Increased nutrient runoff spells trouble for coastal fisheries, nurseries

By on June 26, 2015

For anglers with access to a beach, coastal saltwater fishing offers a unique experience with its own benefits and challenges.

Man-made structures such as pier pilings, seawalls and bulkheads are readily found on just about any beach, and are great spots to cast a line. Fish congregate around these structures to snack on barnacles and other invertebrates, and to exploit their lucrative hiding spots.

There are literally tons of fish to catch in the surf. Nearly 90 percent of global fishery catches — both recreational and commercial — come from the sea, and the majority of those fisheries are located along the coast, where nutrients from land runoff help make conditions well-suited to rearing large populations of fish.

Unfortunately, many coastal fisheries may soon find that too much of a good thing is — well, you know how it goes.

A recent study from the University of California, Santa Cruz, found that the global expansion of human populations along coastlines is driving nutrient runoff up. As a result, algae blooms are occurring more frequently, consuming oxygen in the water and causing declines in fish diversity and overall health in coastal nurseries and fisheries.

One particularly massive algae bloom is already wreaking havoc along the West Coast, shutting down commercial and recreational fisheries as far north as Homer, Alaska and all the way down to Monterey Bay, reported.


An aquaculture pen used for rearing fish in a marine fishery off the coast of Maine. (Credit: NOAA/National Ocean Service)

The toxic bloom is the biggest seen on the West Coast since 1988, and is stumping scientists with its unusual timing. Most major blooms occur in the fall, but some researchers suggest that an abnormally warm spring may have primed conditions for algae growth.

Based on 40 years of data, the UCSC study says these sorts of events could become more and more common as global seas warm. But the impact of climate change on El Niño — a major factor impacting coastal nutrient levels and temperatures — is not well understood, making it hard to predict just what to expect.

To ensure that our kids (and theirs) have access to healthy, productive fisheries, we’ll have to examine how we use land-based resources and improve our agricultural practices.

“We need to have better dialog between land managers and ocean managers — between farmers and fishermen — to ensure that land use practices are being improved to reduce adverse effects of nutrients on coastal and marine ecosystems,” said the study’s coauthor Mary Gleason in a UCSC press release.

So make use of these bountiful angling spots while you can, but be sure to practice sustainable fishing. While most of us are fishing for fun, millions of people around the world rely on coastal fisheries for a living. As the inherent stability of marine habitats decreases, a greater responsibility rests on every individual angler to preserve these vital resources.


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