SWFSC Marine Mammal Survey, PODS 1993, Cruise 1508

NOAA Southwest Fisheries Science Center (SWFSC)

Dataset credit

NOAA Southwest Fisheries Science Center (SWFSC)


Primary contact Jeffrey Moore Southwest Fisheries Science Center, NOAA
Data entry Benjamin Best Duke University



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 by the NOAA Ship McArthur.


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.

Supplemental information

[2021-04-12] Updated with additional attributes.

SWFSC MMTD Cruise Number: 1508
Perpendicular distance will be released upon permission by the contributor. Please contact the contributor if needed.

Attribute descriptions for effort data:
dist: Length of the segment (km)
Mode: Effort mode type (C = closing mode; P = passing mode)




This section explains attributes included in the original dataset. OBIS-SEAMAP restricts the attributes available to the public to date/time, lat/lon and species names/counts only. Should you need other attributes described here, you are encouraged to contact the data provider.

Attributes described below represent those in the original dataset provided by the provider.
All attributes are included in the downloadable file (CSV or ESRI File Geodatabase) for "Complete Set of Dataset".

Attributes in dataset

Attribute (table column)Description
oidUnique ID number (generated by OBIS-SEAMAP)
eventEvent code. S = cetacean sighting, t = sea turtle sighting, p = pinniped sighting
datetimeDate and time of sighting (local time)
latLatitude (decimal degrees) of vessel when sighting was made
lonLongitude (decimal degrees) of vessel when sighting was made
cruiseSWFSC Marine Mammal and Turtle Divison Cruise number
sightnoSighting number (within Cruise)
nspNumber of species observed in the sighting
mixedTRUE for a multi-species sighting (nSp >= 2); FALSE otherwise (nSp = 1)
spcodeSpecies code
sp_tsnTaxonomic Serial Number added by OBIS-SEAMAP
gsspbestThe mean of all observers
gssphighThe mean of all observers
gssplowThe mean of all observers
perpdistkmPerpendicular distance (km) to sighting from trackline; Available upon permission.
bftBeaufort sea state, as assessed by looking upswell with the naked eye
swellhghtAverage swell height from trough to crest of typical swells (estimated in feet, by eye)
visA measure of air/atmospheric clarity only, as affected by observational conditions such as fog, rain, etc.
groupsize_sightnoRunning count ID of all cetacean groups recorded
groupsize_countNumber of observers that provided a group size estimate
groupsize_count_obsNumber of unique observer codes per sighting for S events
geomGeometry field added by OBIS-SEAMAP
Marine mammals635
Sea turtles17
Rays and sharks0
Other species0
Non spatial0
Non species0
Date, Begin1993-07-28
Date, End1993-11-02
Temporal prec.111111
Latitude21.03 - 41.94
Longitude-130.64 - -106.97
Coord. prec.6 decimal digits
Data typeAnimal sighting
EffortYES (ID: 214)
Traveled (km)8,649
Effort hours460
Contr. through
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