Recently, the New York Times Green Blog described how two major Southern California fisheries (kelp and barred sand bass) had collapsed “right under the noses of management agencies.”
The management and oversight of these fish stocks had not changed since 1959. This news is perhaps not surprising as there are more examples of marine species collapses off our coastline than possible to list in this blog post.
Though the media tends to focus on the effects of pollution, climate change, or overfishing, outdated systems of management are actually the main cause of the collapse in many cases.
The ups and downs of abalone stocks off of the coast of Southern California provide an example of how poor fishery management resulted in the collapse of a population. Only a few years after the Palos Verdes Peninsula abalone stocks re-opened for commercial fishing in 1943, the stocks began to decline again, as more than 9.3 million pink abalone were collected during the peak decade of the fishery (Taniguchi 2013).
These waters are home to one of the largest kelp forests in the Pacific, and this giant kelp (Macrocystis Pyrifera) is the main food source for abalone, sea urchins, and many other fish and marine mammals. Because of a spike in population growth after World War II, a greater amount of sewage was discharged into the water, leading to the deterioration of kelp forests. This pollution, combined with a warmer water temperature because of the 1957 El Niño event, rendered the kelp forests practically extinct, which meant to loss of abalones’ main food source.
Therefore, because of a lack of food, the abalone either did not reproduce or had badly weakened shells and stunted growth. Even after the kelp gradually grew back and abalone populations increased because of stricter regulations, poaching became a huge problem. Because abalones are found in predictable, accessible locations, and because they have a high unit value, the value of individual animals outweighed any risks or penalties for poaching. Enforcement of the laws was minimal because of California’s small environmental budget—there were only five wardens responsible for monitoring “hunting, fishing, exotic animals, [and] pollution events” for the entire inland Los Angeles County (Tegner 1993).
Since 1977, this fishery has been closed to sport and commercial take of abalones along parts of the California coastline. Yet this closure has not led to abalone population recovery because the off-limit areas were not located in areas with existing abalone stocks, so recolonization was not possible. Neither was poaching was not heavily monitored (Tegner 1993). Recent research has also found that opening up abalone reserves to fishing can result in immediate and drastic declines in abalone density, size, and reproductive capacity (Rogers-Bennett 2013). Perhaps only with time and new management strategies will abalone populations have a chance to recover.
The history of the California sardine fishery is another example of failed regulations and drastic overfishing.
via Scientific American – Katie Lee
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