Species restoration

Eco-evolutionary dynamics in species restoration

We integrate ecological, evolutionary and genetic studies towards:

1) Improving strategies to achieve desired demographic effects through captive rearing/breeding and supplementation

2) Increasing the likelihood of success in reintroduction and restoration programs of endangered species or distinct populations

Lake Champlain Atlantic Salmon Restoration

The restoration efforts to bring back the Atlantic salmon populations to Lake Champlain started getting serious in the 1970s. Each year hundreds and thousands of Atlantic salmon fry and smolt are stocked into the rivers and lake in an effort to promote the establishment of this economically and socially important species. In order to achieve their goal of re-establishing the lake’s salmon populations, the regulatory bodies responsible (U.S. Fish and Wildlife Service, Vermont Fish and Wildlife, New York Department of Environmental Conservation) have taken a unique approach, starting from the lake and working towards the rivers. This strategy of starting with the lake has resulted in the creation of a healthy salmon fishery within Lake Champlain that brings economic gains both the Lake Champlain area as a whole and to the fishery management groups.

CHALLENGES ENCOUNTERED

Several issues, such as changes in sea lamprey abundance and periodic low water levels have hindered the restoration of Atlantic salmon over the years, though progress is still being made. Beginning in 2001, increasing numbers of sea lamprey wounds on salmon and trout in Lake Champlain coincided with a decrease in the number of spawners observed in the Boquet and Winooski Rivers. Increased effort by the USFWS in treating for sea lamprey have been successful at decreasing the number of wounds observed on salmon, though the number of spawners seen each year has been slow to recover. Low water levels are believed to be partly responsible. Another possible explanation may be something far less obvious.
Atlantic salmon, like most members of the salmonidae family of fishes, embark on migrations several times throughout their lives. The first migration occurs at an early stage when fish move from the streams and rivers where they hatched to the oceans or lakes where they will mature. By giving up the relative safety of the streams for the food rich environments in the oceans and large lakes, salmon can grow to be very large in a short period of time. But many of the species that adult salmon prey upon would themselves prey upon juvenile salmon when given the chance. It is for this reason that mature adults embark on a second migration back to their natal streams in order to produce the next generation of juvenile salmon in the relative safety of the stream environments, beginning the cycle over again. Adult Atlantic salmon may then return to the ocean or lake to repeat their migration in the next spawning season.
How salmon are able to make such extensive migrations and then find their way back to the exact streams in which they were born is not precisely known. What is known is that their sense of smell plays a vital role. Salmon create a mental record of their home stream when they are young based largely on smell. This is called imprinting. Once the salmon have grown into adults and are ready to spawn, they simply follow their nose to get back. The period during which salmon create this mental record varies from species to species and from population to population and must be taken into consideration when stocking fish from a hatchery into the wild.
This imprinting period makes the job of a biologist trying to restore a wild population a real balancing act. On one hand, larger, older fish tend to survive better than younger smaller fish when stocked into the wild. On the other hand, fish that are kept in the hatchery too long may imprint on the hatchery’s smell rather than that of the stream they are stocked into. As a result they have great difficulty migrating back to spawn.

 

OUR RESEARCH GOALS

To determine whether the low numbers of spawners observed in the Boquet and Winooski Rivers are the result of fish being stocked ‘too late’ the USFWS has teamed up with Concordia University in Montreal, Quebec to conduct an experiment. Between 2011 and 2013 the USFWS stocked the Winooski and Boquet Rivers with two types of Atlantic salmon smolts: the first (control) group was identical, in every way, to what has been stocked into these two rivers historically, the second (experimental) groups were stocked earlier in the Boquet River and at a smaller size in the Winooski River. All of these fish were marked before being stocked by removing their left ventral fins like in the example below.

HOW YOU CAN HELP

We are now seeking the assistance of anglers in the Lake Champlain area. With sampling kits we can provide, you can send us information and a scale sample from LV clipped salmon you catch in the Lake Champlain Basin. By doing so you’ll be helping us improve the chances of the salmon restoration being successful. We can provide any interested anglers with sampling kits that contain everything you’ll need to collect samples as well as instructions. You can also check out the video below for more instructions on how to collect a scale sample. Samples can then be mailed back to the USFWS using the prepaid envelopes provided. For more information call the US Fish and Wildlife service at (802) 872-0629.