Chapter 16. Chapter 16: Fisheries and Aquaculture
What is aquaculture and how might it ease the strain on at-risk...?
Guiding Question 16.5
What is aquaculture, and how might it ease the strain on at-risk fisheries? What trade-offs does aquaculture involve?
Why You Should Care
Aquaculture is for aquatic species what agriculture is for farmland and terrestrial species—a human-managed ecosystem for raising food. The fish or invertebrate species (like shrimp or molluscs) are protected from predators and then harvested when they reach an adult size.
Aquaculture mimics marine ecosystems and uses them for nutrients and waste recycling. Aquaculture is becoming more common as costs are decreasing with larger aquaculture "farms." But costs are still high enough that only the most valuable species are raised, and these tend to be higher trophic level species. Those species require more food and nutrients, which are typically coming from other wild-caught fish or bycatch. These higher TL species also release larger amounts of waste that the marine ecosystem must recycle.
If aquaculture is to become common enough to replace fish protein from wild-caught fish and give fisheries time to recover, then it must become more sustainable. Technology and research are finding solutions, but for that to happen, consumers must embrace those changes and choose sustainably harvested or grown fish.
Test Your Vocabulary
Fill in the blanks below.
A is a fishery that ensures that fish stocks are maintained at healthy levels, the ecosystem is fully functional, and fishing activity does not threaten biological diversity.
Fish-farming, the rearing of aquatic species in tanks, ponds, or ocean-net pens, is called .
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Aquaculture differs from fishing because:
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What advantages does RAS aquaculture have over ocean-bound aquaculture?
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Short-Answer Questions
Tuna refers to a group of 50 related marine fish species that are commercially very important. Tuna are large, high trophic level fish that range in size from 20 to 1200 pounds. They are also very fast swimmers, which helps them to be efficient predators of smaller fish. This speed also forces fisherman to use large nets to catch them in any great number.
Tuna catch tripled between 1940 and 1970 (to 1 million tons) with the rise in usage of seine nets (wide nets that are used to fish out specific depths of the ocean). Between 1990 and 2010, the catch rose again to almost 4 million tons globally. This rise follows the use of large industrial fishing vessels that range across whole oceans, following schools of tuna.
1. What political options are there to protect ocean areas that are outside of national boundaries? What could we do to police those areas effectively?
2. Today, seven of the ten most popular tuna species are considered threatened across large expanses of the Atlantic, Indian, and Pacific Oceans. One species (the skipjack tuna) is under-fished and is in no danger. What are the advantages and disadvantages of switching tuna fishing to skipjack tuna only?
3. Tuna schools follow dolphins because dolphins discourage sharks preying upon the tuna. Dolphins are often found in the bycatch of tuna nets, and in the 1990s, this led to efforts to ecolabel “dolphin-safe” tuna. Since there is no international authority to verify this label, the World Trade Organization banned the label in 2011.
a. Should there be international authority to verify tuna fishing outside of EEZs?
b. Despite international agreements to limit tuna fishing in mid-ocean areas (outside of any EEZs), fishermen from Australia and New Zealand have been overfishing (and under-reporting) tuna catches. How could those fishermen violating quotas be policed and punished?
2. The advantages of switching to skipjack are that they still harvest tuna but give some time to other species to increase their numbers and recover. Disadvantages center around the effect on the skipjack of this focus (would it reduce the skipjack to threatened levels?) and questions about why the skipjack is not already a focus (is it not as tasty?).
3a. Tuna is so valuable that it probably should have an international body made up of nations that fish tuna to protect its numbers. If tuna numbers were to crash the way that cod did, it would have widespread economic impacts.
3b. Overfishing would be illegal only if there were agreed-upon quotas and legal authority given to not only observe, but also punish, those who harvested too much. This would involve a new international cooperation that doesn’t really exist for marine species and countries agreeing to be bound by the new laws.
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