Epidermal growth in two mature female bottlenose dolphins, Tursiops truncatus, was investigated by following the movement of a cohort of tritiated thymidine-labeled epidermal cells for 59 days. The majority of the cells migrated in a cluster which was estimated to reach the skin surface in 73 days. We calculate that the outermost cell layer is sloughed 12 times per day. Turnover time and sloughing rate are estimated to be 1.7 times longer and 8.5 times faster than the respective values for epidermal cell kinetics in humans. This apparent inconsistency of slow transit time and rapid sloughing rate is reconciled by the convoluted structure of the stratum germinativum in the dolphin which results in a ratio of germinatival to superficial cells of 876:1. The stratum germinativum of dolphin epidermis appears to lack morphologically distinct, spatially segregated subpopulations of anchoring and stem cells. Dolphin epidermis has a large capacity for cell population, relatively long turnover time, and rapid sloughing rate. The adaptive advantages of these characteristics are discussed.

Heartworms, Dipetalonema spirocauda, are common in harbour seals, Phoca vitulina, that strand along the New England coast. Lice, Echinophthirius horridus, taken from a stranded harbour seal infected with seal heartworm carried three developmental stages of D. spirocauda. This is the first report of an intermediate host of the seal heartworm.

Two experiments were conducted to determine 1) the effect of iron supplementation and the quality of fish oils on dietary lipid peroxidation and 2) the concurrent effects of diet rancidity and iron overload on the growth and physiological response of rainbow trout. Semi-purified diets supplemented with graded levels of iron (0-6250 mg/kg diet as ferrous sulphate) were fed to trout for 12-36 weeks. The malonaldehyde (MA) concentration of the test diets increased as the iron levels in the diets increased indicating that iron catalyzed lipid oxidation was occurring. However, when ethoxyquin was added to the oils, the increase in dietary MA level was significantly reduced. Fish oils with an initial high peroxide value were more susceptible to iron-catalyzed lipid oxidation. The concurrent effects of diet rancidity and iron overload (greater than 86 mg/kg) led to the development of unique histopathological signs, poor growth and high mortalities in the trout. In contrast, when diet rancidity was low (less than 10 µg MA/g diet), the toxic level of dietary iron was greater than 1380 mg/kg diet. The concentration of iron in trout tissues, and the hematocrit and hemoglobin concentrations increased as dietary iron levels increased and were not affected by the degree of diet rancidity.

Histopathologic, ultrastructural, and negative-staining studies indicated that nodular lesions on the flippers, head, and necks of recently weaned, captive grey seals (Halichoerus grypus) were similar to sealpox lesions reported from several other species of seals. Virions associated with the nodules were characteristic of the parapoxvirus subgroup of pox viruses. Two of the three persons handling the seals developed nodular lesions similar to "milker's nodules," the characteristic lesion in persons infected with parapoxvirus. The clinical course of the parapoxvirus infection in both the grey seals and their handlers is described. It was concluded that although sealpox is transmissible to man, the mild clinical manifestations place it in the nuisance category of zoonotic diseases.

The issue of sustainability of salmonid culture has been the focus of considerable media coverage and debate between environmental activists and aquaculture industry stakeholders, particularly regarding the use of ingredients derived from wild fisheries (fishmeal and fish oil) in salmonid feeds. This study attempts to summarize recent data and to calculate the conversion efficiency of feed resources by Canadian farmed salmon in order objectively to assess the sustainability of this industry in this regard. Using updated information regarding domestic aquafeeds this review reports advances that have been made in diet formulation, fish in-fish out (FIFO) and feed conversion ratios (FCR) and demonstrates that production efficiency of farmed salmonids has significantly improved over time due to continued innovations in the aquafeed sector. The results suggest that the Canadian salmon aquaculture industry efficiently converts wild fish resources into highvalue fish products.