November 6, 2017 at 5:05 pm
By Brian Lewis, IFW Fisheries Biologist
[caption id="attachment_2534" align="alignright" width="545"]
A trapnet has outstretched wings with funnel fish towards the center where they are become trapped. After fish are weighed and measured, they are released.[/caption]
The sun is bright, the air crisp, and bright leaves crunch under foot. Sure enough fall has arrived and your local biologist’s thoughts are turning to salmon. Each fall biologists across the state utilize various fish capture techniques to get their hands on a sample of landlocked Atlantic salmon from a variety of waters to evaluate their growth and condition. Information gathered during these fall sampling events form a valuable piece of the salmon fishery management puzzle and are used to evaluate the current condition of the population, as well as forage abundance (usually smelt). Our findings often act as a catalyst for future regulation and/or stocking changes.
Here in the Sebago Lakes region we commonly utilize three different methods of salmon capture. The first, and most common throughout the state is the use of trapnets. These live capture nets take advantage of the adult salmon’s pre-spawn habit of cruising the shoreline of a lake in search of moving water that might indicate the presence of suitable spawning habitat. A blocking seine called a “lead” is set at right angles to the shoreline which serves to interrupt the salmon’s path and directs them into deeper water where a box trap awaits them. Inside the box is a reverse funnel, which makes entry much easier than exit and allows biologists to capture numbers of salmon with a minimal effort. Captured salmon are weighed, measured, and aged by fin clip or by scale sample, and then released to continue with their fall spawning instincts.
[caption id="attachment_2536" align="alignleft" width="408"]
All fish are measured, weighed, and a scale is taken to determine age if there is no fin clip designating a hatchery fish. The combination of biological data provides biologists with a glimpse into the health of the fishery.[/caption]
The second method used in this region is a concrete fish trap situated beside the dam on the Jordan River in Raymond. Here, salmon from Sebago Lake ascend the Jordan River following their spawning instinct and are re-directed into a building housing several concrete pools. Fish are collected over the course of a few weeks, and separated by age/sex until early November. When they are ready to spawn, fish culturists from the Casco Fish Hatchery strip the eggs and milt from the salmon to form the next generation of salmon to be stocked in southern Maine lakes. Regional biologists use this opportunity to collect a sample of fish to evaluate the population structure and growth of salmon in Sebago Lake. The advantage to this technique is that biologists can get a sample in a matter of hours instead of the days (and sometimes weeks) of effort required of trapnet sampling. Regional biologists have been sampling salmon in this manner since the late 1960s which makes for a useful long term database.
The third method of adult salmon sampling utilized in Region A is unique to the region, unique to Lake Auburn, and is probably the most enjoyable. Salmon again, following their instinct to spawn, swim up the outlet of The Basin at the north end of Lake Auburn until they are stopped by a dam. The habitat below the dam is attractive enough so the salmon attempt to spawn and thus congregate there by the dozens. Fishery biologists block the lower section of the stream with a blocking seine to hinder escape and use a backpack electrofishing unit to temporarily stun the salmon and collect them for evaluation. Length, weight, and age data are collected and the fish are released alive back into the river to continue their spawning efforts.
Southern Maine biologists begin sampling efforts around the third week of October and I have to say I can’t wait. This biologist gets to spend the next three weeks outdoors enjoying some of the best weather Maine has to offer, while admiring some truly excellent Maine landlocked salmon. I encourage the reader to spend some quality time outdoors this fall, fishing, hunting, or just simply enjoying nature.
[caption id="attachment_2537" align="aligncenter" width="1024"]
An electrofishing backpack allows biologists to temporarily stun a fish so it can be netted, then later weighed and measured. Here IFW fisheries biologists are shocking and sampling a tributary into Lake Auburn.[/caption]
A trapnet has outstretched wings with funnel fish towards the center where they are become trapped. After fish are weighed and measured, they are released.[/caption]
The sun is bright, the air crisp, and bright leaves crunch under foot. Sure enough fall has arrived and your local biologist’s thoughts are turning to salmon. Each fall biologists across the state utilize various fish capture techniques to get their hands on a sample of landlocked Atlantic salmon from a variety of waters to evaluate their growth and condition. Information gathered during these fall sampling events form a valuable piece of the salmon fishery management puzzle and are used to evaluate the current condition of the population, as well as forage abundance (usually smelt). Our findings often act as a catalyst for future regulation and/or stocking changes.
Here in the Sebago Lakes region we commonly utilize three different methods of salmon capture. The first, and most common throughout the state is the use of trapnets. These live capture nets take advantage of the adult salmon’s pre-spawn habit of cruising the shoreline of a lake in search of moving water that might indicate the presence of suitable spawning habitat. A blocking seine called a “lead” is set at right angles to the shoreline which serves to interrupt the salmon’s path and directs them into deeper water where a box trap awaits them. Inside the box is a reverse funnel, which makes entry much easier than exit and allows biologists to capture numbers of salmon with a minimal effort. Captured salmon are weighed, measured, and aged by fin clip or by scale sample, and then released to continue with their fall spawning instincts.
[caption id="attachment_2536" align="alignleft" width="408"] All fish are measured, weighed, and a scale is taken to determine age if there is no fin clip designating a hatchery fish. The combination of biological data provides biologists with a glimpse into the health of the fishery.[/caption]
The second method used in this region is a concrete fish trap situated beside the dam on the Jordan River in Raymond. Here, salmon from Sebago Lake ascend the Jordan River following their spawning instinct and are re-directed into a building housing several concrete pools. Fish are collected over the course of a few weeks, and separated by age/sex until early November. When they are ready to spawn, fish culturists from the Casco Fish Hatchery strip the eggs and milt from the salmon to form the next generation of salmon to be stocked in southern Maine lakes. Regional biologists use this opportunity to collect a sample of fish to evaluate the population structure and growth of salmon in Sebago Lake. The advantage to this technique is that biologists can get a sample in a matter of hours instead of the days (and sometimes weeks) of effort required of trapnet sampling. Regional biologists have been sampling salmon in this manner since the late 1960s which makes for a useful long term database.
The third method of adult salmon sampling utilized in Region A is unique to the region, unique to Lake Auburn, and is probably the most enjoyable. Salmon again, following their instinct to spawn, swim up the outlet of The Basin at the north end of Lake Auburn until they are stopped by a dam. The habitat below the dam is attractive enough so the salmon attempt to spawn and thus congregate there by the dozens. Fishery biologists block the lower section of the stream with a blocking seine to hinder escape and use a backpack electrofishing unit to temporarily stun the salmon and collect them for evaluation. Length, weight, and age data are collected and the fish are released alive back into the river to continue their spawning efforts.
Southern Maine biologists begin sampling efforts around the third week of October and I have to say I can’t wait. This biologist gets to spend the next three weeks outdoors enjoying some of the best weather Maine has to offer, while admiring some truly excellent Maine landlocked salmon. I encourage the reader to spend some quality time outdoors this fall, fishing, hunting, or just simply enjoying nature.
[caption id="attachment_2537" align="aligncenter" width="1024"] An electrofishing backpack allows biologists to temporarily stun a fish so it can be netted, then later weighed and measured. Here IFW fisheries biologists are shocking and sampling a tributary into Lake Auburn.[/caption]Categories