Monday, February 14, 2011

Checking in on Quilcene Coho Salmon!

A month has passed since staff from our office and Quilcene National Fish hatchery released the first group of coho salmon juveniles (fry) into the upper portion of the Big Quilcene River (see January 11 post).

We recently took a trip to the river to see where the fish have moved and to see if they are feeding and growing since leaving the hatchery. Our hope was that, once in the river, many of these fry would move around to find suitable shelter and food so they would stay healthy and continue to grow. And since we recorded the locations where fish were released, we were able to go back and see how many decided to stay where we planted them and how many had moved away. This information is important for several reasons--first, it allows us to determine if we are releasing the fry into areas that are good for growing coho salmon; and second, we can determine how many fry we can release into the area without overcrowding them.

There are several ways that biologists and technicians at our office count fish in streams and lakes. One way that is preferred by our office is to perform a snorkel survey. This method does not harm the fish because they are never caught with nets and handled. Visual counts by snorkeling are performed while the fish are active at night--this is when the fish come out of hiding from the stream banks and bottom to search for food in open water. The fish are less startled during the night and we can often swim beside them and watch as the coho look for insects and other natural food to drift by in the open water areas of the stream.

During our recent trip to the Big Quilcene River, we were able to snorkel several areas where we had planted juvenile coho this year and the findings were positive. Many of the fry moved downstream from the release locations and are now using more of the river to feed and grow; however, many of the fry found a suitable home right where we released them. The coho salmon fry all looked healthy as we swam around watching them search for and munch on natural food items. As the fry continue to grow, they will move further apart from each other, ensuring that they will have plenty of food and shelter. Hopefully they will keep growing and eventually leave the Big Quilcene River for Hood Canal and the Pacific Ocean before returning a few years later as 8- to 20-pound adult salmon.

Wednesday, February 2, 2011

Determining the Age of Salmon Produced at Federal Hatcheries

the USFWS Lacey office collects biological information from a portion of each returning salmon run at Makah, Quilcene, and Quinault National Fish Hatcheries on the Olympic Peninsula. We record sex, length and species for each fish. We also collect scales from the side of the fish behind the dorsal fin to determine the age of the fish. These scales are placed on an adhesive strip on a card and returned to the office for analysis.  Back at the office, each scale card is imprinted onto an acetate sheet using heat and pressure. The acetate sheets are then magnified with a microfiche reader so that the scales can be easily seen.

Rings (called circuli) form on each scale just like rings on tree trunks. The circuli are visible in the lighter area of the scale. The darker banded areas are called annuli--they are formed during the winter months when the fish grow more slowly. We can estimate the age of each fish by examining these rings. 

The age data we gather is then used to estimate the age and survival rate of the returning salmon. 

Here are some videos demonstrating the scale collection/analysis process: