Science meets stripers in Bay State
Biologist studies coastal rivers
February 13. 2005 8:00AM Article written by
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Imagine using a fishing rod for scientific research. Fly and spinning rods were the tools of choice when Kristen Ferry studied striped bass on 13 coastal rivers in Massachusetts when she was working on her masters degree at the University of Massachusetts-Amherst.
The biologist for the Massachusetts Division of Marine Fisheries described her research project during the recent Rockingham Hunting and Fishing Expo in Salem.
Ideally, fisheries management should be based on the best available science. Understanding the science of striped bass habitat can also be a tremendous help to an angler. At the most basic level, it helps to know what a fish wants to eat before putting a fly or lure in front of its nose in the hope that it will strike.
We have a long way to go in studying the in-shore habitat. Ferry described her initial efforts as examining only the tip of the iceberg.
Putting things in perspective, Ferry recalled the striper crash of the 1980s. She attributed it to over-fishing and poor water quality in the Chesapeake Bay. Very few juveniles joined the adult population.
In what she described as a rarity in fisheries restoration, Ferry noted that the population had recovered by 1995. Although the population sees expected fluctuations, "We are managing the fishery now at that top end. We are not down in the 1982-82 range where the stock was very depressed. It's very good news for the striped bass fishery."
Research in Massachusetts is important because commercial and recreational fishermen landed 7.3 million striped bass in 2000, Ferry said. That's 40 percent of the catch along the entire Atlantic migration route of the bass.
As she described her field work, I would have loved to be a research assistant. I'm far from qualified.
It appears that the kind of local knowledge developed by fishermen can lead to scientific insights. To sample the stripers, Ferry organized a group of charter captains and had them fish with standardized techniques.
The idea was to assign two experts per boat and to fish the lower two to three miles of each river during the ebb tide, for four to six hours around first light.
They fished with fly and spinning equipment, but could not use bait. The study included an examination of stomach contents, so swallowed bait would invalidate the sample.
To me, the real revelation of the study is that the experts could come to a consensus on the most effective fly patterns and lures: bucktail jigs and soft shad-body lures, and flies tied as Clouser minnows and deceivers. Color pairing of chartreuse and white, and olive and white accounted for three-quarters of the fish. Ferry divided the study into two regions, nine rivers above Cape Cod and four in the Buzzard's Bay area south of the cape. The cape is what Ferry described as a "faunal break." Many species remain above or below the dividing line between warmer and colder ocean waters.
The experts fished for stripers and science in the spring, summer and fall.
In the spring, and the beginning of the migration, they caught plenty of stripers in both the northern and southern rivers.
The northern rivers remained strong in the summer, but the southern rivers saw a drop-off.
In the fall, the stripers continued to hit lures and flies in the northern rivers, but most of the fish had deserted the southern rivers with a couple of important exceptions.
Not surprisingly, water temperatures have a lot to do with fishing success. Ferry said bass tend to seek out water that is about 70 degrees. Most of the rivers in the Buzzard's Bay area get too warm for the species.
Ferry's field work wasn't all fun and games. Researchers had to examine the stomach contents of all 4,000 fish. This was done through a process called "gastric lavage," using a tube to flush out the stomach with pressurized water.
The study confirmed the theory that stripers come north to eat, and that they will consume almost anything they can wrap their mouths around.
There was good news and bad news for anglers.
The bad news is that much of the diet consists of shrimp so tiny that Ferry was surprised a predator fish could eat them. Apparently they are sucked down a thousand at a time.
"We saw more of these little shrimp in the bass than anything else," she said. "It was kind of like oatmeal for the fish."
Good luck finding a fly pattern to match them.
The good news is that those flies and lures designed to imitate Atlantic herring, sand eels, silversides and menhaden match what Ferry and associates found.
Seining the rivers to sample both baitfish and invertebrates confirmed what was found in the stomach samples.
The research also confirmed the summer doldrums that frustrate many anglers. Ferry's experts had their best angling success during the spring and fall migrations. The fish seemed reluctant to take anything during the hottest weeks.
"Perhaps that is when the fish are kind of toughing it out, waiting for the big blitz in the fall," Ferry said.
Scientific research is similar to fishing in that learning a little about a topic always suggests new ideas that must be explored. It's like Patriots fans and the Lombardi Trophy. Once we get two or three, we only want more.