning of highly industrialized fishing. This decrease can be understood as an overall depletion of fish in the seas. A figure from a comprehensive study below shows this dramatic drop and how this drop is exacerbated within the temperate regions compared to the tropical regions.

Myers, R. A., & Worm, B. (January 01, 2003). Rapid worldwide depletion of predatory fish communities. Nature,423, 6937, 280-3.


Not only are these fisheries appear to be under a steep decline, but this decline has ended with fish stocks at only 10% of the original amount!

Genetic Impacts on Size

Data shows that fisheries can have direct affects on the genetics of fish populations. In the late 1980s and early 1990s overfishing of the Northern and Atlantic Cod resulted in a shift to smaller sizes and earlier maturation. The graph below shows these changes for three distinct populations of cod over time. This helps give a visual representation of how overfishing can cause fish to start to adapt, breeding earlier before they get caught and staying small because it is the large fish that are most desired by fishermen. However, this shows the significance of letting our oceans be fished unchecked. Without caution we might get rid of the type of fish we like the most, not just because they were caught, but because the fish adapt to avoid our selective pressures.

Source: Maturation trends indicative of rapid evolution preceded the collapse of northern cod. Esben M. Olsen1, Mikko Heino, George R. Lilly, M. Joanne

Another study was done to show average changes in fish sizes over a series of generations. They found that large harvested lines declined significantly in mean weight of the fish caught and total weight of harvest compared to a random harvested line. Interestingly these mean weights actually increased for the small harvested lines, which shows the huge impact of size-selective fishing on a population.

Source: Conover, D. O., & Munch, S. B. (January 01, 2002). Sustaining fisheries yields over evolutionary time scales. Science (new York, N.y.), 297, 5578, 94-6.

Fishery Management: Where are we at?

Fishery management has certainly not become easier over the years. This graphic below summarizes the findings from a scientific study looking at how effective fishery management is in Economic Exclusive Zones (EEZs), those areas 200 nautical miles off the cost of a country in which that nation is given exclusive rights to fishing within those waters.

Their analysis included an assessment of scientific robustness (understanding the best sustainable approaches for their fisheries), policy-making transparency (cooperation between groups and government to make the policies), implementation capability, fishing capacity, reliance on subsidies and access to foreign fishing. The cumulative representation of their findings are summarized below and it becomes clear that there is no where on the map that has highly effective management of their fisheries. The largest difference that they found was in transparency of policies; having poor communication about making decisions on management was more detrimental than even having the solid science, because these voices could be present but not heard if politics drive decisions. From this we can begin to see that policy is much more than just understanding how fish interact with their ecosystem. These policies will be discussed further under the tab "Policies."

Mora, C., Myers, R. A., Coll, M., Libralato, S., Pitcher, T. J., Sumaila, R. U., Zeller, D., ... Worm, B. (June 01, 2009). Management Effectiveness of the World's Marine Fisheries. Plos Biology, 7, 6.