Stories from the field: Seining
Ethan St. Aubin has added another skill to his experiences as a summer intern for DSF - seine fishing. Here is his report:
Overlooking the critical Pleasant River is the Columbia Falls office and hatchery of the Downeast Salmon Federation It is here where an ongoing seine survey of river herring, alewife and blueback herring takes place. Right below the building is the remnant of the removed dam and fishway adjacent to the estuary which is created where the freshwater of the river meets the salt water of the ocean. In the brackish habitat you can find many species including river herring, salmon, smelt and other anadromous fish, fish that spawn and breed in freshwater and then spend most of their adult lives in the ocean. In fact, the estuary in Columbia falls is home to several smelt shacks and an annual smelt fry. Smelt are a favorite snack for Atlantic salmon.
A seine net is long and fine meshed with a large bag in the middle. Deploying the net requires at least two people and the goal is to create a sweeping arc through the water to herd the fish towards the bag. The bag is then brought to shore to look for the catch, you have to stay vigilant because some species can slip through like eels! Bycatch species are safely released back to the water and target species will soon join them but are first measured and recorded.
Seine surveys are important for many reasons. The yearly surveys allow DSF and other organizations to build a history of river herring and other species of interest. The history can be referred to in order to see trends in population and fish size. Additionally, the records can be used to predict future catches once enough data has been collected. A goal of the project is to use the data to back up successful conservation efforts or inversely, that stressors like pollution or lack of rain are harming fish populations. Only time will tell which case is true (hopefully it's the first one)!