Sea Scallop Predation Experiment, Shinnecock Bay
Images and text courtesy of Chris Paparo, Southampton Marine Science Center Manager, and PhD student Stephen Heck
Seasonal abundances of large fish (striped bass, black sea bass, porgy, tautog, oyster toadfish) have changed over the past several decades. These changes have been largely attributed to fishing pressure and a changing climate. Many of these large fish are major predators of crustaceans (blue crabs, green grabs, mud crabs) that are in turn some of the dominant predators of bay scallops. We hypothesize that a higher abundance of large fish predators may not only reduce the abundance of crustaceans since the fish directly consume them, but also might reduce the rate at which they the crustaceans are feeding since more large fish means an increased risk of being eaten if they are out searching for prey. Therefore, we suspect that higher abundances of these large fish predators may indirectly benefit the survival of bay scallops, since crustaceans are not only less abundant but also feeding less frequently.
We looked into this in seagrass meadows in Shinnecock Bay. In the fall of 2016, we selected seagrass patches of approximately the same size. We placed an enclosure in the center of each patch. Half of the patches had fish in the enclosure and half were empty. In order to mimic how juvenile bay scallops normally cling to seagrass to escape from predators, we attached small plastic tabs to individual scallops that were pushed through the center of eelgrass blades at standardized distanced from the enclosures.
The experiment was run overnight and the number of scallops recovered alive was quantified. Preliminary data suggests that the presence of some of these fish predators increases the survival rates of bay scallops, presumably by deterring crustaceans from foraging as frequently on bay scallops in the presence of these larger fish, although more work remains to be done.