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Observations of feeding and ventilatory behavior of individual fin whales (Balaenoptera physalus) were made from various vessels during the months of May - September, 1981-87, in the waters off eastern Long Island, N.Y., U.S.A.. Intervals between blows were measured and recorded to the nearest second. Information about behavior was recorded, as were location, depth, and surface temperature at sounding dives. Animals observed feeding at the surface were noted as such, all others were considered non-surface feeding. Data were compiled by individual, month, year, and analyzed for mean interblow interval during surface activity bouts; mean dive duration; and overall mean blow interval.
Overall mean blow intervals (± s.e.) of 47.89 ± 0.81s for feeding (n = 10411), and 57.92 ± 0.97s for non-surface feeding animals (n = 11024), differed significantly (Mann-Whitney U, p < .001). Interblow intervals for surface activity bouts (± s.e.) of 12.29 ± 0.05s for feeding (n = 7894), and 13.58 ± 0.06s, for non-surface feeding animals (n = 8187), also differed significantly (Mann-Whitney U, p < .001), as did mean dive duration (159.53 ± 2.16s, n = 2517, for feeding animals; 185.86 ± 2.53s, n = 2837, for non-surface feeding animals). Yearly comparisons of blow intervals between feeding and non-surface feeding animals during surface activity bouts yielded significant differences for each year except 1981, while comparisons of dive durations yielded significant differences for all years except 1981, 1982, and 1985.
(1, 2, 4) Long Island University, Southampton College, (3, 5) Coastal Research and Education Society of Long Island, Inc.
Surveys of fin whales, (Balaenoptera physalus) were conducted during the months of May through September, from 1979 through 1996, off Long Island, New York. Surveys primarily occurred aboard whale watching vessels. When possible, individual identification photographs were collected on the cruises. Photographs from 1981 through 1988 were compared for matches of individuals based upon the technique described by Agler et al. All identification type photographs were entered into a computer database to facilitate a more rapid matching of individuals. Animals were keyed into the database based upon dorsal fin type, chevron, and/or nicks and scars. Initial matching was based upon these features. Final matches were made by manually examining each slide and matching at least 5 major features for each whale.
Individual fin whales were found to occupy the region on a recurring basis over numerous years. In some instances occupancy was repetitive on an annual basis, while in other instances gaps of one or more years occurred. Individual fin whales were found to occupy the region for a period of up to 9 weeks, however, many animals were not photographed on a continuous or daily basis. This may not be indicative of movement from the area as surveys throughout the entire occupancy area were often not possible aboard the platform vessel. Residency diagrams presented with this study demonstrated a clear preference to return to the region over a period of years.
In 1987, a very large number of new animals were seen in the area, as some of the largest numbers of whales found in the region were observed. In our analysis, this year had to be considered anomalous based upon the extremely large number of whales found in the region. The large number of whales seen has not been repeated since that time.
The resighting rate indicates that a significant number of animals seen annually in the region were previously sighted individuals. Based upon the high resighting rate and the long term annual recurrence of individual fin whales, this area may be a significant seasonal residency site. However, animals were not always seen in the same areas either within one year or over a period of years. Resightings of whales indicate a use of the whole area and not a specific trend to one site. Consequently, movement throughout the area would be expected based upon our analysis.