Testimony of Joseph Cloud,
Professor of Zoology, Department of Biological Sciences, University of Idaho
Before the U.S. Senate Committee on Environmental and Public Works
Subcommittee on Drinking Water, Fisheries and Wildlife
October 8, 1998

Introduction

Good morning Mr. Chairman and members of the committee. My name is Joe Cloud,and I am a faculty member of the University of Idaho and a member of the Washington State University / University of Idaho Reproductive Biology Center. My research expertise is the reproduction and early development of fish with an emphasis on salmonids. My objective in this testimony is to provide you with the rationale for and the feasibility of establishing a germ plasm repository or gene bank for threatened and endangered fishes.

Background

Many fish populations around the world are declining. Some of the causative factors that have contributed to these declines include over-fishing, habitat destruction or degradation, pollution and genetic introgression. Regardless of the causes, a decrease in the size of a population can result in a decrease in the diversity of genes within the population. Because many of the unique characteristics of the various fish stocks are genetic adaptations to local conditions, the loss of phenotypic characteristics within a population can be detrimental to the long-term survival of the population in its native habitat. Since a number of the causes for the declines in fish populations are due to the activities of the human population, many of the problems that contribute to these declines in fish populations can be corrected, but these corrective actions may require extended periods of time.

In order to reduce or reverse the declines in fish populations, fish hatcheries have been established to mitigate the loss of native spawning habitat and to enhance the reproductive output of fish stocks. Although fish hatcheries have generally been very successful in the production and rearing of fry, the resultant gene pools of the hatchery populations are not always the same as the native stock from which they were derived. Thus, although hatcheries have been an important tool in the enhancement of fish populations, they have some inherent weaknesses relative to the maintenance of the original genetic composition of fish stocks.

Therefore the establishment of germ plasm repositories for fish populations provides (1) a means to reestablish a population when factors that resulted in the population decline are corrected and (2) a backup for the inadvertent change in the genetic makeup of a population with the development of hatchery programs.

Gene Banks for Fish Populations

At present, the cryopreservation of sperm is the only functional means of storing fish germ plasm for extended periods of time. The freezing of sperm, the efficient packaging of semen, and the long-term storage of sperm in liquid nitrogen were initially developed many years ago by scientists to support the genetic improvement in the dairy industry. Using these same technologies coupled with the understanding of the differences between mammalian and fish sperm physiology, cryobiologists around the world have successfully developed protocols to freeze sperm from a wide variety of freshwater and marine species of fish. Given the progress to date, these or similar methodologies can probably be utilized to preserve the spermatozoa of all current fish populations. Additionally, since the storage time for fish sperm held in liquid nitrogen has been estimated to be greater than 200 years, the time scale for the storage period is more than adequate for a germ plasm repository.

The establishment of gene banks for fish populations is not a hypothetical suggestion; it is a program that has a successful track record. This technology has been utilized successfully by a number of different countries in the establishment of fish germ plasm repositories around the world as a component of efforts related to fish genetic conservation. Norway, for example, has initiated an extensive effort to collect and preserve the germ plasm of native Atlantic salmon that spawn in their rivers. In 1986 the Directorate for Nature Management in Norway established a national gene bank program for their native salmon. At present, their repository contains frozen milt from over six thousand individuals from 155 salmon stocks. Although there is no national program in the United States, there are regional programs involved in the collection and cryopreservation of fish sperm. In the Northwest, our laboratory at the University of Idaho in partnership with Washington State University and the Nez Perce Tribe has initiated the development of a gene bank for chinook salmon that spawn in tributaries of the lower Snake River. At present, our efforts have resulted in the cryopreservation of sperm from over 500 males from 12 tributaries. Our efforts were initiated in 1992 and continue to the present. Although our efforts have been limited by funding, we are determined to save at least a portion of the gene pool of these stocks.

The major disadvantage of a gene bank based on frozen sperm is that the reestablishment of an extinct stock requires extensive backcrossing or the use of androgenesis with eggs from a related stock. This problem has a simple solution - preserve both sperm and eggs. However, the cryopreservation of fish eggs, because of their relatively large size, has not been successful to date. Support for research efforts in this area is needed; however, this is a very challenging problem and will not be solved quickly.

Concluding Remarks

It is my belief that the human population has an intrinsic need and responsibility to preserve the genetic legacy of our fish populations. Genetic conservation of existing fish stocks is an important goal in itself, and as a component of programs designed to insure a viable and sustainable fishery under changing environmental conditions. With the constant threat of losing genetic diversity in specific native fish stocks as a result of declining population numbers or as a result of genetic selection pressures in hatcheries, the establishment of a program for the long~ term storage of fish germ plasm would serve as a back-up and insurance for the presently ongoing conservation programs.

There is an important caveat in the development of a fish sperm bank. This product is a genetic repository, and as such, it will not solve any population problems of a fish stock that is decreasing, nor will it directly result in more fish in the rivers. What a sperm bank will do is guarantee that the genes, or combination of genes, that make a fish stock unique will not be lost forever.