The Real Threat to Coastal Fishing

ke gill-netters, purse seiners, and those interest-stacked policy boards seem like minor nuisances.

This fight isn’t about who gets which share of the fish – it’s about having any fish left.

At current rates of sea level rise, many coastal estuaries will be flooded before the end of this century. When that happens, both recreational and commercial coastal fishing will collapse.

That’s because 80 percent of the recreational marine catch is estuary-dependent.

Figures for the commercial side run to 70 percent nationally, 90 percent in the Gulf.

Estuaries are not just the daily habitat for fish like speckled trout, flounder and drum, they are also the farmland that produces groceries for a vast array of other species – including many that spend their entire lives in the open oceans.

Biologists say during previous periods of sea level rise, estuaries adapted by migrating inland. But coastal development has now blocked that adaptation. In the U.S. alone, 40 percent of the population now lives along the coast. Low lying coastal plains that once could convert to new marshes are now layered in concrete.

This threat isn’t something dreamed up by computer models. It’s an unfolding disaster that’s been measured daily for decades. The history can be viewed on the NOAA site Sea Level Trends.
Sealeveltrends

Screenshot from NOAA Sea Level Trends

These are graphs of the high tide level recorded each day at tide stations along our coasts (and around the world) for many years. Plotted on a graph, they display trends. And as the arrows show, the trends are rising. (The exceptions north of the U.S. are in areas where water stored as ice has melted, leading to a rebound effect – like a memory foam mattress after you rise in the morning.)

The seas are rising because water expands while it is heated, and because water once stored on land as ice is melting and pouring into the oceans, adding to their volumes.

The rises on the Louisiana coast and east Texas coast are four times larger because those areas are also subsiding while the sea is rising, a process called relative sea level rise.

These trends are bad news on their own because the steady rise will mean the slow death of a many estuaries. But the news gets much worse in the last few decades of the century, as sea level accelerates due to accumulated warming. In many areas now, the mid-range projections of sea-level rise are close to three feet.

In Mississippi River delta – the most productive coastal estuary in the lower 48 – the rate will be between 3.5 and 5 feet.

The impacts of climate change on coastal sport fishing don’t stop there. Pollution associated with global warming is causing acidification of oceans, killing reef communities so important to a wide range of species, as well as expanding the dead zones (areas of low dissolved oxygen) already plaguing coastal areas.

All of these impacts have been known for some time, but have gained little attention from the marine sport fishing industry. Instead, its major voices have been aimed at the old fight with the commercial section over who gets what share of the fish.

Sportsmen’s conservation groups have been partners in that fight, for good reason. But it’s time for them to begin focusing on the real threat to the future for the resources and our traditions.

This fight isn’t about who gets the fish. It’s about how many fish will be left, period.

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