Meager in shallow water: protected but vulnerable | Forum


A kayaker stops in a narrow, shallow passage to capture an image of marsh hibiscus.

Kayaking is such a simple and therapeutic pleasure. Shallow water abounds in the Chesapeake Bay, and car roof racks are testament to its popularity. In tidal creeks, rivers and protected bays, passive slides bring the envelopment of nature. The arms work against the wind and the tide. Immersion and effort eliminate worries in the wake of the kayak.

These meager waters are also therapeutic for the bay itself. These are its most functional habitats: nurseries for fish, beds for reefs and underwater grasses, and incubators for forage species that support oysters, crabs, fish and wildlife.

It is therefore no wonder that these shallow waters receive the highest protections from the government. The Chesapeake Bay Program applies its strictest water quality standards to two habitat categories: narrow tidal waters, including coastal waters less than 2 meters deep, and spawning areas. migratory and nursery grounds, which are mostly shallow upper estuarine waters where

bass, perch, shad and other fish spawn.

Twenty years ago, I worked with a team to develop these protectors, and they held up well. Yet, as a result of this effort, there remain greater perils to skinny waters: climate change, invasive species, and development in coastal rural counties.

Along the banks of the Potomac River, we summer paddlers share skinny waters with countless juvenile 2-inch striped bass. Their numbers vary greatly from year to year, depending on the survival of eggs and larvae in the spring. Upstream of the Nice bridge, the large females lay billions of eggs according to the spring seasons. Early mortality is abrupt and bass have adapted by reproducing repeatedly over long lifespans. A 30-year-old striped bass has more than 20 batting times to replace himself.

Enter climate change. Spring is now a less predictable transition between seasons, narrowing the window of favorable conditions. Combined with recent overfishing and disease, most females only get batted once or twice.

Protecting the nursery function of lean waters from climate change therefore has more to do with managing the fishery ― maintaining older spawners ― than with improving water quality.

Enter the blue catfish. From 1974 to 1985, Virginia introduced hundreds of thousands of them to the freshwater rivers of Lower Bay. But the fish had an unexpected predilection for brackish water, and within 20 years they had exploded in abundance, invading all major tributaries.

In a 2013 survey of a 7-mile stretch of the James River, Dr. Mary Fabrizio and her team at the Virginia Institute of Marine Science estimated the number of blue catfish at 1.6 million, more than all commercial harvesting of striped bass from the bay. As the top predator, they take a big bite out of the juveniles that feed our native fish. There’s no obvious solution, but promoting harvests of blue catfish would help young striped bass and other native fish escape predation.

Kayaking near Great Mills on the St. Mary’s River requires a lot of maneuvering between obstacles: submerged snags and overhanging trees and vegetation.

This weaving and dodging, a great sport in kayaking, is the result of coastal zone protections: Homeowners and small businesses along the river have helped conserve and even enhance riparian vegetation. These areas of trees, swamps, marshes, and undergrowth provide habitat and protect meager water from runoff.

Enter coastal development. Strategic planning for Lexington Park in St. Mary’s County focuses a corridor of high-density commerce, industry and housing along MD Route 235 away from coastal areas.

Yet the county is a narrow peninsula, so the corridor straddles the headwaters of the St. Mary’s River within 1 to 3 miles of tidal waters. Impermeable surfaces exceed 10%, the threshold above which the transport of sediments, nutrients and other pollutants harms living resources.

In coastal rural counties and cities, these impervious thorns of development continue to grow, paralleling and crossing thin waters – for example, along State Routes 2, 4, and 5 in southern Maryland; from Virginia

I-64 and State Routes 3 and 17; and US Routes 50 and 13 from the Delmarva Peninsula.

The EPA’s strict protections for lean waters, while remarkable in their accomplishments, have not kept pace with the threats.

The most important battle for lean water conservation is not in improving agricultural practices in Pennsylvania, nor in restoring oxygen to the bay’s deepest waters. It is close to the lean waters themselves: actions that give living resources a fighting chance against climate change and other assaults. Critical actions include reversing overfishing, bringing blue catfish under control, and extending coastal zone protections to these backbones of coastal rural development.

On a recent paddle in the brackish part of the St. Mary’s River, I got out of my kayak and picked a large live oyster from the sandy bottom. The water was crystal clear except for the dense areas of sea grass. There is a lot to savor and store here.

Dave Secor is a fisheries and environmental scientist at the University of Maryland Environmental Science Center, Chesapeake Biological Laboratory.

Opinions expressed by opinion columnists are not necessarily those of the Bay Journal.


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