Maine’s wild soft-shell clams are under threat, but Dr. Beal is fighting back.

photo by VS user mymilkshake1

Last spring we got to help study predation of soft-shell clams with Dr. Brian Beal from the Downeast Institute. There are many predators of soft-shell clams but green crabs are the major threat. Soft-shell clams are one of Maine’s most valuable fisheries, second to lobsters and elvers. Today, just finding clams has become a challenge.

These results suggest that predation on small clams (both cultured and wild) is intense, and can easily explain the recent decline in wild clam populations in many intertidal areas in southern
Excerpt from Webhannet and Fore River Studies (2014) report, Brian Beal - Downeast Institute

Photo by Sarah Kearsley
Photo by Christine Voyer

Dr. Beal studied how tidal height and exclusion of predators impacts both wild and cultured clams. To do this, plots of protected and unprotected treatments were set up in the lower and upper intertidal zones. Each of these plots had flower pots with several different types of screening and some with no screening. The pots were filled with the surrounding sediment and 10 hatchery seed clams. The hatchery clams are ‘self marking’ in their growth rings, so Dr. Beal could observe how much they had grown in the flower pot.

The experiments were set up in the Fore river in Portland and in the Webhannet river in Wells in the spring and then dug up in October. There were several interesting findings from his study, but the most striking was the impact on wild clams.

In the protected pots, not only did the hatchery clams survive but sometimes hundreds of wild clams per pot did as well. These baby wild clams settled in the protected flower pots after they were placed. Almost no clams survived in the unprotected samples.

The results paint a stark picture: soft-shell clams face immense and deadly predation pressure. The incredible part is that there is still a “rain” of wild clam seedlings out there, all they need is a safe place to grow up. Dr. Beal thinks that small scale predator exclusion is workable and would be effective. Now that’s a story that might cheer up Maine’s beleaguered clamming industry.

We highly encourage you to check out the full report here.