Down East Salmon Study Provides Experience for UMaine Undergraduate
Contact: Nick Houtman, 207-581-3777
ORONO– Few migrating juvenile Atlantic salmon make it out of Down East Maine’s Shorey Brook these days without getting noticed. University of Maine researchers are placing tiny transmitters inside each fish and picking up the signals with antennae downstream. Before the young salmon begin their migration to the sea, researchers are also analyzing their diets and growth rates. For Chris Holbrook, a senior in zoology from Norway, Maine, the chance to participate in this research is preparing him for a career in fisheries biology and conservation.
As part of a science team in the lab of UMaine biologist Michael Kinnison, Holbrook has been helping to capture stocked Atlantic salmon and other native fishes in Shorey Brook, a tributary of the Narraguagus River. His particular specialty is collecting information about what the fish are eating to determine how successful stocked salmon are in competing for food. Funded by a grant from the Maine Atlantic Salmon Commission, researchers aim to understand the factors affecting salmon survival in Down East rivers.
“My goal is to find information about the diets of the salmon, which were stocked as tiny fry, and the fish that were already there. Is the food source limited? No one really knows. If it is, overstocking juvenile salmon may not be the best thing to do,” Holbrook says.
After graduating from Oxford Hills High School, the young landlocked salmon and brook trout fisherman attended Northland College in Wisconsin and worked on a Chinook salmon project for the U.S. Geological Survey on the West Coast. He transferred to UMaine in the fall of 2001. With salmon research experience already under his belt, he also got a part time job with the National Marine Fisheries Service (NMFS) in Orono working on Atlantic salmon. The federal government listed sea-run Atlantic salmon in eight Maine rivers as endangered in 2000.
To see what sorts of fish food are available, Holbrook sets up drift nets that collect insects living in the pool and riffle stream habitats. With Ph.D. student Michael Bailey and other researchers, he also assists an electrofishing effort in which temporarily stunned fish are captured and fitted with transmitter tags. The researchers take a small piece of fin tissue for genetic analysis, clip a scale sample for age determination, and record the weight and length of each fish.
Holbrook collects stomach contents using a harmless technique known as “gastric flushing” and stores his samples in small bottles, one for each fish. Back in the lab, by studying what salmon, brook trout, black nosed dace and other fish are eating, Holbrook is contributing to a better understanding of how successfully salmon are competing for food with other native fishes.
The prevailing hypothesis, he explains, is that there is lots of overlap in what different species eat. Moreover, young fish tend to be opportunistic eaters. For example, they do not normally eat slugs, but during one sampling run after a particularly heavy rain last fall, says Holbrook, researchers found that the fish were eating slugs that had apparently washed into the stream.
Holbrook knows that major questions about how stocked salmon fare after being placed in a river will not be fully answered before he graduates in December, 2004. Nevertheless, he intends to pursue them further in graduate school, and hopes his efforts will contribute to salmon restoration. River restoration projects, such as the one that has been proposed for the Penobscot River, will provide researchers with exciting opportunities to learn about how fish are affected by changes in the streams they inhabit.
Support for Holbrook’s research has come from the NMFS; Sigma Xi, the Scientific Research Society; and the UMaine Dept. of Biological Sciences.