TABLE 5. Juraszs' vessel/aircraft classes (after Jurasz and Jurasz, 1979)
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Class 16 R/V GINJUR (Juraszs' research vessel)
The increase in visitors and vessels to Glacier Bay is presented in Tables 6-8. (Data included in Table 6 cannot be compared to data presented in Table 7 because of difference in methods of data collection, sample area, time, effort, etc.)
Commercial fishing vessel activity in the Bay was probably low until the 1970's. Since 1972 (it is not known whether data are available prior to 1972) commercial fishing vessel visits have fluctuated (Figure 4), but fishing activity has been greatest during the summer months (Figure 5). Sport fishing visits have increased during the same time period (Figure 6).
[Footnote 4: This summary is based on information presented at the meeting by Mr. John Chapman and Charles and Virginia Jurasz.]
POSSIBLE CAUSE-EFFECT RELATIONSHIPS BETWEEN HUMAN USE OF GLACIER BAY AND THE DISPLACEMENT OF HUMPBACK WHALES FROM THE BAY[5]
The meeting participants agreed that the observed decrease in the number of whales in Lynn Canal in 1974 and Glacier Bay in 1978 may be attributable to a number or combination of factors. Available evidence suggests human activity was at least one of the causes, or served to trigger otherwise "natural events". In Lynn Canal, humpback whales were known to feed on herring (_Clupea harengus pallasi_). In 1974, the year a herring fishery began, the number of humpback whales dropped to one (Table 1). Between 1974 and 1978 fishing continued. There was no fishing in 1979.
Use of the Canal by Class 5 vessels (cabin cruisers with high RPM outdrive units) increased by 15-20 percent each year after 1970 (Jurasz and Jurasz, 1979, p. 85). Three humpback whales were seen in Lynn Canal during the 1975-1977 seasons, the number increasing to five in 1978-1979. The relationship between vessel activity, fishing effort, fish take, fish abundance, and the presence and activity of whales in Lynn Canal does not appear to be documented.
In Glacier Bay, increased vessel traffic may be one of the factors responsible for the movement of humpback whales from the Bay in 1978 and 1979. The Juraszs' data, while not evaluated fully, suggest that there has been a general increase in avoidance by humpback whales of Class 1 through 5 vessels over the three year period, 1976-1978.