The Wake County (North Carolina) Public School System’s sixth grade science classes are reading World Without Fish by Mark Kurlansky. Published in 2011, the author states that on the current trend most fish we know of could be gone in 50 years! Even worse, since all life is interconnected, including on land and in oceans, loss of fish populations will affect other wildlife like birds as well as threaten the food web and human existence.
Environmental stresses such as climate change and pollution and fishing fleets using drag nets to meet consumer demand are leading causes for species depletions and extinctions. Biodiversity is the key to success for all life which would be threatened if fish species decline. For example, overfishing bluefin tuna would harm dolphins and cause other species like jellyfish to expand. Seabirds that eat fish would also die out causing problems on land. Reptiles would not have food that is discarded by sea birds.
It’s interesting to read how many scientists in the late 1800’s thought fish populations could not diminish due to abundant egg production and fisherman would never intentionally impact fish populations. They misused Darwin’s “survival of the fittest” by not considering new inventions like the steam engine and monofilament plastic nets that allowed for deeper bottom fishing. People mistakenly thought fish in the deep oceans were as abundant as along coastal waters.
Humpback whales and herring eat krill - shrimp-like creatures which eat microscopic phytoplankton. White meat fish include cod, haddock, flounder, and halibut can swim near the bottom of the ocean and swim to the surface to eat smaller fish and shell fish. These fish are prized in commercial markets. Middle ocean depth fish include sardines, anchovies, herring, mackerel, and tuna have darker flesh and contain oily fluids.
Mr. Kurlansky aptly points out the sad story of the Orange Roughy that only 50 years ago became too popular and within a decade diminished by 90% in Australia due to a lack of scientific understanding. These red fish are found at depths of 5000 feet and turn orange when they die. They can live for 150 years but do not begin reproducing until age 20 so catching juvenile fish harmed the entire population.
Fish farms may not be the answer for sustainable fishing due to related problems. Ships the size of factories net and grind up fish for feeding farmed fish. The book shares that four pounds of fish meal are needed for one pound of farmed salmon. Farmed fish confined to small overcrowded areas develop weaker muscle tissue as well as increase water pollution.
The best solutions for sustainable fishing are for consumers to buy fish labeled as “certified sustainable seafood.” Higher prices to fisherman are going for line-caught fish like white albacore tuna and we can avoid buying other fish higher on the food chain such as bluefin tuna and shark. Lower food chain fish are more abundant and sustainable including sardines, anchovies, and herring. Other suggested actions include becoming active in environmental groups and promoting international relations to change consumer demand.