Study of Dolly Varden and Arctic Char Population in the Ugashik Narrows, Alaska

Student Investigator: Mia Baylor

Advisor: Dr. Joseph Margraf

Introduction

The Upper and Lower Ugashik Lakes are located 560km southwest of Anchorage on the Alaskan Peninsula. The lakes are within the boundaries of the Alaska Peninsula National Wildlife Refuge. This is a remote area that is only accessible by boat through the Ugashik River or by floatplane. The lakes are fed mostly by tributaries whose origins are in the Aleutian Range to the east of the lakes.

A sport fishery exists in an area called the Ugashik Narrows. This body of water connects the two lakes and is approximately 0.5 km in length. The Ugashik Narrows has two main channels with moderately fast flowing water. This area is the primary spot for sport fishing in this system. In 1998 there were 3 operational lodges and 1 inactive lodge located on the perimeter of the Ugashik Lakes. There is potential for new lodges to be built and an increase in fishing pressure, as there are private lands available for such use.

In 1998 there were 348 angler trips to the Ugashik Narrows from June 20- September 14, only three fished by boat. Arctic graying, Coho Salmon, Sockeye Salmon, Pink Salmon, Arctic Char and Dolly Varden Char as well as Lake Trout were all documented in these angler's catches. The primary target species in this system is the Arctic grayling; however, it is estimated that 878 Arctic char or Dolly Varden char were caught that year. Out of this, 23 were harvested (Jaenicke 2000). The regulations for this area allow harvest of 3 Arctic char or Dolly Varden per day with no size limit.

With a potential for increased fishing pressure in the Ugashik Narrows there is a possibility that more fish will be harvested as well as more sport fishers to use boats and target other areas of the system. Because this area is a relatively unexploited with very low harvest rates, it is a great opportunity to learn some baseline management data before a fishery exists.

Some information is known about Arctic Char (Salvelinus alpinus) and Dolly Varden Char (Salvelinus malma) in many different areas around the globe. These fish are often confused and even considered the same by some scientists. However when specific features are closely examined they become two distinct species with often overlapping habitats and life histories (Balon 1980). Both Dolly Varden and Arctic char have exhibited anadromy in some areas with Dolly Varden moving up to 1690km (DeCicco 1992), and others remain residents in lakes (Scanlon 2000). These fishes life histories seem to be unique to every situation (Gudkov 1996). There have been some studies on the sport fishing in the Ugashik Narrows (Meyer 1991) which have looked at Dolly Varden and Arctic char, but there has been no previous biological data or any tagging program in this area. Very little is known about this system in general.

Objectives The objectives of this study are to (1) document the size distribution and proportion of Dolly Varden and Arctic char in the Ugashik Narrows in June, (2) estimate the abundance of Dolly Varden and Arctic char in the Ugashik Narrows in June, and (3) characterize the fishery in the Ugashik Narrows during June.

2002 Methods

Dolly Varden and Arctic Char were captured in the Ugashik Narrows in June, July and August. 60' and 200' l-inch mesh beach seines were used to collect fish. The 200' seine was 10' deep and the 60' seine was 6 feet deep. Hook and line was also used to collect fish at times when it was not possible to use the seine. Sampling was conducted as weather permitted and also at times to cause the least amount of disturbance to the sport fishers in the area. The fish were caught and held in an in-water holder pen until they were ready for tagging.

In July, 13 Dolly Varden were radio tagged. These fish were examined prior to tagging to ensure that they looked healthy and weighed at least 450g. The radio tags each weigh 8.9g. It was necessary to tag a fish so that the radio tag weight was not greater than 2 percent of the fish's body weight. These fish will be anesthetized in a 30mg/L solution of clove oil and tags will be surgically implanted into their body cavity. Once implanted, the tags will emit a signal every 5 seconds for 16 weeks. This will include, July, August, September and October 2002. The tags will then be turned off for 32 weeks and then tum back on June 7, 2003. The Narrows was scanned once a day and time, date and location was noted for each individual fish.

In June, July and August, all Dolly Varden and Arctic char caught in the Ugashik Narrows were anesthetized with a 30g/L solution of clove oil and tagged with both a Vialpha tag and small shrink-wrapped silver colored Floy tags. Each tag has an individual code to identify each fish. Biological data was taken from each fish as long as mortality remained low and samples were not too large to handle. Mid-eye to fork length (nearest mm), total length (nearest mm) and weight (nearest g) was documented for each fish sampled. After being tagged each fish was placed in a recovery box until alert enough to be released. Operculum movement was monitored to ensure each fish remainined stable during the tagging process. Gear type, time, date, location and water temperature was documented for each set. Other species in each sample were documented.

The Ugashik Narrows was sampled throughout the summer to document the presence of tags. Presence of tags was documented and fish sampled without tags were tagged in the manner described above and released as well.

Results

During June, July and August 2002, 21 Arctic Char were captured and 2 were recaptured using all methods. The mean length of the Arctic Char was 432 mm and the mean weight was 1.4 kg. Two hundred and nine Dolly Varden were captured and 54 were recaptured. The mean length for the Dolly Varden was 482 mm and the mean weight was 1.6 kg. Tag loss was calculated by examining the recaptured fish for both the floy and vialpha tags. Overall there were 55 recaptures, nine were missing a vi tag and 3 were missing a floy tag. The calculated total tag loss was 1% (Table 1).

Number of Fish Vi Absent Vi Present Total Floy Present 0.6 3.0 3.6 Floy Present 9.0 43.0 52.0 Total 9.6 46.0 55.6

Percent Tag Loss Vi Absent Vi Present Total Floy Present 1% 5% 7% Floy Present 16% 75% 93% Total 17% 83% 100%

Table 1

The radio tracking showed that the Dolly Varden and Arctic Char moved out of the Ugashik Narrows. Each of the thirteen radio-tagged Dolly Varden left the narrows within 1 week of being tagged. Two tags were found on shore as these fish died for unknown reasons. There is no evidence whether the other radio tagged fish survived but they were not in the Ugashik Narrows.

Analysis

Preliminary data analysis shows that the populations of Dolly Varden and Arctic Char in the Ugashik Narrows change throughout the summer. It was extremely difficult due to weather and Sockeye Salmon conditions to adequately sample during July and August. The Dolly Varden and Arctic Char seem to follow the patterns of the Sockeye Salmon migration, but due to the great numbers of fish in the area it was difficult to know for sure. The population size remains unknown as so many fish are moving in and out of the Ugashik Narrows and data has only been gathered from one year.

Management implications

Because the population size and movement patterns of the Dolly Varden and Arctic Char are very complex and not well documented a conservative approach to management should be taken. Currently the regulations state the 3 Dolly Varden/ Arctic Char can be harvested per person per day and the stock is relatively unexploited, but as more people use this area and take their maximum limit the status of these fish could change very quickly. These species are grouped together as one in the regulations, but it seems evident even from this preliminary data that the Dolly Varden and Arctic Char are not present in the system in the same numbers and sizes. It is difficult for scientist to tell the species apart as well, but with some education to the public on theses species they could more cleary tell apart the Arctic char and Dolly Varden. Future Plans

In the 2003 field season we will attempt to locate the previously radio tagged fish to see where they are in the system. Attempts will be made to concentrate intensely during the month of June while sampling conditions are more optimal. This was a month when many guided anglers were in the system and it seems like it would be very important to know about the system more during this particular time. Seines will be used again in areas that permit. A trap net will also be used to catch the fish. It will be set up as a barrier across the narrows and a seine net will be used to herd the fish towards the trap net. This is in the hopes that it will be more efficient in catching the fish. The area will be sampled on the edges of the Ugashik Narrows as well as within the area. We will try to document weather or not fish are leaving and entering the system during this time. If there are many fish on the edges it will be more difficult to come up with a population estimate, but if there are never any fish on the edges we may be able to say that it is a more closed area during a certain time. Attempts will be made to characterize the fishery by surveying the angler's catches and how they feel about the fishery. All fish captured will once again be tagged, but with only the Floy tag since it had much lower tag loss rates.