No. 02–Casting for Shrimp

One of the perks of living in the lowcountry is the bounty of estuarine delicacies that surround us. They have been harvested and enjoyed as long as humans have walked these shores as witnessed to by the numerous pre-Columbian shell rings that dot the landscape.

We are now entering the season of the shrimp with this year’s spawn of “whities” beginning their slow migration to the sea and the ultimate culmination of their life cycle. A brief description of that life cycle follows. For more on all things shrimp, Amber Von Harten, Estuarium board member and Fisheries Specialist with the SC Sea Grant Consortium will lead an in-depth discussion on the history of the shrimp industry in SC to include the biology/life history of shrimp, environmental and fisheries management issues and the current economic crisis the industry is facing. The program will run from 5:30 to 7:30 on September 22nd at the downtown library at 311 Scott St. in Beaufort.

White shrimp spawn offshore in the spring. Eggs are released by the females and fertilized by chance as they descend through the sperm bearing water column. The offspring require full ocean salinity through their eleven larval stages and feed exclusively on plankton during this time. As post larva, 3 to 5mm long, they migrate from the ocean, up through the sounds and rivers and disperse throughout the upper reaches of creeks and marshes. The post larval and early juvenile shrimp feed primarily on detritus (decaying organic matter). As they grow their menu broadens to include worms and other invertebrates they find by probing the bottom sediments. They are not above scavenging and are known to attack and cannibalize defenseless molting fellows when the food supply does not meet demand.

By mid August the earliest spawned have reached a length of around three inches (good bait size) and begun moving from marsh creeks to the rivers where they will continue to grow. Historically a smattering of shrimp large enough for the table are being taken by mid September with the numbers increasing as the season continues. Shrimp will remain in the estuary and within reach of cast nets until falling water temperatures drive them into the deepest parts of the sounds or into near shore waters. There have been warm falls when they’ve hung around into November. The one thing that can cut a season short (as happened with last year tropical storms) is a sudden drop in salinity which will drive all shrimp, ready or not, into the ocean.

Shrimp that have managed to dodge both cast nets and predators over winter in the sounds and near shore waters before completing their lifecycle with the spring spawn followed by death.

Free roaming non-baited shrimp are, with a few exceptions due to site specific bottom topography, best taken on an outgoing tide usually half tide and down. Shrimp tend to partially burrow into the substrate (mud down) to avoid being swept backward on the incoming tide.

It takes some strength and stamina to repeatedly throw a cast net. Age and physical conditioning will determine the size of the net one will be able to use successfully. Most youngsters can handle a four foot net. Five or six foot nets are recommended for most adults. Seven and eight foot nets are available but require some heavy lifting unless the proper technique is mastered.

Cast nets can be deadly for small fish that get gill hung in them. You can literally cut them a break by having a pair of nail clippers in your pocket. Clipping a single strand of the net will release the creature relatively unscathed with minimal damage to a net that is easily repaired at a later time.

I don’t bait shrimp and wouldn’t anymore than I would shoot dove in a baited field or kill a deer over a saltlick block. To my mind shrimp on the table is an earned reward for those willing to learn their ways and work for them. It has been demonstrated that bating disrupts the natural movements of the species by enticing them to remain in an area longer than under normal conditions. Also, the biggest, strongest and most aggressive shrimp (desirable traits for a healthy gene pool) are concentrated on the bait balls and taken in disproportionate numbers.

If we are able to develop and maintain the perspective that the shrimp and other species we humans exploit for our pleasure and profit are a gift that is earned and not an entitlement, we will go a long way in assuring those resources will be available for future generations.