Marine Fisheries Review 2010: Vol 72 Iss 4

2010·14.8 MB·English

“>, Marine Fisheries
od.
ct Y~e~
s
Tares OF
Deep-Water Fishes and Invertebrates
of the U.S. Gulf of Mexico
Marine Fisheries
YT
W. L. Hobart, Editor
wy,
J. A. Strader, Managing Editor SS >
“
Evy Siga
On the cover:
en ater fishes and invertebrates of the U.S. Gulf of Mexico.
*hotos by Dean Landi (formerly with NMFS Mississippi Labora-
tories), Brandi Noble of NMFS Mississippi Laboratories, and from re
the NMFS Mississippi Laboratories deep-water fishes photo ae Pera
archive. A species list for the cover is at the bottom of the page bh
72(4), 2010
Articles
Forty Years of Winter: Cetaceans Observed
During the Southbound Migration of Gray Whales,
Eschrichtius robustus, Near Granite Canyon, Central California Kim E. W. Sheldon and David J. Rugh
Fishery-independent Bottom
Trawl Surveys for Deep-water Fishes and Mark A. Grace, Brandi Noble, Walter Ingram,
Invertebrates of the U.S. Gulf of Mexico, 2002-08 Adam Pollack, and Alonzo Hamilton.
Soft Flesh in Sablefish, Anoplopoma fimbria, of Southeastern John F- Karinen, Harold J. Barnett,
Alaska: Relationships with Depth, Season, and Biochemistry and Michelle Masuda
Annual Index and List of Papers
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Cover photographs:
Left vertical row from top down: Trachurus lathami (rough scad), Macroramphosus gracilis (slender snipefish),
Halieutichthys aculeatus (pancake batfish), Hydrolagus alberti (chimera). Center vertical row from top down:
Loligo pealei (longtin inshore squid), Zenopsis conchifera (buckler dory), Astronesthes similis (family Stomiidae,
dragonfishes), Siratus beauii (murex). Right vertical row from top down: Antennarius radiosus (singlespot
frogtish), Mesopeneaus tropicalis (salmon shrimp), Platylambrus granulatus (bladetooth elbow crab),
Acanthaxius hirsutimanus (family Axiidae, lobster shrimps), Plesionika edwardsii (soldier striped shrimp).
Forty Years of Winter: Cetaceans Observed During the Southbound
Migration of Gray Whales, Eschrichtius robustus,
Near Granite Canyon, Central California
KIM E.W. SHELDEN and DAVID J. RUGH
Introduction From 1967 to 2007, 25 censuses of but because the gray whale sightings
southbound migrating gray whales, have been thoroughly documented
The coastal waters of central Cali- Eschrichtius robustus, were conducted elsewhere (Shelden et al., 2004; Laake
fornia provide foraging habitat and in winter (primarily mid-December to et al., 2009), this species is not included
migration corridors for a variety of tem- mid-February) at shore-based stations in this report.
perate and warm-water cetacean taxa. just south of Carmel, Calif. (Reilly et Historically there has been little
In Monterey Bay and south of Carmel, al., 1983; Rugh et al., 2001; Shelden et dedicated survey effort documenting
deep submarine canyons penetrate the al., 2004). Gray whales were the target cetaceans off central California during
continental shelf, in some places reach- species for the census; therefore, the the winter months of December through
ing within meters of shore (Greene et al., study was timed to include virtually all February. We are aware of only two
2002). The continental shelf narrows to of their southbound migration. studies. The first, a pelagic fur seal
within 4 km of shore south of Carmel During these gray whale surveys, study, during which cetacean sightings
Bay then fans out seaward to roughly 15 observers also recorded the presence were recorded incidentally, occurred
km off Point Sur (Fig. 1).T he variety of of other cetacean species. We exam- in 1958, 1959, and 1961 (Fiscus and
bathymetric features provides a unique ined these shore-based records and Niggol, 1965), which was before the first
region where pelagic and coastal species observations obtained during aerial censouf sgra y whales in central Califor-
intermingle. surveys in January 1988, 1993, 1994, nia. The second study (Dohl et al.') oc-
and 1996 (Shelden and Laake, 2002), curred during a period (1980-83) which
to document cetacean occurrence in coincided with years when the gray
Kim E.W. Shelden ([email protected]) winter off this portion of the central whale census was not in operation. The
and David J. Rugh are with the National Marine California coast. Our objective here results of those two studies are included
Mammal Laboratory, Alaska Fisheries Sci
is to describe which cetaceans are in this review.
ence Center, National Marine Fisheries Service,
NOAA, 7600 Sand Point Way N.E., Seattle, WA within the study area during winter,
98115-6349. Methods
The study area for our review in-
cludes waters between Carmel 3 ay
and Point Sur, Calif., extending from
ABSTRACT— From December to Feb- whale, Megaptera novaeangliae; minke
the coast to roughly 37 km (20 n.mi.)
ruary in most years from 1967 to 2007, whale, Balaenoptera acutorostrata; and
observers counted gray whales, Eschrich- blue whale, Balaenoptera musculus). As offshore (Fig. | box). Near the research
tius robustus, from shore sites south of expected, the detection of certain species sites used to count gray whales (Yankee
Carmel in central California. In addition among survey platforms (shore-based
to gray whales, other cetacean species census watches, 25-power “Big Eye” bin
were also recorded. These observations ocular watches, and aerial surveys) was
were summarized and compared among limited by species surfacing behavior and
Dohl, T. P.. R. C. Guess, M. L. Duman, and R
survey platforms and to ocean conditions. or bathymetric preference. Comparisons C. Helm. 1983. Cetaceanso f central and northern
Eleven cetacean species were identified among the shore-based census efforts California, 1980-1983 status, abundance, and
including eight odontocete species (killer showed a significant difference in sight distribution. Final Rep. Minerals Manage. Serv
whale, Orcinus orca; Pacific white-sided ings rates from 1967-84 (n 14, mean Contr. 14-12-0001-29090 prep. by Cent. Mar
dolphin, Lagenorhynchus — obliquidens; = 0.11, SD = 0.11) to 1985-2007 (n Sci., Univ. Calif., Santa Cruz. OCS Study MMS
common dolphin, Delphinus spp.; bottle- 11, mean = 1.48, SD = 047; t-Test: p < 84-0045, 284 p
nose dolphin, Tursiops truncatus, northern 0.001,d f = 23). The warm period observed Dohl, T. P.,M . I Bonnell, R. ( Guess, and K
right whale dolphin, Lissodelphis borea- during the 1990’s may partially explain lr. Briggs. 1983 Marine mammals and seabirds
lis; Risso’s dolphin, Grampus_ griseus; the increase in sighting rates and diversity osfy ntcheenstirsal oafn d fniondritnhgesr.n CFailniaflo rniRae p. 198M0i-n1e9r8a3ls
Dall’s porpoise, Phocoenoides dalli; and of species observed at the census site com- Manage. Serv. Contr. 14-12-0001-29090 prep. by
harbor porpoise, Phocoena_ phocoena) pared to the much cooler temperatures of Cent. Mar. Sci., Univ. Calif., Santa Cruz. OCS
and three mysticete species (humpback the 1970's. Study MMS 84-0042, 248 p
Point’ and Granite Canyon’), the shelf
123°W
extends 4.2 km (2.25 n.mi.) offshore
where it rapidly descends from 140 m
to 200 m within 0.37 km (0.2 n.mi.). For mail” ~~ Nh
all datasets, we limited the analysis of
sightings to the months of December, San Francisco /
January, and February \ Bay \ Tye
a X A Laat
Survey Datasets Point = aes!
Conception a) 7
Vessel Surveys 1958-61
°P r San Francisco Bay
Vessel surveys were conducted in o
the waters between Point Reyes (near
San Francisco Bay) and Point Sur in
1958 (1 Feb—10 Apr.), 19(5209 Ja n.—8
Apr.), and 1961 (5-15 Jan. and 16 Pacific
Feb.—1 Apr.) (Fiscus and Niggol, 1965). Ocean
Monterey Bay
Effort during these vessel surveys was
focused from the 100 fathom (fm) curve
Carmel Bay
(183 m isobath) to 185 km (100 n.mi.)
offshore. Watches occurred from 0600
to 1800 h daily, and the vessel left the Point Sur
Study
trackline to confirm cetacean sighting
identifications only when seals were Area
not present. Unidentified cetaceans were
not recorded. Sighting and catch data
presented in tables and text in Fiscus
and Niggol (1965) were entered into
an MSExcel? spreadsheet and imported
into ArcView (ESRI) to determine
which fell within the boundary of the
study area. Unfortunately, it was not
possible for us to determine the amount 90 180
of effort or where survey tracklines oc-
curred within the study area based on Kilometers oint Conception| ~
0 50 100
the figures and descriptions provided in
idatiaienaeennnaall
Fiscus and Niggol (1965). Nautical Miles
123°W 122°W 121°W 120°W
Shore-based Census 1967-80
Figure |.—Study area (box) showing place names mentioned in the text.
Systematic shore-based censuses of
the southbound gray whale migration
began in 1967 at Yankee Point (lat. 36° and details on sighting time and loca-
29’30’’N) at a site 23 m above sea level. tion. Sighting effort was calculated for
Yankee Point is a residential area A house with
in excellent view of the sea was made available In 1974, the census site was moved a entire watch periods as portions of a
tor documenting the gray whale migration from few kilometers farther south to Granite day (24 h) where average visibility was
196t7o 1974 : Canyon (lat. 36° 26’41”N), to the edge <4 (all but “poor” or “useless” view-
Granite Canyon is a research station owned by
of a cliff 21 m above sea level (Fig. 2). ing conditions) and Beaufort was <4
NOAA since the mid 1960's. The site has been
used by California Department of Fish and Game During watches, single observers rotated (sea state calmer than when there are
for aquaculture research, University of Califor on 5-h shifts throughout all daylight moderate waves with many whitecaps;
nia (UC) Davis for water pollution/quality stud
es. and a consortium including UC Santa Cruz, hours (0700 to 1700 h), conducting inde- <30 km/h). Distances of the animals
the Naval Postgraduate School, and Cal State pendent searches across a 150° viewing from shore were estimated during this
University Monterey Bay to monitor ocean cur
rents with high frequency radar (http://www area (Reilly et al., 1983). period without any calibrations, so they
envtox.ucdavis.edu/GraniteCanyon/SettingHis Records included effort (start and are not considered reliable. Therefore,
tory.html) stop time of systematic searches), sighting locations could not be mapped
Reference to trade names or commercial firms environmental conditions (visibility, in ArcView. Instead, these sightings are
does not imply endorsement by the National
Beaufort sea state, and wind direction), presented in tabular form. It appears that
Marine Fisheries Service, NOAA
Marine Fisheries Review
he at
x te‘ nagg 4 linPgiek ieegra gll ian=c e teams Swo" e - es ee "aetna
= tRee e
ae a ae .
Figure 2.—A view from sea level of the Granite Canyon research site 13 km south of Carmel in central
California. This is the site from which gray whale counts have been conducted most winters 1967-2007.
the data forms and sighting protocol re- lines fell within our study area. Sighting or offshore from the descriptions and
mained the same throughout this period. data for the south-central sector, which figures provided in Dohl et al.'~
Although for the 1978-79 census, a included waters between Point Sur (lat.
new data form and accompanying in- 36° 20’ N) and Russian River (lat. 38° Shore-Based Census 1984—2007
structions were introduced to ease key 30° N), were kindly provided by Bonnell After a 4-yr hiatus, gray whale census
punching the hand-written data, field and Ford®, after accessing the Dohl da- operations resumed once again in the
methodology did not change. tabase through OBIS-SEAMAP (Read winter of 1984-85. During this census,
etal.’). Similar to the Fiscus and Niggol the same methods used during the ear-
Aerial Surveys 1980-83
(1965) dataset, sightings were imported lier censuses were followed to allow
Low (60 m = 250 ft) and high (300 m into ArcView to determine whether any for inter-year trend analysis (Dahlheim
= 1,000 ft) altitude aerial surveys were fell within the study area. Unfortunately, and Rugh®), and the same data form and
flown bi-weekly to document marine we could not determine how often instructions were used from 1979 to
mammals and seabirds in the waters survey tracklines were flown in the study 1988. However, some adaptations have
off central and northern California from area or ift he segment flown was coastal been made through the years:
1980 to 1983 (Dohl et al.'*). The project
was undertaken to provide data to the *Bonnell, M. L., and R. G. Ford. 2001. Marine 1) Beginning with the 1985-86
Pacific Outer Continental Shelf (OCS) msyasmtmema.l MaMnSd -sCeaDbAirSd cVoemrpsuitone r 2.d1a. taCbDa seR OaMna lypsries- census, observers rotated on
Region of the Minerals Management pared by Ecological Consulting, Portland, Oreg., three shifts covering 10 daylight
Service in regard to oil and gas lease for the Pacific OCS Region, Minerals Manage. hours per day (3.5 h, 3 h, and
Serv., Order No. 14-12-001-30183.
areas. East-west tracklines (92 in all)
’Read, A. J., P. N. Halpin, L. B. Crowder, K. D.
extended from shore out approximately Hyrenbach, B. D. Best, E. Fujioka, and M. S. ‘Dahlheim, M. E., and D. J. Rugh. 1991. A his-
175 km and were broken into coastal Coyne (Editors). 2006. OBIS-SEAMAP: map- torical review of censusing gray whales. Unpubl.
(0-99 fm) and offshore (100-999 fm) ping marine mammals, birds and turtles. World pap. presented to the Scientific Committee of the
Wide Web electronic publication. Accessed 24 International Whaling Commission, SC/A90/G4,
segments. Of these, 3 of the 92 track- May 2006 [http://seamap.env.duke.edu]. 8 p.
3.5 h) instead of only two shifts All cetacean sighting (other than “Big Eye” Watches 1992-2007
(each 5 h), and after 1993, each gray whales) were entered into an Excel
Watches conducted with 25x “Big
of the three watches was 3 h, spreadsheet. Unidentified cetaceans
Eye” binoculars started in December
covering 9 h per day were reclassified to species only ift ime, 1992 at Granite Canyon (Rugh et al.,
In January of each year since location, and descriptions were similar
2002). Thereafter, “Big Eye” watches
1985, part of the census opera- between the paired records when only occurred every Januarya,nd in 2001 and
tion included concurrent, inde- one of the observers provided a species
2002 the watches extended into Febru-
pendent watches (Rugh et al., identification. Sighting effort was lim-
ary. Paired, independent searches for
1990). For our analysis, cetacean ited to daily effort values in portions of
gray whales were conducted through fix-
sighting records from these con- a day (24 h) when the average visibility mounted “Big Eye” binoculars during
current watches (South Shed and was <4 and Beaufort was <4. For data
6-25 Jan. 1995 and 7—25 Jan. 1996. The
North Shed: Fig. 3) were con- prior to 1987, the exclusion of effort
“Big Eye” study was a test of an efficient
sidered separate sightings when was for a whole 5-h watch period at a
method for documenting inter-year
both observers recorded the same time because changes in environmental changes in the offshore distribution of
species at about the same time conditions were not indicated except
the migration. Similar to the concurrent,
and location because the efforts when sightings occurred. From 1987
independent shore-based census effort,
were completely independent. onward, the data protocol included an
the South “Big Eye” Shed and North
Since 1987, magnetic compasses independent code indicating when vis-
“Big Eye” Shed (Fig. 4) were considered
and vertical reticle marks in ibility or weather changed. This made
separate sightings when both observers
handheld 7x50 binoculars pro- it possible to exclude select portions of
recorded the same species at about the
vided data on sighting locations waich periods from the analysis.
same time and location because the ef-
(Rugh et al., 1990). The focus forts were completely independent. As
of the sighting effort was along Aerial Surveys 1988—96
with the shore-based sightings, location
a line perpendicular to the coast- Cetacean sightings were also docu-
and distance offshore for each “Big Eye”
line, at 241° magnetic. mented during aerial surveys conducted
sighting was calculated using NewPo-
concurrent te censuses in January 1988,
sLon, NewPosLat, and RetDistBE’, re-
Cetacean sighting locations (lati- 1993, 1994, and 1996 (Shelden and
spectively, and imported into ArcView.
tude and longitude) were determined Laake, 2002). These aerial surveys
using the compass bearing and reticle were designed to characterize the oft- Oceanography
provided at the time of the sighting, shore distribution of gray whales by Where data were available, oceano-
and altitude and location (latitude and flying tracklines perpendicular to the
graphic parameters were included with
longitude) of the survey shed (New- shore in the vicinity of the station at
each sighting. Daily surface water
PosLat and NewPosLon functions for Granite Canyon. Earlier aerial surveys
temperatures were obtained from the
Excel’). Distances to sightings were conducted in January 1973 (Sund and
Scripps Institution of Oceanography
calculated using the RetDist7x50 func- O’Connor, 1974) and during the 1978—
(SIO) Shore Station Program website!”
tion in Excel.’ The sightings were then 79 and 1979-80 censuses (Reilly et al.,
for waters at the Granite Canyon station.
plotted in ArcView and joined to near- 1983), also designed to characterize the
Because temperatures were available
est sounding in National Oceanic and gray whale migration corridor, did not
only since 1971 at Granite Canyon,
Atmospheric Administration (NOAA) report cetacean sightings other than gray we explored using other sites such as
electronic nautical charts (ENC). whales. Therefore, only the 1988-96
Pacific Grove (near Monterey Bay) as
In most census years, any cetacean surveys are used here. 2 proxy for the earliest census years:
sighting other than a gray whale wa: Cetacean sighting locations during
1967 to 1970; however, the available
treated as a comment entry in the da- aerial surveys were obtained by inter- data were not compatible when records
labase. Starting in December 1987, polating distances from shore relative
were kept at both sites (t-Test, p= 0.046,
data forms were modified to include a to time of sighting on the trackline (i.e. df = 187). Am onthly surface water tem-
behavioral code for gray whales asso- dead-reckoning) or, beginning in 1994,
perature anomaly was calculated as the
otiier Species, but all other using global positioning system (GPS)
4 iaied with difference between the average monthly
cetacean sightings were still entered as location data (Shelden and Laake,
temperatures for a given month and the
comments. In December 2001, a dedi- 2002). These sighting locations were
long-term mean temperature for the
cated code was introduced on the data imported into ArcView. Sighting dis-
calendar month from 1971 to 2007 for
form to identify all other cetaceans. tances were compared among the three
Granite Canyon. Anomalies were then
datasets: shore watch, aerial surveys,
and 25x “Big Eye” binocular watches
Maiine Maninial Labvuiatory. Soft (presented in the next section) for each 'SScripps Institution of Oceanography (SIO)
Excel Geometry Functions Available at January when all three studies were in Shore Station Program website. Accessed 24
v.afsc .noaa.gov/nmimi/software/excel April 2007 [http://shorestation.ucsd.edu/data
operation. index_data.html ].
Marine Fisheries Review
Horizon
cbA aa
.i:
Aii te} vai a) m se oT
Oe
i)
aM 3y :
Figure 3.—Schematic of observation sheds and sighting protocol used to count gray whales durin g the gray whale southbound
migration past Granite Canyon.
normalized by dividing by the standard 1991). Daily upwelling indices were ob- 49 km southwest of Granite ‘ ‘any on)
deviation of the long-term mean for each tained from the Pacific Fisheries Envi- monthly upweiling index (UI) anomaly
month. Monthly sea surface temperature ronmental Laboratory!', NOAA. Indices was calculated using the technique de-
(SST) anomaly data were then linked to were available for all census years (1967 scribed for the SST data
each sighting. to 2007) from a site at lat. 36° N, 122 In addition to these shorter-scale
Plankton productivity is strongly tied W (33 km southwest of Point Sur and oceanic variables, comparisons were
to the upwelling of cold, nutrient-rich made to climate regime shifts in the
sub-surface waters. In particular, wind- North Pacific (Mantuae t al., 1997; Hare
''Pacific Fisheries Environmental Labcratory
induced coastal upwelling in which the and Mantua, 2000). Shifts stgnifieant
website. Accessed 24 April 2007 [http WWW
upward movement is a consequence of pfeg.noaa.gov/products/PFEL/modeled/indi enough to have potentially affected
wind stress (along shore) and Ekman ces/upwelling/NA baety down ioad.html;ftp gray whale abundance estimates ate
orpheus.pfeg.noaa. gov/outgoing/upwell/daily
transport (offshore) ( Bakun and Nelson, plOdayac.all]. purported to have occurred in 1976-77
Figure 4 Photograph of sheds used to house two 25x “Big Eye” binoculars at Graiite Canyon. The paired, independent effort
through these two binoculars provided a test of sighting rates.
and 1988-89 (Hare and Mantua, 2000: migrated beyond the visual range of whales and 90 percent of the smaller
Benson and Trites, 2002). observers on shore (Rice and Wolman, cetaceans seen could be identified.”
1971). This was confirmed in January Cetacean sightings reported in the
Results and Discussion
1973, when five flights were conducted waters between Carmel Bay and Point
Because gray whale results are to test the width of the migration corri- Sur in January and February during
reported elsewhere (e.g. Shelden and dor (Sund and O’Connor, 1974). Results these vessel-based surveys included
Laake, 2002: Rugh et al., 2005; Laake indicated that 96% of the whales passed gray whales (one sighting of two whales
et al., 2009), this species is not empha- within 4.8 km (2.6 n.mi.) of shore (94% on 28 Jan. 1959) and two odontocete
sized here. In every year of the census, within 1.6 km). This offshore distribu- species: Pacific white-sided dolphins,
gray whales were seen in great numbers tion was also documented during aerial Lagenorhynchus obliquidens ,a nd Dall’s
(from 657 to 2,853 sightings per year; surveys near the Granite Canyon station, porpoise, Phocoenoides dalli (Fig. 5).
mean = | 564 sightings, SD 514). These where fewer than 2% of the whales Group sizes for Pacific white-sided dol-
whales were seen on almost every day migrated beyond the sighting range of phins ranged from 4 to over 100 while
of each of the 25 censuses, sometimes shore-based observers (Shelden and Dall’s porpoise group sizes ranged from
with >100 sightings per day. The peak of Laake, 2002). The census periods and 4 to 8. All odontocete sightings occurred
the migration occurs in mid January, and sighting effort for the shore-based in February.
90% of the sightings occur in January census are presented in Table 1.
(Rugh et al., 2001). Shore-Based Census 1967-80
Vessel Surveys 1958-61
During whale marking cruises con- During this period from 1967 to
ducted near Yankee Point in the 1960's, According to Fiscus and Niggol 1980 when the gray whale census was
=
it was determined that few gray whales (1965), “about 50 percent of the large underway, there were 22 sightings of
=
Marine Fisheries Review
Figure 5.—Cetaceans observed near Granite 122°20'W 122°W
Canyon during pelagic fur seal vessel sur-
veys Dec.—Feb. 1959 and 1961 (Fiscus and
&
Niggol, 1965). Symbols denote gray whales
(circle), Pacific white-sided dolphins (tri-
angle), and Dall’s porpoise (square).
cetaceans other than gray whales (Table Pup
‘
1). Of these, on average, roughly 30%
¢*ankee
were identified to species (Table 2)
' Point
which included Pacific white-sided
?
dolphins; killer whales, Orcinus orca;
and humpback whales, Megaptera no- Granite
Canyon
vaeangliae. If an observer’s comment
indicated he/she was not fully confident
of the species identificationt,h e sighting
was not identified to species nor used
in subsequent analyses (see footnotes |
and 2 in Table 2). All useable sightings
were recorded in the month of January,
with the exception of a sighting of a J 4
Pacific white-sided dolphin in February 100 m depth intervals 10 m/depth intervals Point Sur
1968. Unidentified dolphin and whale 122°10'W 122°W 121°50'W
sightings were also recorded most often
in January (nine sightings and two 8 10 12 14 —-16 18 20 22
SS —x———— ee N
sightings, respectively). We did expect Nautical Miles }
a focal species bias particularly when 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 \
the bulk of the gray whale migration a I I a Kilometers ———= \
was passing the counting stations in
January. However, there is no evidence
in these data that gray whale sightings Tabie 1.—Number of cetacean sightings (other than gray whales and including unidentified cetaceans) reported off
central California during the winter census of gray whales by observers on shore watch. Effort days (24 h) repre-
significantly eclipsed records of other sent when average visibility was = 4 and Beaufort sea state was < 4 for the period December-February. The move
cetaceans. from the Yankee Point counting site to Granite Canyon occurred after the 1973-74 census. Gaps between census
years indicate when the census was not in operation
Aerial Surveys 1980-83 Census sites and dates
Aerial surveys of the waters between 18 Dec 1967—4 Feb 1968
10 Dec 1968-7 Feb 1969
Carmel Bay and Point Sur documented
8 Dec 1969-9 Feb 1970
six odontocete species during the win- 9 Dec 1970-13 Feb 1971
ters of 1980-83 (Fig. 6). The thirteen 18 Dec 1971-8 Feb 1972
16 Dec 1972-17 Feb 1973
sightings included Pacific white-sided 14 Dec 1973-9 Feb 1974
dolphins; Dall’s porpoise; killer whales; 10 Dec 1974-7 Feb 1975
Risso’s dolphins, Grampus griseus; 10 Dec 1975-4 Feb 1976
10 Dec 1976-7 Feb 1977
northern right whale dolphins, Lisso-
10 Dec 1977-5 Feb 1978
delphis borealis; and harbor porpoise, 10 Dec 1978-9 Feb 1979
10 Dec 1979-7 Feb 1980
Phocoena phocoena (Table 3). A
28 Dec 1984-7 Feb 1985
mixed-school of Risso’s dolphins and
10 Dec 1985-7 Feb 1986
northern right whale dolphins was ob-
10 Dec 1987-7 Feb 1988
served on 6 Jan. 1981 (Table 3, Fig. 6).
10 Dec 1992-7 Feb 1993
Sightings were reported in every winter 10 Dec 1993-17 Feb 1994
month only during 1980-81; however, 6-26 Jan 1995
10 Dec 1995-23 Feb 1996
we do not know if flights occurred in
9-23 Jan 1997
January 1982 or February 1983 in the 13 Dec 1997-24 Feb 1998
study area. We suspect that most of 13 Dec 2000-5 Mar 2001
these tracklines were well offshore 12 Dec 2001-5 Mar 2002
(100-999 fm) given the absence of gray 12 Dec 2006-22 Feb 2007
whale sightings. Total
Shore-Based Census 1984—2007 were recording any cetacean they saw. Pacific white-sided dolphins, Dall’s por-
It was just that cetaceans other than gray poise, killer whales, Risso’s dolphins,
Non gray whale cetacean sighting whales “were few and far between” in northern right whale dolphins, harbor
rates increased significantly after 1984 those early years of the census (Rice!*). porpoise, and humpback whales. A little
(Table 1). Although there were some Comparisons among the primary sight- over half (on average 57%) of all odon-
minor methodological changes made ing efforts show a significant difference tocete sightings reported by shore-based
during the 1985-86 census, they do in sightings rates from 1967-84 (n= 14, observers were identified to species
not account for such a dramatic change mean = 0.11, SD =0.11) to 1985-2007 compared to 71% of mysticete sightings
in sighting rates. The data forms and (n= 11,mean= 1.48,SD =0.47; t-Test: (Table 5). Dall’s porpoise, harbor por-
instructions used in 1985-86 were first p<0.001, df= 23). Within-season com- poise, and northern right whale dolphins
used during the 1979-80 census. The parisons showed good agreement, in that were rarely observed from shore (Table
only changes to survey methods were sighting rates between the paired sheds 5). These species are found year-round
including paired, independent effort (Table 4) were not significantly different off the central California coast (Leather-
during January, reducing the length of (t-Test: p = 0.58, df = 18). wood et al., 1982; Forney, 1997; Chivers
watch periods, and providing vertical Eleven species were identified during et al., 2002). Dall’s porpoise can be very
and horizontal data on each sighting. the latter halfo f the census years, since visible when “rooster tailing,” but group
These changes are not thought to have 1985 (Table 5), including seven spe- sizes were small. Smail group sizes and
raised or lowered the probability of cies reported during the earlier studies: low surfacing profile also made detec-
recording sightings. tion of northern right whale dolphins and
\fter comparing observers and sight- Rice, Dale, Gray Whale Census Project Leader harbor porpoise difficult, and northern
ing records from the earliest years of the 1967-1980. National Marine Mammal Labora right whale dolphins were only observed
tory, NOAA, NMFS, Seattle, Wash. Personal
census, we determined that observers commun. 23 April 2007 in mixed-species groups.
Three species (Risso’s dolphins;
common dolphins, Delphinus spp.:;
122°20'W 122°10°'W and bottlenose dolphins, Tursiops
truncatus) Were first recorded by the
census teams during the 1980’s. Two
separate species of common dolphins
occur off central California (Heyning
and Perrin, 1994; Benson et al., 2002):
long-beaked, Delphinus capensis, and
short-beaked, D. delphis. However, ob-
servers did not report common dolphins
gYankee
to the species level. Bottlenose dolphins
; Point 7
were also seen north and south of the
gray whale census study site in Decem-
vi nite ber 1984, January 1985, and December
“canyon 1986, during periods when the census
36°20'N /
was not in operation (Wells et al., 1990).
Our first sighting of bottlenose dolphins
(a group of 15 seen on 28 December
1987) occurred only one day before the
sightings reported by Alan Baldridge
(Wells et al., 1990). The coastal popu-
lation of bottlenose dolphins is usually
100 m depth intervais 10 m/depth interval Point Sur found within | km (0.5 n.mi.) of shore
122°10'W 122°W 121°50'W (Hansen, 1990; Hanson and Defran,
1993) with a preference for depths of
8 10 12 14 16 818 20 22
N 20 m or less (Leatherwood and Reeves,
Nautical Miles 1982) (Fig. 7, Box A). All three of these
246 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 species have been observed during
we As ot ——————E SE
Kilometers almost every census since the 1982-83
El Nino (Table 5). These species are
Figure 6 Cetaceans in the Granite Canyon study area observed during aerial sur-
often observed in large surface-active
veys Dec.—Feb. 1980-83 (Dohl et al ). Symbols denote Pacific white-sided dol-
phins (triangle), Dall’s porpoise (square), northern right whale dolphins (circle), schools, increasing their likelihood of
killer whales (star), Risso’s dolphins (cross), and harbor porpoise (diamond). detection.
Marine Fisheries Review