Northerly Distribution of White Sharks, Carcharodon carcharias, in the Eastern Pacific and Relation to ENSO Events

Twenty-nine verified records of white sharks, Carcharodon carcharias, from British Columbia and Alaska waters (1961–2004) are presented. Record locations ranged from lat. 48°48ʹN to lat. 60°17ʹN, including the northernmost occurrence of a white shark and the first report of this species from the central Bering Sea. White sharks recorded from the study area were generally large, with 95% falling between 3.8 and 5.4 m in length. Mature white sharks of both sexes occur in British Columbia and Alaska waters, although they do not necessarily reproduce there. White sharks actively feed in the study area; their diet is similar to that reported for this species from Washington and northern California waters. Sea surface temperature (SST) concurrent with white shark records from the study area ranged from 16°C to between 6.4°C and 5.0°C, extending the lower extreme of the range of SST from which this species has been previously reported. White shark strandings are rarely reported, yet 16 (55%) of the records in this study are of beached animals; strandings generally occurred later in the year and at lower latitudes than nonstrandings. No significant correlation was found between white shark records in the study area and El Niño events and no records occurred during La Niña events. The data presented here indicate that white sharks are more abundant in the cold waters of British Columbia and Alaska than previous records suggest.

Sea Turtle Observations at Explosive Removals of Energy Structures

Observers were placed at offshore sites to monitor and protect sea turtles during explosive removals of oil and gas structures in the Gulf of Mexico off Louisiana and Texas. Data collected during more than 6,500 hours of monitoring at 106 structure removals in 1992 provided information on sea turtle distribution. Eighteen individuals were observed including 10 loggerheads, 2 leatherbacks, 1 hawksbill, and 5 unidentified sea turtles. The observation rate (individuals per monitoring hour) of sea turtles was about 30 times higher during aerial surveys than during day or night suiface surveys.

Effects of El Niño–Southern Oscillation events on catches of Bigeye Tuna (Thunnus obesus) in the eastern Indian Ocean off Java

The effects of El Niño–Southern Oscillation events on catches of Bigeye Tuna (Thunnus obesus) in the eastern Indian Ocean (EIO) off Java were evaluated through the use of remotely sensed environmental data (sea-surface-height anomaly [SSHA], sea-surface temperature [SST], and chlorophyll a concentration), and Bigeye Tuna catch data. Analyses were conducted for the period of 1997–2000, which included the 1997–98 El Niño and 1999–2000 La Niña events. The empirical orthogonal function (EOF) was applied to examine oceanographic parameters quantitatively. The relationship of those parameters to variations in catch distribution of Bigeye Tuna was explored with a generalized additive model (GAM). The mean hook rate was 0.67 during El Niño and 0.44 during La Niña, and catches were high where SSHA ranged from –21 to 5 cm, SST ranged from 24°C to 27.5°C, and chlorophyll-a concentrations ranged from 0.04 to 0.16 mg m–3. The EOF analysis confirmed that the 1997–98 El Niño affected oceanographic conditions in the EIO off Java. The GAM results indicated that SST was better than the other environmental factors (SSHA and chlorophyll-a concentration) as an oceanographic predictor of Bigeye Tuna catches in the region. According to the GAM predictions, the highest probabilities (70–80%) for Bigeye Tuna catch in 1997–2000 occurred during oceanographic conditions during the 1997–98 El Niño event.

Relationships between ENSO events and San Francisco rainfall, 1949-1991

As California entered its sixth consecutive year of drought, the onset of a positive sea surface temperature anomaly in the equatorial Pacific and other indicators of a developing ENSO event were observed. This brought the following question from the media, water officials, and the public: What effect will El Niño have on the current rainfall season in general and on the intraseasonal distribution of rain in particular? To answer the question, the historical San Francisco rainfall record was examined in relationship to previous ENSO events.

Comparative analysis of three brevetoxin-associated bottlenose dolphin (Tursiops truncatus) mortality events in the Florida Panhandle region (USA)

In the Florida Panhandle region, bottlenose dolphins (Tursiops truncatus) have been highly susceptible to large-scale unusual mortality events (UMEs) that may have been the result of exposure to blooms of the dinoflagellate Karenia brevis and its neurotoxin, brevetoxin (PbTx). Between 1999 and 2006, three bottlenose dolphin UMEs occurred in the Florida Panhandle region. The primary objective of this study was to determine if these mortality events were due to brevetoxicosis. Analysis of over 850 samples from 105 bottlenose dolphins and associated prey items were analyzed for algal toxins and have provided details on tissue distribution, pathways of trophic transfer, and spatial-temporal trends for each mortality event. In 1999/2000, 152 dolphins died following extensive K. brevis blooms and brevetoxin was detected in 52% of animals tested at concentrations up to 500 ng/g. In 2004, 105 bottlenose dolphins died in the absence of an identifiable K. brevis bloom; however, 100% of the tested animals were positive for brevetoxin at concentrations up to 29,126 ng/mL. Dolphin stomach contents frequently consisted of brevetoxin-contaminated menhaden. In addition, another potentially toxigenic algal species, Pseudo-nitzschia, was present and low levels of the neurotoxin domoic acid (DA) were detected in nearly all tested animals (89%). In 2005/2006, 90 bottlenose dolphins died that were initially coincident with high densities of K. brevis. Most (93%) of the tested animals were positive for brevetoxin at concentrations up to 2,724 ng/mL. No DA was detected in these animals despite the presence of an intense DA-producing Pseudo-nitzschia bloom. In contrast to the absence or very low levels of brevetoxins measured in live dolphins, and those stranding in the absence of a K. brevis bloom, these data, taken together with the absence of any other obvious pathology, provide strong evidence that brevetoxin was the causative agent involved in these bottlenose dolphin mortality events.

Sea surface temperature and paleo-El Niño events in Santa Barbara Basin, AD 1841-1941

Like pages of a "natural coastal diary", successive layers of anoxic varved sediment in the central Santa Barbara Basin have been used by paleoceanographers to reconstruct aspects of past coastal climate. This report focuses on the end of the "Little Ice Age" (15th to 19th century) and on the beginning of this century, a period known to encompass extreme climate excursions and weather events in the Santa Barbara Basin and other parts of Southern California. El Niño events are known to disrupt Southern California's coastal ecosystems and to cause anomalous weather conditions, but El Niño events in Southern California before 1990 have been largely undocumented.

Interdecadal shifting of the North Pacific jet stream - El Niño events [abstract]

EXTRACT (SEE PDF FOR FULL ABSTRACT): Researchers have shown a step-like increase in worldwide sea surface temperatures (SSTs) in the mid-1970s. Wintertime (December through March) polar-front jet stream positions in the North Pacific will be presented for six moderate-to-very-strong El Niño events - three before the winter of 1975-76 (1965-66, 1968-69, 1972-73) and three after (1982-83, 1986-87, 1991-92).

Offshore coho salmon populations near the Pacific Northwest and large-scale atmospheric events

EXTRACT (SEE PDF FOR FULL ABSTRACT): Catch of coho salmon off the coast of Washington and Oregon since 1925 appears to be related to large-scale events in the atmosphere, which in turn affect ocean currents and coastal upwelling intensities in the northeastern Pacific. At least two time scales of variations can be identified. The first is that of the El Nino/Southern Oscillation phenomenon giving rise to an irregular cycle of between 3 to 7 years. ... The second time scale of variation seems to have a periodicity of about 20 years, although this is based on a limited dataset. ... This paper endeavors to describe how, if real, these atmospheric/oceanic effects are integrated and might affect the salmon catch. The possibility must also be considered that the atmospheric events are symbiotically related to the oceanic events and, further, that both may be enmeshed in even longer-term variability of climate.

Chronological records of climate-related events and societal consequences [abstract]

EXTRACT (SEE PDF FOR FULL ABSTRACT): A chronology of documented regional and global warm and cold event records is collated along with documented ecosystem response records and health threat/sequellae records for the historical period. Patterns of societal response to cold periods punctuated by warm periods have been associated with considerable human health impacts, stimulated by blooms in disease vectors such as rodents and insects.