SWFSC Cetacean Sightings in the Eastern Tropical Pacific (1508)
NOAA Southwest Fisheries Science Center (SWFSC)

N/A

This 1993 line-transect survey was designed to make abundance estimates of the northern stock of common dolphin, Delphinus delphis, in the eastern Pacific. This stock of dolphin is taken in the tropical tuna fishery. The index of relative abundance for this stock, computed from sightings on tuna vessels, has declined substantially in the last decade. However, because tuna vessels cover only the southern portion of the stock's range, the declines in the index may be due to a northward shift in distribution, rather than an actual decline in abundance. The 1993 survey was designed to produce the first range-wide estimates of abundance for the northern common dolphin and its recently described congener, Delphinus capensis. This survey was conducted by the NOAA Southwest Fisheries Science Center aboard NOAA Ships McArthur and David Starr Jordan for a combined total of approximately 32,000 kilometers surveyed from late July to early November 1993. This dataset provides the time-date and geographical coordinates, by species/stock, of all cetaceans detected during the survey, as well as the daily and intra-daily start and end points of the line-transect survey.

The primary objective of the cruise was to survey the area inhabited by the northern stock of common dolphins, and to make an estimate of its absolute abundance in order to assess the impact of the dolphins killed by the United States and international yellowfin tuna purse seine fleet in the eastern tropical Pacific.

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Mangels, K.F., and T. Gerrodette. 1994. Report on cetacean sightings during a marine mammal survey in the Eastern Tropical Pacific Ocean aboard the NOAA Ships McArthur and David Starr Jordan, July 28-November 6, 1993. NOAA-TM-NMFS-SWFSC-211

Overview

Attributes described below represent those in the original dataset provided by the provider.
Only minimum required attributes are visible and downlodable online. Other attributes may be obtained upon provider's permission unless otherwise noteded below.

Attributes in dataset provided

Attribute (table column)	Description
dataset
lineno
cruise
date
time
sightno
spcode
scientific
scientific
common
tsn
latitude
longitude
school
excluded
oid