Week 2: Collecting Preliminary Data
- emilyvanvlack
- Jun 3, 2017
- 5 min read
May 30, Tuesday:
Our second time out in the field. Today, myself, Dr. Pinou, and Luke spent our entire day out in the Danbury Bay, sampling from 10 predetermined sites in addition to some scans preformed around the original stocking sites of the fish by Danbury Town Park.
We saw extremely favorable results today, finding at least one fish at nearly every location that we collected our data from. While we expected to find fish in the Danbury Bay, as it contained four of the original stocking sites for the carp, the weather was overcast and very windy, decreasing the likelihood that we would be able detect the fish in shallow water with the receiver. Furthermore, the data collected today bodes well for the carp program as the Danbury Bay contains some of the largest Milfoil beds in Candlewood Lake. From the results obtained today, it seems that many of the fish originally released in Danbury have decided to remain and consume the Milfoil growing there, which is what we hope to see with the carp program.
However, something to consider, and which needs to be proved to the State Department of Environmental Protection is whether or not the tagged fish are alive and eating Milfoil, or if the tag is attached to a dead fish at the bottom of the lake. Another concern to consider is whether or not the radio tags are still attached to the fish. As the fish grow, there is potential for the tag to fall out, so much of the data collection this summer will be aimed at proving that these tagged fish are still alive and well. It is often difficult to tell with just one visit to a site if the fish is on the move, as grass carp are, for lack of better words, extraordinarily lazy. Therefore, the goal is to visit all sites on the lake (a map of the sites will be posted on the blog within the coming weeks for those interested in the locations) as frequently as possible during the summer months to hopefully observe movement of the fish we are finding from one site to another.
The image above depicts the radio receiver for the 50 radio tagged carp in use. Each site we visit is scanned for each of the 50 carp at least once, with equal amounts of time spent on the channels for each carp. We devote more time listening to the channels of carp in which we find in a given site in an attempt to pinpoint their location and proximity to our boat.
Special thanks to our volunteer boat captain Frank!
Exciting news for the town of New Fairfield, the vote against the addition of chemicals to Candlewood Lake passed! It was wonderful to see so many people from the town turn out to support the lake. Great news all around!
June 1, Thursday:
As no boats were available today, Luke and I opted to make the most of the beautiful weather by taking data points from the shoreline by the Sherman Town Park.
Pictured above is the map of the Sherman Arm of the lake. Test sites are denoted by yellow stars, and original release sites are denoted by blue stars. Today, we focused only on the most northern two points, the original release points of the fish in Sherman. In addition, we scanned several sites along the narrow cove of the Sherman Town Beach Marina. At this point, we are attempting not only to locate the fish via their radio tags, but to pinpoint their exact locations in order to determine their viability as living subjects.
At additional unmarked sites, we take a GPS reading of the precise latitude and longitude to mark the location, and then use the receiver to listen for fish we've heard at marked sites. This allows for a more accurate location of the fish.
As stated above in the Tuesday section of this post, a key point of the carp study is to prove that the fish are alive and well, and that the radio tag is not sitting at the bottom of the lake. We thought that Sherman would be an ideal location to attempt to induce movement of the fish due to the fact that the lake is very narrow near the Sherman Town Park, and that we were able to identify the presence of 6 carp concentrated around this area. From the shoreline, we tried to disturb the water with branches and noise to scare the marked carp. Although this method may seem crude, it is necessary to cause a disturbance to convince the fish to move, as grass carp are sluggish, and often can be nearly sedentary for long periods of time.
While we were able to confirm the presence of 6 carp around the Sherman Town Park, we also found that, at least from the shoreline, our disturbance tactics did not effect the carp enough to induce detectable movement. Therefore, we now know that in order for this portion of the research to be successful, a more effective method is required to determine the condition of our tagged carp.
June 2, Friday:
After the lack of success yesterday in determining if our 6 carp found off of the Sherman Town Park were alive and well, Luke and I decided to come back with kayaks to conduct a broader search.
Right off the bat, we discovered some positive news. While preforming scans of the same areas we had collected data from yesterday, we discovered that one of the fish found the other day had disappeared, and that another had moved out of range from one spot but could be heard in another. This data suggests that at least two of the six tagged fish are definitely alive and eating Milfoil around the Sherman beach. While we were unable to conclusively determine movement of any of the other four fish heard yesterday, we were able to pinpoint their location in the lake, which is necessary data for our continued tracking this summer.
In addition, we once again tried to cause disturbance from the surface of the water in which we approximated that the remaining four fish were residing. Splashing about with our paddles, the presence of our boats, and even activity of some motor boats in the Marina did not result in any significant movement of the tagged carp. The likely explanation for this, is that the fish are either too deep down, or too far away from the site of disturbance to care. However, the fact that the fish did not move tells us that we cannot artificially induce the carp to move in order to prove their vitality. We will unfortunately have to rely on the fact that they should eventually leave their current locations, and move to a new area where food is plentiful as we continue to collect data throughout the summer.
While we did not see any carp while kayaking, we did see a Northern Watersnake swimming alongside the Sherman beach. While we were surprised to see this guy, it is nice to know that Candlewood Lake provides a home for so many organisms!
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