The reported harvest of fish from the sea amounts to over 90 million tons (fresh weight) each year. Another 50 million tons/year of seafood is produced in aquaculture. This is an enormous source of nutritious protein for our diet, amounting to the consumption of about 8 percent of the plant production in marine and freshwaters. About 87% of the catch is destined for food, and the rest used as fertilizer or bait to catch more desirable species. In coastal Maine, the availability of herring and mackerel as bait is a major determinant of the profit of lobstermen.
There is good indication that commercial fishing has depleted stocks in some regions, perhaps globally. Cod are essentially gone from the Gulf of Maine. But the degree of harvest, the cause of declines, and what might constitute a sustainable harvest are hotly contested. Unlike the land surface, we find it difficult to see what is happening under the ocean’s surface, and field experiments are tough to perform.
Good news is often scarce in the environmental realm, but I heard a piece of it recently regarding waste in the fishing industry. When large nets are used to capture desirable species, there is often “bycatch” of undesirable species that are often thrown back into the water. Unfortunately, most of the bycatch is known to die. For the harvest of fish from the seas, as much as 10 percent of the catch is bycatch, amounting to nearly 10 million tons per year. The good news is that the amount of bycatch has dropped from a peak close to 20 million tons in 1990, as reported by the Sea Around Us Project (www.seaaroundus.org)
While bycatch is declining due to better fishing practices and the retention of a wider variety of species that are deemed desirable, 10 million tons of wasted fish each year represents a lot of protein that could feed the human population. For the United States, less than half of the fish taken from the sea find their useful purpose as food. And, bycatch is not the only point of waste in the fishing industry. Recent work suggests that in the U.S., about half of the loss is wasted by consumers at the point of consumption. Thirteen to 16 percent of the fish lost are spoiled and discarded during distribution and marketing.
This level of waste in raw material would not be tolerated in most extractive industries. As the world’s population demands more protein and we recognize the dietary benefits of seafood, one can praise the lower level of bycatch recently reported and hope that we can do even better in the coming years.
I hate to see any fish die for no good reason.
References
Hastings, A., S. Gaines and C. Costello. 2017. Marine reserves solve an important bycatch problem in fisheries. Proceedings of the National Academy of Sciences 114: 8927-8934.
Love, D.C., J.P. Fry, M.C. Mulli and R.A. Neft. 2015. Wasted seafood in the United States; Quantifying loss from production in consumption and moving toward solutions. Global Environmental Change 35: 116-124.
Pauly, D. and V. Christensen. 1995. Primary production required to sustain global fisheries. Nature 374: 255-257
Pauly, D. and D. Zeller. 2016. Catch reconstructions reveal that global marine fisheries catches are higher than reported and declining. Nature Communications 7: doi: 10.1038/ncomms10244