William T. Fairgrieve

Effects of various feed supplements containing fish protein hydrolysate or fish processing by-products on the innate immune functions of juvenile coho salmon (Oncorhynchus kisutch)

Abstract Immunomodulators administered to fish in the diet have been shown in some cases to enhance innate immune defense mechanisms. Recent studies have suggested that polypeptide fractions found in fish protein hydrolysates may stimulate factors in fish important for disease resistance. For the current study, groups of coho salmon were reared on practical feeds that contained either fish meal (Control diet), fish meal supplemented with cooked fish by-products, or fish meal supplemented with hydrolyzed fish protein alone, or with hydrolyzed fish protein and processed fish bones. For each diet group, three replicate tanks of fish were fed the experimental diets for 6 weeks. Morphometric measurements, and serologic and cellular assays were used to evaluate the general health and immunocompetence of fish in the various feed groups. Whereas the experimental diets had no effect on the morphometric and cellular measurements, fish fed cooked by-products had increased leucocrit levels and lower hematocrit levels than fish from the other feed groups. Innate cellular responses were increased in all feed groups after feeding the four experimental diets compared with pre-feed results. Subgroups of fish from each diet group were also challenged with Vibrio anguillarum (ca. 7.71×10 5 bacteria ml −1 ) at 15 °C by immersion. No differences were found in survival among the various feed groups.

Evaluation of Endocrine Indices of Growth in Individual Postsmolt Coho Salmon

Abstract Plasma levels of the hormones insulin and insulin-like growth factor-I (IGF-I) were assessed as indices of growth for individual juvenile coho salmon Oncorhynchus kisutch. Smolts were tagged in April, introduced to seawater in May, and reared at two different feeding levels. Fish lengths and weights were obtained in June, August, September, and November. Plasma samples were obtained in September and November. There was a consistent, robust relation (over both feeding rates and sampling dates) between plasma IGF-I and the instantaneous growth in length of individual fish when growth was measured over a 6-week period. There was no consistent association between plasma insulin level and growth, size, or condition factor. Plasma IGF-I levels were also measured in postsmolt coho salmon captured in September from the Strait of Georgia and Puget Sound and were found to be similar to those in laboratory fish.

Reproductive Investment and Growth History in Female Coho Salmon

Abstract The body size, ovary mass, egg mass, and fecundity of coho salmon Oncorhynchus kisutch from three different rearing environments (wild, ranched, and captive) were compared to determine which aspects of growth history affect changes in these reproductive characters. In addition, the growth of individually tagged females reared in captivity throughout the seawater growth phase was measured and related to final reproductive investment. A strong positive relationship existed between ovary mass and body length at spawning; this relationship was maintained over a wide range of final body sizes, and the regression slope was consistent among the rearing environments. However, the relative investment in ovary mass and fecundity (regression intercepts) differed between rearing environments. Fish reared in captivity throughout their life cycle had higher values than did fish reared in the other two environments. A relatively weak positive relationship between egg mass and final body length was common to fem...

Interactions of Atlantic salmon in the Pacific northwest: V. Human health and safety

The paper discusses potential issues for human health and safety from net-pen salmon farming in the Pacific northwest region. A brief introduction to global and national responsibilities for food safety is followed with a review of the chemicals and chemical contaminants in materials used in farm production operations. Possible sources include metallic paints, feed ingredients, and chemotherapeutants. Concerns for the transmission of diseases follow, and the common pathogenic diseases are reviewed. After a section on the processing and quality of farm products, specifically the proximate composition of farm fish and differences between farm and wild salmon species, the concerns for worker safety on the farm are considered. The paper ends with some conclusions on the varying degrees of risk carried by these issues.