David G Brown, Student Technican
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Posted on July 8, 2011 | Permalink
Student Technican Experience - Week 2
I had another good week working as a student technical assistant for the Fisheries Service. On Wednesday I got the opportunity to visit the Joseph Manning Hatchery in Brandywine with the Tidal Bass Manager Dr. Joe Love. I was given a tour of the large hatchery which had many ponds and tanks for raising fish. I was able to see the copious amount of fry in the round tanks. The biologists who worked there explained to me that water is pumped out of some of the ponds into the tanks so the fry can eat the small organisms that live in it. The fish in the tank are raised until they get to a certain size then they are released in to the wild or a pond at the hatchery where they will grow some more. The fry that I saw were mostly bluegill and bluegill sunfish hybrids. After the tour, it was time to get to work. Our job for the day was to fish for largemouth bass in one of the ponds. We needed to catch the adult bass and take them out of the pond because the fish were full grown and were eating some of the smaller fish. Dr. Love, another biologist Branson, and I all got our fishing poles and tackle and headed out to the pond. For bait, I used a rubber worm on a hook and the others used various lures. It was very difficult to fish in the pond though because there was a lot of underwater grass and every time we would cast out our lures we would always be pulling up clumps of grass. It ended up being a pretty slow day of fishing. We only caught three bass and I caught them all but we were told that there were around twenty in there so we barely made a dent. Despite the fishing being slow, it was still fun and a good experience. I have never caught a bass on a rubber worm and I didnít think that the bass would go for it but they did.
After fishing, we went to the office located on the hatchery, there Dr. Love showed me how to identify the age of a bass. I assisted Dr Love, who likes a second opinion on how many rings there are within the otiliths. Dr. Love explained to me that to identify the age of a bass, you have to count the rings you see on the inside of the fishesí ear bone. The otolith or the ear bone grows as the fish grows. In the cold weather when the fish grow very slowly, the otolith grows slower and is very dense while in the summer when the fish grow fast the otolith grows faster and thinner. The parts of the otolith that are denser appear dark and the thinner, less dense part of the bone shows up light in color. To age a bass you have to cut the otolith in half to expose the rings, take of picture of it, and then count the amount of dark rings. The number of dark rings in the otolith is the number of winters the bass has lived through. Aging bass this way only works for areas that have cold winters because in areas that are warm year round, the fish grow all year and dark rings are not visible on the otolith. I aged several bass but it was difficult sometimes to see the rings so Iím not sure if I aged them all correctly. Overall, going to the Joseph Manning Hatchery was a good experience for me and I learned a lot about largemouth bass.
On Thursday the 7th, I had a great experience working with striped bass for the first time. The day started off early at 5am at Kent Narrows where I met Mr. Eric Durell and two other biologists. We got the boat loaded and ready and then we caught up with a waterman who let us measure the rockfish that he caught in his pound net. A pound net is a series of nets attached to posts that all work together to trap fish. A pound net has one long straight net, a heart shaped net, and a rectangular net that has a bottom to it. The long straight net is called the leader and it leads the fish into a heart shaped net that corrals them. The heart shaped net corrals the fish and leads them into the pound. The pound is a rectangular net that has a bottom to it so when the fish are all corralled in there, the waterman can just pull the net that is on the bottom and catch all the fish. The waterman we were with today pulled up his pound net and the first thing I noticed was the wide variety of fish. I was expecting to see mostly rockfish and croaker but there were blue crabs, horseshoe crabs, catfish, flounder, menhaden, and others. Once the fish were on the boat we got right to work measuring the rockfish and taking scale samples. We measured the fish in millimeters and we took scale samples by scraping a few scales off the top of the fish with a knife. Collecting the scale samples from the fish doesnít harm them and the scales will grow back. We measured a lot of rockfish and even though I was wearing gloves I still got stabbed by their sharp spines a couple times. After we were done collecting scale samples and measuring the fish, we had to put tags on the fish that the waterman was going to keep. The minimum size for striped bass is 18 inches so anything over that we tagged. The fish needed to be tagged because its Maryland law and the different color tags let people know how the fish was harvested. After, we tagged the rockfish our day was over and we headed back to shore. This was my first time working with rockfish and actually it is the first time I have ever seen a live one. It was a good experience and I had a good time working with the rockfish.